1

History of the Collision Regulations

- For several hundred years there have been rules for the purpose of preventing
collisions at sea, but no statutory rules until last century.
- In 1840, the London Trinity House drew up a set of regulations & enacted in 1846.
- A complete new set of rules drawn up by British Board of Trade & came into
operation in 1863.
- End of 1864 these rules had been adopted by over 30 maritime countries, including
US & Germany.
- Washington Conference – 1889
- Brussels Conference – 1910 reached international agreement. – remained in force
until 1954.
- 1959 SOLAS Conference proposed some minor changes to the rules, but never
ratified. (Recommendation for helm order – direct sense: ‘starboard’ means – ‘put vessels
rudder to stbd.’ which previously confused between wheel & tiller.)
- considerable increase number of ships fitted with radar and series of collisions –
Regulations for Preventing Collision at Sea were revised in 1960 and amended,
COLREG 60 by IMCO (IMO). (included conduct of vessels in RV ) – came into
force 1965.

 revised COLREG 72 developed and came into force in 1977 due t: -

1. widespread acceptance and use of radar;
2. introduction of traffic separation; and
3. increase size & speed of many ships.

 Properly called, “Convention on the International Regulations for Preventing

Collisions at Sea, 1972
as amended”.
 Amended in 1981, 1987, 1989, 1993, and 2001.
 Next amendments to Rules 3, 8, 18, 23, 31, 33, 35 and to Annex I & III. (come
into force 2003 Nov.)
 Latest amendment to Annex IV in 2007. (Ref: IMO
th
Resolution A.1004 (25) adopted on 29 November 2007)
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Foreword

The Convention on the International Regulations for Preventing Collisions at

Sea, 1972 has been accepted by many States since it was adopted on 20
October 1972 and entered into force on 15 July 1977. It was amended in 1981,
1987, 1989 and 1993 and has recently been amended by resolution A.910 (22),
which was adopted by the twenty-second session on the Assembly on 29
November 2001 and entered into force on 29 November 2003.
It has more recently been amended by resolution A.1004 (25), which
was adopted by the twenty-fifth session of the Assembly on 29 November
2007 and shall enter into force on 1 December 2009, unless by 1 June 2008
more than one third of Contracting Parties to the Convention have notified
their objection to the amendments.
This publication contains the consolidated text of the 1972 Convention
as amended in 1981, 1987, 1989, 1993, 2001. The latest 2007 amendments
which will be deemed to have entered into force as determined in the present
resolution, in accordance with the provisions of paragraph 4 of article VI of the
Convention.
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Contents
Page
Convention on the International Regulations for
Preventing Collisions at Sea, 1972, as amended……. 7

International Regulations for Preventing Collisions

at Sea,1972, as amended

Part A - General
Rule 1 – Application……………………………. 12
Rule 2 – Responsibility………………………… 15
Rule 3 - General Definitions………………….. 18
Part B - Steering and Sailing Rules
Section I - Conduct of Vessels in Any Condition of Visibility
Rule 4 – Application…………………………….. 25
Rule 5 - Look-out…………………………………. 25
Rule 6 - Safe Speed………………………………. 27
Rule 7 - Risk of Collision……………………….. 30
Rule 8 - Action to Avoid Collision……………. 34
Rule 9 - Narrow Channels……………………… 39
Rule 10 - Traffic Separation Schemes………… 42
Section II - Conduct of Vessels in Sight of One Another
Rule 11 – Application…………………………… 58
Rule 12 - Sailing Vessels……………………….. 58
Rule 13 – Overtaking…………………………… 60
Rule 14 - Head-on Situation…………………… 65
Rule 15 - Crossing Situation…………………… 67
Rule 16 - Action by Give-way Vessel……….. 69
Rule 17 - Action by Stand-on Vessel………… 70
Rule 18 - Responsibilities Between Vessels.. 75
Section III - Conduct of Vessels in Restricted Visibility
Rule 19 - Conduct of Vessels in Restricted Visibility 79
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Part C - Lights and Shapes

Rule 20 – Application…………………………. 85
Rule 21 – Definitions………………………….. 85
Rule 22 - Visibility of Lights………………….. 86
Rule 23 - Power-driven Vessels Underway.. 87
Rule 24 - Towing and Pushing………………. 88
Rule 25 - Sailing Vessels Underway and Vessels Under
Oars ……………………………………. 90
Rule 26 - Fishing Vessels……………………….. 91
Rule 27 - Vessels Not Under Command or Restricted in
Their Ability to Maneuver………….. 92
Rule 28 - Vessels Constrained by their Draft.. 93
Rule 29 - Pilot Vessels……………………………. 94
Rule 30 - Anchored Vessels and Vessels Aground 94
Rule 31 – Seaplanes………………………………. 95
Part D - Sound and Light Signals
Rule 32 – Definitions ……………………………. 95
Rule 33 - Equipment for Sound Signals ……… 95
Rule 34 - Maneuvering and Warning Signals.. 96
Rule 35 - Sound Signals in Restricted Visibility 97
Rule 36 - Signals to Attract Attention…………. 99
Rule 37 - Distress Signals……………………….. 99
Part E - Exemptions
Rule 38 – Exemptions……………………………. 100

Annexes
Annex I - Positioning and Technical Details of Lights and
Shapes …………………………………………….. 101
Annex II - Additional Signals for Fishing Vessels Fishing in
Close Proximity ………………………………… 109
Annex III - Technical Details of Sound Signal Appliances 110
Annex IV - Distress Signals ……………………………….. 113
 6
CONVENTION ON THE INTERNATIONAL REGULATIONS FOR
PREVENTING COLLISIONS AT SEA, 1972
AS AMENDED

The Parties to the present Convention,

DESIRING to maintain a high level of safety at sea,
MINDFUL of the need to revise and bring up to date the International Regulations for
Preventing Collisions at Sea annexed to the Final Act of the International Conference on
Safety of Life at Sea, 1960,
HAVING CONSIDERED those Regulations in the light of developments since they were
approved,
HAVE AGREED as follows:

Article I
General obligations
The Parties to the present Convention undertake to give effect to the Rules and other
Annexes constituting the International Regulations for Preventing Collisions at Sea,
1972, (hereinafter referred to as “the Regulations”) attached hereto.

Article II
Signature, ratification, acceptance, approval and accession
1. The present Convention shall remain open for signature until 1 June 1973 and
shall thereafter remain open for accession.

2. States Members of the United Nations, or of any of the Specialized Agencies, or

the International Atomic Energy Agency, or Parties to the Statute of the International
Court of Justice may become Parties to this Convention by:

(a) signature without reservation as to ratification, acceptance or approval;

(b) signature subject to ratification, acceptance or approval followed by

ratification, acceptance or approval; or

(c) accession.

3. Ratification, acceptance, approval or accession shall be effected by the deposit of

an instrument to that effect with the Inter-Governmental Maritime Consultative
Organization (hereinafter referred to as “the Organization”) which shall inform the
Governments of States that have signed or acceded to the present Convention of the
deposit of each instrument and of the date of its deposit.
 7

Article III
Territorial application
1. The United Nations in cases where they are the administering authority for a
territory, or any Contracting Party responsible for the international relations of a
territory, may at any time by notification in writing to the Secretary-General of the
Organization (hereinafter referred to as “the Secretary-General”), extend the application
of this Convention to such a territory.

2. The present Convention shall, upon the date of receipt of the notification or from
such other date as may be specified in the notification, extend to the territory named
therein.

3. Any notification made in accordance with paragraph 1 of this article may be

withdrawn in respect of any territory mentioned in that notification and the extension
of this Convention to that territory shall cease to apply after one year or such longer
period as may be specified at the time of the withdrawal.

4. The Secretary-General shall inform all Contracting Parties of the notification of any
extension or withdrawal of any extension communicated under this article.

Article IV
Entry into force
1. (a) The present Convention shall enter into force twelve months after the date on
which at least 15 States, the aggregate of whose merchant fleets constitutes
not less than 65 per cent by number or by tonnage of the world fleet of
vessels of 100 gross tons and over have become Parties to it, whichever is
achieved first.

(b) Notwithstanding the provisions in subparagraph (a) of this paragraph, the

present Convention shall not enter into force before 1 January 1976.

2. Entry into force for States which ratify, accept, approve or accede to this
Convention in accordance with article II after the conditions prescribed in sub-
paragraph 1(a) have been met and before the Convention enters into force, shall be on
the date of entry into force of the Convention.

3. Entry into force for States which ratify, accept, approve or accede after the date on
which this Convention enters into force, shall be on the date of deposit of an
instrument in accordance with article II.

4. After the date of entry into force of an amendment to this Convention in

accordance with paragraph 4 of article VI, any ratification, acceptance, approval or
accession shall apply to the Convention as amended.
 8
5. On the date of entry into force of this Convention, the Regulations replace and
abrogate the International Regulations for Preventing Collisions at Sea, 1960.

6. The Secretary-General shall inform the Governments of States that have signed or
acceded to this Convention of the date of its entry into force.

Article V
Revision conference
1. A conference for the purpose of revising this Convention or the Regulations or
both may be convened by the Organization.

2. The Organization shall convene a conference of Contracting Parties for the

purpose of revising this Convention or the Regulations or both at the request of not
less than one third of the Contracting Parties.

Article VI
Amendments to the Regulations
1. Any amendment to the Regulations proposed by a Contracting Party shall be
considered in the Organization at the request of that Party.
2. If adopted by a two-thirds majority of those present and voting in the Maritime
Safety Committee of the Organization, such amendment shall be communicated to all
Contracting Parties and Members of the Organization at least six months prior to its
consideration by the Assembly of the Organization. Any Contracting Party which is not
a Member of the Organization shall be entitled to participate when the amendment is
considered by the Assembly.

3. If adopted by a two-thirds majority of those present and voting in the Assembly,

the amendment shall be communicated by the Secretary-General to all Contracting
Parties for their acceptance.

4. Such an amendment shall enter into force on a date to be determined by the

Assembly at the same time of its adoption, unless, by a prior date determined by the
Assembly at the same time, more than one third of the Contracting Parties notify the
Organization of their objection to the amendment. Determination by the Assembly of
the dates referred to in this paragraph shall be by a two-thirds majority of those
present and voting.

5. On entry into force any amendment shall, for all Contracting Parties which have
not objected to the amendment, replace and supersede any previous provision to
which the amendment refers.

6. The Secretary-General shall inform all Contracting Parties and Members of the
Organization of any request and communication under this article and the date on
which any amendment enters into force.
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Article VII
Denunciation
1. The present Convention may be denounced by a Contracting Party at any time
after the expiry of five years from the date on which the Convention entered into force
for that Party.
2. Denunciation shall be effected by the deposit of an instrument with the
Organization. The Secretary-General shall inform all other Contracting Parties of the
receipt of the instrument of denunciation and of the date of its deposit.

3. A denunciation shall take effect one year, or such longer period as may be
specified in the instrument, after its deposit.

Article VIII
Deposit and registration
1. The present Convention and the Regulations shall be deposited with the
Organization, and the Secretary-General shall transmit certified true copies there-of to
all Governments of States that have signed this Convention or acceded to it.
2. When the present Convention enters into force, the text shall be transmitted by
the Secretary-General to the Secretariat of the United Nations for registration and
publication in accordance with Article 102 of the Charter of the United Nations.

Article IX
Languages
The present Convention is established, together with the Regulations, in a single copy
in the English and French languages, both texts being equally authentic. Official
translations in the Russian and Spanish languages shall be prepared and deposited with
the signed original.

IN WITNESS THEREOF the undersigned* being duly authorized by their respective

Governments for that purpose have signed the present Convention.

DONE AT LONDON this twentieth day of October one thousand nine hundred and
seventy-two.

________________
*Signature omitted.
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International Regulations for Preventing Collisions
at Sea,1972, as amended
PART A - GENERAL
Rule 1
Application
(a) These Rules shall apply to all vessels upon the high seas and in all
waters connected therewith navigable by seagoing vessels.
(b) Nothing in these Rules shall interfere with the operation of special
rules made by an appropriate authority for roadsteads, harbours,
rivers, lakes or inland waterways connected with the high seas and
navigable by seagoing vessels. Such special rules shall conform as
closely as possible to these Rules.
(c) Nothing in these Rules shall interfere with the operation of any
special rules made by the Government of any State with respect to
additional station or signal lights, shapes or whistle signals for ships
of war and vessels proceeding under convoy, or with respect to
additional station or signal lights or shapes for fishing vessels
engaged in fishing as a fleet. These additional station or signal lights,
shapes or whistle signals shall, so far as possible, be such that they
cannot be mistaken for any light, shape or signal authorized
elsewhere under these Rules.
(d) Traffic separation schemes may be adopted by the Organization for
the purpose of these Rules.
(e) Whenever the Government concerned shall have determined that a
vessel of special construction or purpose cannot comply fully with
the provisions of any of these Rules with respect to the number,
position, range or arc of visibility of lights or shapes, as well as to
the disposition and characteristics of sound-signalling appliances,
such vessel shall comply with such other provisions in regard to the
number, position, range or arc of visibility of lights or shapes, as
well as to the disposition and characteristics of sound-signalling
appliances, as her Government shall have determined to be the
closest possible compliance with these Rules in respect of that
vessel.
 11
COMMENT:

(a) These Rules apply to: -

- all vessels upon the high seas and
- all vessels in all waters connected with high seas where navigable by
seagoing vessels.

High Seas
- defined in UNCLOS (United Nations Convention on the Law of the Sea)
- All parts of the sea, not included in EEZ, Territorial sea or Internal waters,
or Archipelagic waters.

waters connected therewith navigable by seagoing vessels

- Roadsteads, harbours, rivers, lakes or inland waterways must have been

connected with high seas.

- Seagoing vessels might be able to navigate in such waters.

Quiz-1: Suppose you were in charge of a motor launch in the tidal waters of the
Yangon River and you encountered another manned boat. Should you
obey the Rules?

(b) Nothing in these Rules shall interfere with

- These Rules shall not interfere with the special rules made by the local
authority /or the Government.

Roadstead
- Open anchorage, generally protected by shoals
- but less protection than harbour.
- shoal : - a small hill of sand just below the surface of the sea:

conform as closely as possible to these Rules

- to remove any conflicts with the COLREG 72, which would be likely to
confuse mariners.
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(c) convoy
- a group of ships travelling together (in Suez canal)
- usage: squadron of warships or merchant vessels in convoy

(d) TSS adopted by IMO

- a Government prepared to implement a new scheme.
- this traffic separation scheme must be approved by the Maritime Safety
Committee (MSC), and then adopted by IMO.
- Rule 1(d) gives the IMO the authority to adopt TSS.
- TSS is routeing measure, laid down in the IMO publication – Ships’
Routeing and nautical charts concerned.
- Only after adopted by IMO, Rule 10 applies to this TSS.

(e) vessel of special construction or purpose

- originally for naval vessels (including other
vessels of special construction or purpose)
- concerning with provisions of lights, shapes or sound-signalling
appliances.
- e.g. aircraft carrier’s masthead lights – off the centre line
& reduced horizontal separation.
- e.g. sidelights – may be either side of hull / island.
nd
- e.g. warships over 50m – not fitted 2 masthead light.
- e.g. submarine’s forward masthead light – lower than
sidelights.

Summary of Rule 1
1(a) which vessels shall apply to the COLREG 72
1(b) special rules shall conform as closely as possible to COLREG72 Rules
1(c) additional station, lights, shapes, whistle signals should not be mistaken
1(d) TSS adopted by IMO.
1(e) special provisions to be closest possible compliance with these Rules
 13
Rule 2

Responsibility
(a) Nothing in these Rules shall exonerate any vessel, or the owner,
master or crew thereof, from the consequences of any neglect to
comply with these Rules or of the neglect of any precaution
which may be required by the ordinary practice of seamen, or by
the special circumstances of the case.
(b) In construing and complying with these Rules due regard shall be
had to all dangers of navigation and collision and to any special
circumstances, including the limitations of the vessels involved,
which may make a departure from these Rules necessary to
avoid immediate danger.

COMMENT:
exonerate – be free from blame / be officially not responsible for

(a) There are two types of consequences and two types of precaution: -
1. consequences of neglect to comply with these Rules
2. consequences of neglect of precaution required
a. by the ordinary practice of seamen, or
b. by the special circumstances

Precautions required by ordinary practice of seamen or special

circumstances
1. A vessel underway should keep clear of a vessel at anchor.
2. A vessel should not anchor too close to other anchored vessels.
3. In dense fog, a vessel without operational radar should not be
underway at all but should anchor if safe and practicable.
4. In tidal river, a vessel against the tide should wait until the other has
passed.
5. Shallow water effects: squat & interaction must be taken into
account.
i. Squat is more pronounced when the depth of water is less
than 1½ times the draught.
 14
ii. Bow cushion/ bank suction.
iii. Interaction between ships
6. In urgent case before adoption by IMO, to compliance a new scheme
or amendment, which a Government may implement but still not be
compulsory, considered as good seamanship to comply with Rule 10.

(b) construing – understanding the meaning of a word, a sentence, or an

action in a particular way
In construing and complying with these Rules due regard shall be had to all
dangers of navigation and collision:
- interpreted / well understood the Rules and obeyed with full regard to
the action required by these Rules,
- which might lead to unavoidable dangers of navigation and collision.
- therefore, departure may be necessary to do so.

Shallow
water

Bold Bold
alteration alteration O/T
vessel

Situation – 1 Situation – 2

Limitations of the vessels involved;

 Meeting a convoy of warships
 Meeting submarines
 Meeting a seaplane taking off or landing, etc.
 15

Quiz: Sighted the convoy ahead of about 4 to 8 miles distant. The bearing of the
innermost left-hand vessel (right ahead of your ship) is steady.
What should you do in this situation?

Special circumstances and immediate danger

- Departure may be expected to do so only if there are special
circumstances and there is immediate danger.
- Both conditions must apply.

Conclusion
• Mariners are expected to observe cautions and recommendations given in Notices
to Mariners and other official publications.
• Rule 2(a) reminds that mariners must take necessary precautions required by good
seamanship and also by special circumstances.
• Steering and Sailing Rules are expressed in the Rules of Part B – Section I, II and
III.
• According to the Rule, Action to Avoid Collision - 8(a): Any action to avoid
collision shall be taken in accordance with the Rules of this Part.
• Rule 2(b) does not give any vessel right to take action contrary to the Regulations
whenever it is considered to be advantageous to do so.
• However, master has duty to depart if necessary to avoid immediate danger would
not only be justified – but bound to do so.
• Justifiable departure must be fulfilled with the following conditions: -
1. There are present unavoidable dangers of navigation and collision if
complying with the Rules due regard;
2. There are special circumstances; and
3. There is immediate danger.

• NB: Whenever making departure from these Rules, it is crucially important to

result successful action.
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Rule 3
General definitions
For the purpose of these Rules, except where the context otherwise
requires:

(a) The word “vessel” includes every description of water craft,

including non-displacement craft, WIG craft and seaplanes, used
or capable of being used as a means of transportation on water.
(b) The term “power-driven vessel” means any vessel propelled by
machinery.
(c) The term “sailing vessel” means any vessel under sail provided
that propelling machinery, if fitted, is not being used.
(d) The term “vessel engaged in fishing” means any vessel fishing
with nets, lines, trawls or other fishing apparatus which restrict
manoeuvrability, but does not include a vessel fishing with
trolling lines or other fishing apparatus which do not restrict
manoeuvrability.
(e) The word “seaplane” includes any aircraft designed to
manoeuvre on the water.
(f) The term “vessel not under command” means a vessel which
through some exceptional circumstance is unable to manoeuvre as
required by these Rules and is therefore unable to keep out of the
way of another vessel.
(g) The term “vessel restricted in her ability to manoeuvre” means a
vessel which from the nature of her work is restricted in her
ability to manoeuvre as required by these Rules and is therefore
unable to keep out of the way of another vessel. The term “vessels
restricted in their ability to manoeuvre” shall include but not be
limited to:
(i) a vessel engaged in laying, servicing or picking up a
navigation mark, submarine cable or pipeline;
 17
(ii) a vessel engaged in dredging, surveying or underwater
operations;
(iii) a vessel engaged in replenishment or transferring persons,
provisions or cargo while underway;
(iv) a vessel engaged in the launching or recovery of aircraft;
(v) a vessel engaged in mine clearance operations;
(vi) a vessel engaged in a towing operation such as severely
restricts the towing vessel and her tow in their ability to
deviate from their course.
(h) The term “vessel constrained by her draught” means a power-
driven vessel which, because of her draught in relation to the
available depth and width of navigable water, is severely
restricted in her ability to deviate from the course she is
following.
(i) The word “underway” means that a vessel is not at anchor, or
made fast to the shore, or aground.
(j) The words “length” and “breadth” of a vessel mean her length
overall and greatest breadth.
(k) Vessels shall be deemed to be in sight of one another only when
one can be observed visually from the other.
(l) The term “restricted visibility” means any condition in which
visibility is restricted by fog, mist, falling snow, heavy
rainstorms, sandstorms or any other similar causes.
(m) The term “Wing-In-Ground (WIG) craft” means a multimodal
craft which, in its main operational mode, flies in close proximity
to the surface by utilizing surface-effect action.

Quiz: If an outboard motor dinghy being rowed along because its

motor has broken down, is it a power-driven vessel?
 18

Vessel not under command

 Adverse weather conditions seriously effecting manoeuvrability in rough
sea would be exceptional circumstances, but not justify for showing NUC
signals.
 NUC examples:
1. breakdown of engines or steering gear failure, or propeller / rudder
lost.
2. vessel anchor down but not holding, vessel riding to anchor
unshackled, and sailing vessel becalmed.

Vessel constrained by her draught

- Not only depth of water but also the width of navigable water, is used
as a factor to determine whether a vessel may be regarded as
constrained by her draught.
- Special rules in some rivers requiring signals to be exhibited by certain
size or draught do not mean to apply so as vessel constrained by her
draught.
- These are mainly vessels of very large size and tonnage
- and often called deep draught vessels, e.g. supertankers

Underway
 19

Quiz-1
- A vessel moored onto buoy is neither at anchor, nor made fast to the
shore, nor aground,
- if so, is she seemed to be underway?

WHO AM I

 However, she is secured onto mooring buoy which is riding on anchors

so that she has to display an anchor ball whenever tied on it.
 Vessel at anchor means her anchor is down and holding, but not for
riding on anchor unshackled, or dredging/dragging anchors – may be
considered as underway.
 if the anchor fouls an obstruction – at anchor

Quiz-2
- In fog, a vessel has to stop all movement through the water in order to
avoid a collision so that she is only drifting.
- if so, is she then underway?

Quiz-3
- A vessel moving ahead or astern through the water, engines stopped,
but not made fast in any way, riding on her anchor.
- In these situations, is she regarded as being underway?

Length overall Greatest breadth

Length Breadth
 20

Vessels in sight of one another

- only when one can be observed visually from the other.
- near a bend, only one can be observed visually from the other even the
other might not see visually because of obstruction – so called “in sight of
one another”.

She hasn’t
seen yet
How do you
think – are we
in sight of
BEND one another?

She starts to
see visually

 Vessels have detected one another by radar are not in visual sight: -
not in sight of one another.

Similar causes for restricted visibility may be considered as:

• Smoke from own vessel or other vessel;
• Smog or smoke from ashore;
• Dust storms.
• Obscured by an obstruction – is not to be considered as Restricted
Visibility.
• Darkness is - not a condition of restricted visibility.
 21
Wing-In-Ground (WIG) craft: - neither to be considered as seaplane nor non-
displacement craft.
(associated rules amended in Rule-18 f(i), (ii), 23(c) and 31)
• WIG craft look like aircraft, but not.
• classified as dynamically support craft.
• Engine thrust created between air foil and water surface.
• capable of increasing altitude but requires enlarge engine (loss of
economy).

WING IN GROUND CRAFT

(Volga 2, Hydrofoil)
 22

WING IN GROUND CRAFT

(Amphistar)

WING IN GROUND CRAFT

(Airfish)
 23

PART B – STEERING AND SAILING RULES

Section I – Conduct of vessels in any condition of visibility

Rule 4
Application
Rules in this section apply in any condition of visibility.

COMMENTS:
Section I covers Rule 4 to 10, for all conditions regardless of visibility,
whether the visibility is clear or restricted.

Rule 5
Look-out
Every vessel shall at all times maintain a proper look-out by sight and
hearing as well as by all available means appropriate in the prevailing
circumstances and conditions so as to make a full appraisal of the
situation and of the risk of collision.

COMMENTS:
STCW look-out laid down in Ch-VIII of STCW 78.
Principles of a Navigational Watch-keeping
• continuous proper look-out as per Rule 5;
• full appraisal of situation and risk of collision, stranding and other dangers
to navigation;
• detecting ships or aircraft in distress, survivors, debris and wrecks;
• look-out man should not undertaken other duties;
• look-out and helmsman should be separate;
• sole look-out should be in daylight only or situations safe to do so
(visibility, traffic, TSS);
• composition of navigational watch depends on weather, traffic, workload,
fitness, skill and equipment facility, etc.
 24
Duty of look-out
- in open sea, to report any lights, vessels or large floating objects;
- in low visibility, to report any fog signals;
- in crowded waters, to report lights or objects likely to risk of collision.
(small crafts – might not be observed from bridge)

'All available means' appropriate

- by radar or binoculars
- VHF information from shore or other ships
- use of radar at night even in clear visibility
- visual look-out still necessary even when using radar

full appraisal of the situation

- to pay attention to what is happening on his own vessel
- to check steering gear, autopilot or gyrocompass and other navigation
equipment functioning
- to check the vessel keeping on correct course.

What is the bad look-out?

 relying on radar plotting and no visual look-out maintained;
 no monitoring on own ship's navigation equipment;
 too relying on autopilot without vigilance;
 no proper look-out when a vessel at anchor, especially in strong tidal
turning or other vessels passing by.
 25
Rule 6
Safe speed
Every vessel shall at all times proceed at a safe speed so that she can
take proper and effective action to avoid collision and be stopped within
a distance appropriate to the prevailing circumstances and conditions.
In determining a safe speed the following factors shall be among those
taken into account:
(a) By all vessels:
(i) the state of visibility;
(ii) the traffic density including concentrations of fishing vessels
or any other vessels;
(iii) the manoeuvrability of the vessel with special reference to
stopping distance and turning ability in the prevailing
conditions;
(iv) at night the presence of background light such as from shore
lights or from back scatter of her own lights;
(v) the state of wind, sea and current, and the proximity of
navigational hazards;
(vi) the draught in relation to the available depth of water.

(b) Additionally, by vessels with operational radar:

(i) the characteristics, efficiency and limitations of the radar
equipment;
(ii) any constraints imposed by the radar range scale in use;
(iii) the effect on radar detection of the sea state, weather and
other sources of interference;
(iv) the possibility that small vessels, ice and other floating
objects may not be detected by radar at an adequate range;
(v) the number, location and movement of vessels detected by
radar;
(vi) the more exact assessment of the visibility that may be
possible when radar is used to determine the range of vessels
or other objects in the vicinity.
 26

COMMENT:
safe speed
- the speed that she can take proper and effective action to avoid collision
and be stopped within a distance appropriate to the prevailing
circumstances and conditions.
at all time
- engine movement order is always at OOW's disposal and should not
hesitate to use engine in case of necessity.

proper and effective action

 neither too high nor too low for proper and effective action in some
circumstances;
 by considering loss of steerage way due to reduce speed or take all
way off.

with a distance appropriate to

 previously interpreted as within half the range of visibility;
(misconception)
 not justifiable for about dense fog not possible to see beyond
forecastle head;
 specific value depends upon particular case.
 factors listed in the rule – by all vessels/ by vessels with operational
radar.

Crash stop (stop from full speed – might be taking all way off)
– takes a ship distance of 5L to 15L (L = ship's length)

'Operational radar' means – radar in use

characteristics, efficiency and limitations

 fails to detect small targets;
 normal or ARPA radars;
 shadow or blind sectors.
 27

range scale
 longer range may reduce detection of small objects;
 shorter range not possible for early detection;
 should not change from short range if dangerous target at close
range.
 if two radars available – use in different range scale.

interference
- small craft not detected if interference is present;
- rain clutter less effect on 10 cm radar then 3 cm radar
- 10cm radar more suitable to use in rain;

small craft and ice

- small craft of fiberglass or wooden construction or small icebergs may
not be detected by radar so as to be dangerous to navigation;
- SOLAS requires <150gt vessels – to fit radar reflector at 4 m above water
level.

number, location and movement of vessels detected

- more difficult to determine among the greater number of targets;
- low speed vessels likely to be frequently overtaken by other ships, but
high speed vessels also not necessarily justified.

assessment of visibility
- possible to determine the range of visibility by observing radar range to
sighted vessels or objects in vicinity.
 28

Rule 7
Risk of collision
(a) Every vessel shall use all available means appropriate to the
prevailing circumstances and conditions to determine if risk of
collision exists. If there is any doubt such risk shall be deemed to
exist.
(b) Proper use shall be made of radar equipment if fitted and
operational, including long-range scanning to obtain early
warning of risk of collision and radar plotting or equivalent
systematic observation of detected objects.
(c) Assumptions shall not be made on the basis of scanty
information, especially scanty radar information.
(d) In determining if risk of collision exists the following
considerations shall be among those taken into account:
(i) such risk shall be deemed to exist if the compass bearing of
an approaching vessel does not appreciably change;
(ii) such risk may sometimes exist even when an appreciable
bearing change is evident, particularly when approaching a
very large vessel or a tow or when approaching a vessel at
close range.

COMMENT:
all available means
1. visual compass bearings;
2. radar plotting;
3. clarification by VHF information for their intentions;
4. in TSS, traffic information;
5. sometime wasted attempt to make radio contact instead of ROC
assessment and action;
6. sometime misunderstanding may lead to endanger.
7. Now AIS useful for collision avoidance but not all vessels might have
not fitted yet.
 29
 to bear in mind that AIS does neither replace any tracking system
nor cease responsibility of OOW.
 to take advantage to obtain from AIS that can provide even when
targets lost in radar due to clutter.

Proper use of radar equipment

- stabilized mode enabling to read compass directly without burring
targets due to course alteration;
- true motion suitable for use in shorter range scales, congested water
rather than open sea;
o true motion – faster and easier to determine target's behaviour;
o relative motion – easier to determine ROC exists or not.
- if two radars on, relative and true motion to be set;

equivalent systematic observation

 to observe at regular intervals;
 true plot – convinces alteration of course or speed
 relative – enables CPA / TCPA
 such as ARPA
 if limited number, to discard unnecessary targets' plotting and
concentrate on important targets.

scanty information
inaccurate plotting;
plotting with error in bearing;
random observation rather than regular intervals;
ignorance of target's speed or course alteration;
taking bearing when rolling or pitching;
relying only on radar rather than visual bearing.

Compass bearing of an approaching vessel does not appreciably change

 whenever compass bearing does not appreciably change may not

mean to be risk of collision existing.
Case-1: Bearing of a same-way vessel with same speed on
starboard bow at distance of 3nm will not change – it
doesn't mean that ROC exists!!!
 30
Case-2: Steady bearing of a vessel with higher speed on starboard
bow but distance increased from 3nm to 5nm – it does not
mean that ROC exists!

Brg does not change,

Distance unchanged

Brg does not change,

Distance increases

Case-
1 Case-2
 If ROC exists: -
1. compass bearing does not appreciably change, and
2. distance must be decreasing.
 bearing between vessels (i.e. true bearing) – not relative bearing.

Quiz: in your opinion, how small can you allow a change of bearing not
appreciably changed?

Approaching a vessel at close range

 when a bearing taken forward of a towing vessel is closing and aft end
of vessel being towed is opening – surely will cross the towline, of
course.
31
 32

Rule 8
Action to avoid collision
(a) Any action to avoid collision shall be taken in accordance with the
Rules of this Part and shall, if the circumstances of the case admit, be
positive, made in ample time and with due regard to the observance of
good seamanship.
(b) Any alteration of course and/or speed to avoid collision shall, if the
circumstances of the case admit, be large enough to be readily
apparent to another vessel observing visually or by radar; a succession
of small alterations of course and/or speed should be avoided.
(c) If there is sufficient sea-room, alteration of course alone may be the
most effective action to avoid a close-quarters situation provided that it
is made in good time, is substantial and does not result in another close-
quarters situation.
(d) Action taken to avoid collision with another vessel shall be such as to
result in passing at a safe distance. The effectiveness of the action shall
be carefully checked until the other vessel is finally past and clear.
(e) If necessary to avoid collision or allow more time to assess the
situation, a vessel shall slacken her speed or take all way off by
stopping or reversing her means of propulsion.
(f) (i) A vessel which, by any of these Rules, is required not to impede
the passage or safe passage of another vessel shall, when required
by the circumstances of the case, take early action to allow
sufficient sea-room for the safe passage of the other vessel.
(ii) A vessel required not to impede the passage or safe passage of
another vessel is not relieved of this obligation if approaching the
other vessel so as to involve risk of collision and shall, when
taking action, have full regard to the action which may be required
by the Rules of this part.
(iii) A vessel the passage of which is not to be impeded remains fully
obliged to comply with the Rules of this part when the two vessels
are approaching one another so as to involve risk of collision.
 33
COMMENT:
(a) Action shall be taken in accordance with the Rules of Part B
nd
 IMO 22 Assembly established direct link between Rule 8 with Part B
Steering and Sailing Rules.
 reason is for conflicting action in near head-on or in fine crossing
situations – avoiding action to port to achieve safe passing distance in
accordance with Rule 8(d) rather than alter course to starboard in
accordance with Section II & III of Part B.
Positive action in ample time
- action must be correct and successful;
- carefully assessed before taken action, not based on scanty information;
o e.g. If the give-way vessel takes action in good time, the
stand-on vessel should maintain her course and speed, but
not justified for taking action in accordance with Rule 17(a)(ii).
o Rule 8(a) does not give a vessel required to keep her course
and speed the right to take action at early stage.
o Stand-on vessel should give whistle signal 34(d) before such
action as Rule 17(a)(ii).
NB POSITIVE, EARLY, and SUBSTANTIAL Action in every case.
(b) large enough to be readily apparent
- In R/V, substantial action must be readily apparent to another vessel
observing by radar.
(e.g. A/C at least 30º, prefer 60º to 90º)
- in sight of one another, different sidelight would be visible.

(c) alteration of course alone

- alteration of course is most effective action in head-on or fine bow;
- sometimes in overtaking situation.

(d) passing at a safe distance

- it depends on the situation and regards as safe speed;
- the fact to be taken into account – other vessel may encounter engine
or steering failure at any time.
 34

effectiveness of the action to be checked

- to avoid renewed ROC more dangerous if both vessels turn towards
each other;
- to avoid misunderstanding between vessels;

(e) reduction of speed

- probable causes to reduce speed are two intentions: -
(i) if necessary to avoid collision, or
(ii) if necessary to assess the situation
- possible delay factors must be known before making astern: -
(i) loss of steerage way;
(ii) transverse effect may be off course of 90º or more;
(iii) strong wing effect due to pivot point shifted;
(iv) shallow water effect may become more pronounced;
- momentum to be considered;
- crash stop from full speed – 5 to 15 ship lengths: - vary with speed,
displacement and types of engine, etc.;

(f) impede – what does it mean?

 impede – likely to develop ROC
 not to impede – to avoid the development of ROC;
 comply for Rule 9(b),(c),(d), 10(i),(j) and 18(d),(e),(f)
 35
For example,

VCBD

O/S
PDV

 Rule 18(d)(i) mention that PDV has to avoid

impeding the safe passage of a VCBD.
 Own ship – vsl not to impede
 Other – vsl not to be impeded
 O/S follows Rule 8(f)(i) and take early action to
allow sufficient sea room for VCBD.

 If not possible, e.g. a day signal or light signal may not be recognized at
sufficient distance for take early action.
 Rule 8(f)(ii) states clearly that Vsl not to impede is not relieved of the
obligation to allow sufficient sea room, if approaching the other vessel so
as to involve risk of collision even though the other vsl may become the
give-way vsl.
(O/S may be assumed as stand-on vessel & apply Rule 17(a)(ii))

 when taking action, have full regard to the action which may be required by
the Rules of this part – means
"Vessel not to impede should have full regard to the action which may be
taken by the other vessel" as required by the Rules of Part-B Steering and
Sailing Rules.
 36

Rule 9
Narrow channels
(a) A vessel proceeding along the course of a narrow channel or
fairway shall keep as near to the outer limit of the channel or
fairway which lies on her starboard side as is safe and practicable.
(b) A vessel of less than 20 metres in length or a sailing vessel shall
not impede the passage of a vessel which can safely navigate only
within a narrow channel or fairway.
(c) A vessel engaged in fishing shall not impede the passage of any
other vessel navigating within a narrow channel or fairway.
(d) A vessel shall not cross a narrow channel or fairway if such
crossing impedes the passage of a vessel which can safely
navigate only within such channel or fairway. The latter vessel
may use the sound signal prescribed in Rule 34(d) if in doubt as
to the intention of the crossing vessel.
(e) (i) In a narrow channel or fairway when overtaking can take
place only if the vessel to be overtaken has to take action to
permit safe passing, the vessel intending to overtake shall
indicate her intention by sounding the appropriate signal
prescribed in Rule 34(c)(i). The vessel to be overtaken shall,
if in agreement, sound the appropriate signal prescribed in
Rule 34(c)(ii) and take steps to permit safe passing. If in
doubt she may sound the signals prescribed in Rule 34(d).
(ii) This Rule does not relieve the overtaking vessel of her
obligation under Rule 13.
(f) A vessel nearing a bend or an area of a narrow channel or fairway
where other vessels may be obscured by an intervening
obstruction shall navigate with particular alertness and caution
and shall sound the appropriate signal prescribed in Rule 34(e).
(g) Any vessel shall, if the circumstances of the case admit, avoid
anchoring in a narrow channel.
 37

Narrow Channel
- not easily defined, neither necessary to be definite length nor terminate
last buoys or marking.
- channel between two piers & 100m outwards beyond a harbour
entrance.
- sometimes approx: up to 2 miles wide
- not to apply as recommended route between two buoys, outside could
be safe.
- not to apply traffic lanes as TSS although it may be relatively narrow.

Fairway
- open navigable passage of water.
- channel dredged and maintained by port authority.
- marked by pecked lines on chart

Keep near to the outer limit

- not passing dangerously too close to the shoals;
- not to make frequent alterations of course in order to keep near outer
limit of every part of the channel.
- just near outer limit as safe and practicable.

Impeding vessels
 9(b),(c): Vessels of less than 20m in length, sailing vessels and vessels
engaged in fishing must avoid impeding the safe passage of another
vessel, without waiting to determine if ROC exists.
When the two vessels are approaching one another so as to involve risk
of collision, a PDV remains fully obliged to comply with the Rules of Part-B,
to keep out of the way of: -
(i) pdv<20m being overtaken;
(ii) crossing from her stbd side; or
(iii) sailing vessel,
 38

 9(d) Crossing narrow channel

- Vessels must not cross NC or Fairway if impedes the passage of any
other vessel within the channel.
- does not mean that 'Crossing Rule not apply in NC'
- If approaching one another so as to involve ROC, vessels must comply
with the Rules of Part-B.
- In crossing situation in NC, should reduce speed as Rule 8(e).

(e) Overtaking in a narrow channel

- overtaking only after understood by mutual agreement.
- good seamanship of vessel to be overtaken – to move away for safe
passing & to reduce speed to decrease running time parallels each
other.
- if possible, whistle signal should be supplemented by VHF radio to
clarify the situation.

(f) Bends in channel

- On approaching a bend, a vessel must sound one prolong blast as
prescribed in Rule 34(e).
- If heard such signal from another vessel, she answers by further signal –
one prolong blast.
- Good seamanship – vessel stemming the tide to wait until the other
vessel has passed and clear.

(g) Anchoring in NC
- is likely to impede the safe passage of other vessels

Quiz: You are OOW of a VRAM approaching the bend in the channel, what signal
would you make?
 39

Rule 10
Traffic separation schemes
(a) This Rule applies to traffic separation schemes adopted by the
Organization and does not relieve any vessel of her obligation under
any other rule.
(b) A vessel using a traffic separation scheme shall:
(i) proceed in the appropriate traffic lane in the general direction of
traffic flow for that lane;
(ii) so far as practicable keep clear of a traffic separation line or
separation zone;
(iii) normally join or leave a traffic lane at the termination of the lane,
but when joining or leaving from either side shall do so at as small
an angle to the general direction of traffic flow as practicable.
(c) A vessel shall, so far as practicable, avoid crossing traffic lanes but if
obliged to do so shall cross on a heading as nearly as practicable at right
angles to the general direction of traffic flow.
(d) (i) A vessel shall not use an inshore traffic zone when she
can safely use the appropriate traffic lane within the adjacent
traffic separation scheme. However, vessels of less than 20 metres
in length, sailing vessels and vessels engaged in fishing may use
the inshore traffic zone.
(ii) Notwithstanding subparagraph (d)(i), a vessel may use
an inshore traffic zone when en route to or from a port, offshore
installation or structure, pilot station or any other place situated
within the inshore traffic zone, or to avoid immediate danger.
(e) A vessel other than a crossing vessel or a vessel joining or leaving a
lane shall not normally enter a separation zone or cross a separation line
except:
(i) in cases of emergency to avoid immediate danger;
(ii) to engage in fishing within a separation zone.
(f) A vessel navigating in areas near the terminations of traffic separation
schemes shall do so with particular caution.
(g) A vessel shall so far as practicable avoid anchoring in a traffic
separation scheme or in areas near its terminations.
 40
(h) A vessel not using a traffic separation scheme shall avoid it by as wide
a margin as is practicable.
(i) A vessel engaged in fishing shall not impede the passage of any vessel
following a traffic lane.
(j) A vessel of less than 20 metres in length or a sailing vessel shall not
impede the safe passage of a power-driven vessel following a traffic
lane.
(k) A vessel restricted in her ability to manoeuvre when engaged in an
operation for the maintenance of safety of navigation in a traffic
separation scheme is exempted from complying with this Rule to the
extent necessary to carry out the operation.
(l) A vessel restricted in her ability to manoeuvre when engaged in an
operation for the laying, servicing or picking up of a submarine cable,
within a traffic separation scheme, is exempted from complying with
this Rule to the extent necessary to carry out the operation.

IMO General Provisions on Ship's Routeing

1. Unless stated otherwise, routeing systems are recommended for use by all ships
and may be made mandatory for all ships, certain categories of ships or ships
carrying certain cargoes.
2. For use by day and by night in all weathers, in ice-free waters or under light ice
conditions where no extraordinary manoeuvres or assistance by ice-breaker(s) are
required.
3. Bearing in mind - under-keel clearance, charted depth, possible seabed changes
from last survey, and effects of meteorological and tidal conditions on water
depths.
4. A ship navigating in or near a TSS adopted by IMO shall comply Rule 10 to
minimize the development of risk of collision with another ship. The other
COLREG72 rules (Part-B Section II & III) apply if ROC is deemed to exist.***
5. At junction points, to navigate with great caution and through-going ship has no
special privilege or right of way. (Fig. 7&8)
6. Deep-water route – primarily for use by deep-draught ships. Other ships should
avoid using DW routes if practicable.
 41

7. Precautionary areas should be avoided, if practicable, by passing ships not

making use of the associated TSS or deep-water routes, or entering or leaving
adjacent ports.
8. To keep starboard side in two-way routes.
9. Need not to strictly follow along the general direction- .
10. YG – You appear not to be complying with TSS. (INTERCO)

TRAFFIC SEPARATION SCHEME

Inshore Traffic Zone

Separation Line

DW

Traffic Separation Zone

DW route

Traffic Lane

General Direction
of Traffic Flow
 42

Quiz: As shown in sketch, vessel A is proceeding to her destination for anchorage.

Is she following a proper course?

DEFINITIONS
The following terms are used in connection with matters related to ships' routeing:

1. Routeing system
Any system of one or more routes or routeing measures aimed at reducing the
risk of casualties; it includes traffic separation schemes, two-way routes,
recommended tracks, areas to be avoided, no anchoring areas, inshore traffic
zones, roundabouts, precautionary areas and deep-water routes.

2. Mandatory routeing system

A routeing system adopted by the Organization, in accordance with the
requirements of regulation V/10 of the SOLAS 74, for mandatory use by all ships,
certain categories of ships or ships carrying certain cargoes.

3. Traffic separation scheme*

A routeing measure aimed at the separation of opposing streams of traffic by
appropriate means and by the establishment of traffic lanes.
 43

4. Separation zone or line*

A zone or line separating the traffic lanes in which ships are proceeding in
opposite or nearly opposite directions; or separating a traffic lane from the
adjacent sea area; or separating traffic lanes designated for particular classes of
ship proceeding in the same direction.

5. Traffic lane*
An area within defined limits in which oneway traffic is established. Natural
obstacles, including those forming separation zones, may constitute a boundary.

6. Roundabout
A routeing measure comprising a separation point or circular separation zone and
a circular traffic lane within defined limits. Traffic within the roundabout is
separated by moving in a counterclockwise direction around the separation point
or zone.

7. Inshore traffic zone*

A routeing measure comprising a designated area between the landward
boundary of a traffic separation scheme and the adjacent coast, to be used in
accordance with the provisions of rule 10(d), as amended, of the International
Regulations for Preventing Collisions at Sea, 1972 (Collision Regulations).

8. Two-way route
A route within defined limits inside which two-way traffic is established, aimed at
providing safe passage of ships through waters where navigation is difficult or
dangerous.
 44
9. Recommended route
A route of undefined width, for the convenience of ships in transit, which is often
marked by centreline buoys.

10. Recommended track

A route which has been specially examined to ensure so far as possible that it is
free of dangers and along which ships are advised to navigate.

11. Deep-water route

A route within defined limits which has been accurately surveyed for clearance of
sea bottom and submerged obstacles as indicated on the chart.

12. Precautionary area

A routeing measure comprising an area within defined limits where ships must
navigate with particular caution and within which the direction of traffic flow may
be recommended.

13. Area to be avoided

A routeing measure comprising an area within defined limits in which either
navigation is particularly hazardous or it is exceptionally important to avoid
casualties and which should be avoided by all ships, or certain classes of ship.

14. No anchoring area

A routeing measure comprising an area within defined limits where anchoring is
hazardous or could result in unacceptable damage to the marine environment.
Anchoring in a no anchoring area should be avoided by all ships or certain classes
of ships, except in case of immediate danger to the ship or the persons on board.
 45
15. Established direction of traffic flow
A traffic flow pattern indicating the directional movement of traffic as established
within a traffic separation scheme.

16. Recommended direction of traffic flow

A traffic flow pattern indicating a recommended directional movement of traffic
where it is impractical or unnecessary to adopt an established direction of traffic
flow.
46
47
48
 49

Does not relieve obligation under any other Rule

 A PDV following a traffic lane is not relieved of her obligation to keep out of the
way of another PDV seen on her own starboard side in crossing situation if ROC
exists.
 Details of TSS adopted by IMO are depicted on nautical charts and contained in
Ship's Routeing.
 Some governments have adopted TSS within their territorial waters, which are not
officially adopted by IMO.
 Such voluntary TSS should be observed in NP's such as Sailing Directions and their
relevant documents.
 A government may recommend the use of TSS in internal waters, without IMO
adoption. Rule 10 will not apply to such scheme, but to be considered as good
seamanship to comply with recommendations in acc: with Rule 2(a). (American
Aquarius* vs Atlantic Hope collision in 1973)

Crossing traffic lanes

- cross on a heading – not the course made good.

- For a sailing vessel, auxiliary engine if fitted should be used, otherwise, assumed as
guilty of contravening Rule 10(c). (e.g. a training sailing vessel De Eendracht in 1986)

Inshore traffic zones

- en route ~ on the way; while travelling from/to a particular place.

Vessels permitted to enter inshore zones: -

1. vessel proceeding en route to or from a port, offshore …
2. vessel of less then 20m in length
3. sailing vessels
4. vessels engaged in fishing
5. vessels to avoid immediate danger in case of emergency

Vessels permitted to enter separation zones: -

1. vessel crossing traffic lane

2. vessels joining or leaving a lane

3. vessels engaged in fishing

4. vessels to avoid immediate danger in case of emergency

 50
Near the termination of TSS

- primary objective of TSS: - to reduce meeting or fine crossing situations.

- to navigate with particular caution in areas near the terminations of TSS;
- because fine crossing situations near the terminations due to converging and
diverging traffic.

Avoid anchoring
- TSS aims to move vessels along the lane in same direction
- obstruction to the traffic flow
- more dangerous in restricted visibility
- serious obstruction when lying broad angle due to wind or stream.

If not using TSS

- to avoid TSS by as wide a margin as is practicable.

- if TSS made mandatory, 10(h) will not apply.

Impeding by fishing vessels and vessels <20m

For Example,

S/Vsl

O/S
PDV
 51
 so called 'vessels not to impede'

 they have to comply Rule 8(f)(i) and take early action to

allow sufficient sea room for PDV
 Rule 8(f)(ii) - If not and ROC involved, she is not relieved for the above obligation
and has full regard to the action, which may be taken by PDV.

 8(f)(iii) - For PDV, not to be impeded remains fully obliged to comply with the Part-
B Steering & Sailing Rules when ROC exists.
i.e. PDV is not relieved of the obligation to keep out of the way, if there is ROC with
a sailing vessel, required by Rule 18(a).

YG Signal received
- means 'You appear not to be complying with the TSS';
- whatever means should take immediate steps to check own course and position
and take action as appropriate.

Cable work and safety operation

- such vessel may be not possible to comply with the Rule 10 to cross at right
angles or proceed along the general direction of traffic flow;
- to the extent necessary to carry out the operation;
- VRAM should exhibits signals as required by Rule 27(b);
- promulgated beforehand by NTMs and subsequent radio warnings during
operation.

A
B
C
D

Hong Kong TSS

Quiz: Which of the four routes shown would most nearly accord with the intentions of the
Rules?(A or B or C or D?)
 52

Section II – Conduct of vessels in sight of one another

Rule 11

Application
Rules in this section apply to vessels in sight of one another.

Rule 12

Sailing vessels
(a) When two sailing vessels are approaching one another, so as to
involve risk of collision, one of them shall keep out of the way of
the other as follows:
(i) when each has the wind on a different side, the vessel which
has the wind on the port side shall keep out of the way of the
other;
(ii) when both have the wind on the same side, the vessel which
is to windward shall keep out of the way of the vessel which
is to leeward;
(iii) if a vessel with the wind on the port side sees a vessel to
windward and cannot determine with certainty whether the
other vessel has the wind on the port or on the starboard side,
she shall keep out of the way of the other.
(b) For the purpose of this Rule the windward side shall be deemed to
be the side opposite to that on which the mainsail is carried or, in
the case of a square-rigged vessel, the side opposite to that on
which the largest fore-and-aft sail is carried.
 53
A keeps clear of B, C, D B keeps clear of C
B stands on for A, D

A B

D C
D keeps clear of B, C C stands on for A, B, D
D stands on for A

C
Overtaking Situations?
 54

Rule 13

Overtaking
(a) Notwithstanding anything contained in the Rules of part B, sections I
and II, any vessel overtaking any other shall keep out of the way of the
vessel being overtaken.
(b) A vessel shall be deemed to be overtaking when coming up with
another vessel from a direction more than 22.5 degrees abaft her beam,
that is, in such a position with reference to the vessel she is overtaking,
that at night she would be able to see only the stern light of that vessel
but neither of her sidelights.
(c) When a vessel is in any doubt as to whether she is overtaking another,
she shall assume that this is the case and act accordingly.
(d) Any subsequent alteration of the bearing between the two vessels shall
not make the overtaking vessel a crossing vessel within the meaning of
these Rules or relieve her of the duty of keeping clear of the overtaken
vessel until she is finally past and clear.

COMMENT:
 Notwithstanding anything contained in the Rules of part B, sections I and II,
 Clearly stated that a vessel proceeding along the narrow channel or traffic
lane shall keep out of the way of any vessel she is overtaking.
 A sailing vessel overtaking must keep out of the way of another sailing
vessel, irrespective of wind direction.
Subsequent alteration of bearing

(1). A vessel coming up to another vessel from direction more than 22.5º abaft
her starboard beam;
(2). overtakes and reaches abeam;
(3). draws ahead and then subsequently turns to port to a crossing course to
ahead of the vessel being overtaken.
 55

A A A

d=1nm B
B B

3
1 2

NB: If distance between A & B is about 5nm, vessel A may become a give-
way vessel,
however, vessel B, in doubtful case, should assume to keep out of the
way.
Action by overtaking vessel if necessary to cross
- Overtaking vessel is not required to avoid crossing ahead of the other
vessel
- nevertheless, altering course, or reducing speed, in order to pass astern of
the vessel being overtaken – safest action.
Overtaking or Crossing?

A A

B
4

1 2 3
(1) PDV "A" approaches another PDV"B" from a direction approx: 22.5º abaft her
beam – may be in doubt;
(No doubt for night time – cause of sidelights seen)

(2) Vessel "B" preferable turn to parallel course;

(3) "B" obliged to keep out of the way of "A";

(4) "B" will subsequently pass ahead of "A".

 56
INTERACTION

 roughly parallel courses: - attraction and repulsion set up;

 greatest effect in shallow water, moving with high speed/same direction;
 passing on opposite courses – interaction little effect;
 more affected when a large vessel overtaking a small one.
 to avoid passing too close in open water;
 to avoid passing at high speed in narrow channel.

A A

Fig. 1 Fig. 2
B B

A A

Fig. 3
Fig. 4
B B

Fig.1:
- increase water pressure near A's bow and B's stern / decrease pressure amidships.
- repulsion experienced.
- B swings her bow across the path of "A".
Fig.2:
- Later turning moment is reverse, vessel B swings outward.
- attraction experienced.
Fig.3:
- repulsive force between them, B's bow swings inwards.
Fig.4:
- Finally, after A passed the stern of B, turning moment on B is outwards again.
 57

Overtaking in narrow channels and traffic lanes

 Rule 13 overrides other Rules in Section I & II,
 but does not give small vessels, s/v & f/v the right to impede the passage
of any vessel overtaking in NC & traffic lane.
 If ROC exists, prime responsibility is by overtaking vessel to keep out of the
way of the vessel being overtaken.
 In NC, mutual agreement is required between two vessels.
 CAUTION!
(i) Collision due to close proximity of vessels;
(ii) Interaction between vessels – one sheers towards the other or bank
and leading to collision / grounding.
(iii) Interaction between vessels and bank – sheers towards or away from
bank and leading to collision or grounding.
 58

Rule 14
What is h On situation
Head-on situation No body give way /no body stand on

(a) When two power-driven vessels are meeting on reciprocal or nearly

reciprocal courses so as to involve risk of collision each shall alter her
course to starboard so that each shall pass on the port side of the other.
(b) Such a situation shall be deemed to exist when a vessel sees the other
ahead or nearly ahead and by night she could see the masthead lights of
the other in a line or nearly in a line and/or both sidelights and by day
she observes the corresponding aspect of the other vessel.
(c) When a vessel is in any doubt as to whether such a situation exists she
shall assume that it does exist and act accordingly.

COMMENT:
 Applies to power-driven vessels only.
 Reciprocal courses: - masts or masthead lights nearly in line
e.g.

View as or or
 59
 However, Rule 14 does not apply to the condition in which only one
sidelight can be seen, but the other is obscured.
 Annex I-9. Horizontal sector: (a)(i) – sidelights' practical cut-off between 1º
and 3º.
 One of the sidelights may be seen up to 3º on the opposite bow.
 i.e. Specifically, the probable variation of the estimated courses of both
vessels on head-on situation may be within 6º ± 180º.
 Nevertheless, if in doubt they should assume it does exist.

Ship's heading – not Course made good

Co. made good

B
WIND
Course to steer
 Rule makes clear that it is the direction of the ship's head, not CMG – to
determine whether head-on or crossing.
 Due to strong wind or tide, one vessel sees the other end on starboard bow
but bearing remains constant, as shown in Fig.
 Both may attempt to alter course to port – it would not be in accordance with
the Rules.
 Vessel "A" which has the other on her own starboard side is required to
keep out of the way by Rule 15 and should alter course to starboard to
avoid crossing ahead of "B".
 Para(c) makes clear – if in doubt, to assume it does exist.
 Whether PDVs are meeting on reciprocal courses or crossing at fine angle,
neither should alter course to port.

NB: Many collisions caused by alteration to port to increase passing distance,

meanwhile, the other vessel turned to starboard.
 60
Rule 15

Crossing situation
When two power-driven vessels are crossing so as to involve
risk of collision, the vessel which has the other on her own starboard
side shall keep out of the way and shall, if the circumstances of the case
admit, avoid crossing ahead of the other vessel.

COMMENT:
 Although vessels in opposite direction in a narrow channel or bend may
come into a crossing situation, Rules 15 and 17 do not apply.
 They must comply with Rule 9(a) and keep as near to the outer limit, which
lies on her starboard side, as is safe and practicable.
 Rule 15 does not apply to two PDVs crossing so as to involve ROC if one
PDV is NUC, VRAM or engaged in fishing.
 Rule 18 applies in such circumstances and a PDV needs not to avoid
crossing ahead.
 If in doubt, whether the other vessel is actually hampered or not due to
difficulty of recognizing day signals or lights, A/C to starboard may be the
best action.
 No special privilege to towing vessel – considered as a PDV.
 A VCD is expected to keep out of the way of a PDV in crossing situation on
her starboard side – but PDV remains fully obliged to allow sufficient sea
room for VCD and should take full account of the limited manoeuvrability.
 61

Avoid crossing ahead

 At long ranges, it does not apply before ROC exists or the bearing is
appreciably changing. (see e.g.1)
 If ROC exists, the give-way vessel must avoid crossing ahead.
e.g. – 1

Brg changed,
from 045º to 075º
distance ~ 10 nm Brg. 075º
A/C to
port

 In a crossing situation, a PDV is required to avoid crossing ahead of a PDV

on her own starboard side, if there is ROC exists, but not directed to cross
astern.
 A/C to starboard – best method but reduce speed or substantial alteration
to port would be preferable in order to avoid collision with a vessel
approaching from near the starboard abeam.

e.g. – 2 Vessel approaching from near

the starboard abeam

Brg. 080º
Brg. 080º

A/C to port

 Vessel lying stopped with her engines ready for manoeuvre is not entitled
to show for any privileged lights or light signals – must comply Rules 14, 15
and 18.
 62
Rule 16

Action by give-way vessel

Every vessel which is directed to keep out of the way of another vessel
shall, so far as possible, take early and substantial action to keep well
clear.

COMMENT:

 Give-way vessel – every vessel, which is directed to keep out of the way of
another vessel, as required by Rules 12, 13, 15 and 18.
 The 'give-way vessel' is required to take early and substantial action to
keep well clear.
 By complying Rule 8,
(i) any alteration of course or speed to avoid collision should be made in
ample time and be large enough to be readily apparent to another
vessel;
(ii) action shall be such as to result in passing at a safe distance;
(iii) the effectiveness of the avoiding action must be checked until finally
past and clear and,
(iv) if necessary, slacken her speed of take all way off.

NB: The obligations of a give-way vessel are specified in Rules 8 and 16.
 63

Rule 17

Action by stand-on vessel

(a) (i) Where one of two vessels is to keep out of the way the
other shall keep her course and speed.
(ii) The latter vessel may however take action to avoid
collision by her manoeuvre alone, as soon as it becomes
apparent to her that the vessel required to keep out of the way
is not taking appropriate action in compliance with these
Rules.
(b) When, from any cause, the vessel required to keep her course and
speed finds herself so close that collision cannot be avoided by
the action of the give-way vessel alone, she shall take such action
as will best aid to avoid collision.
(c) A power-driven vessel which takes action in a crossing situation
in accordance with subparagraph (a)(ii) of this Rule to avoid
collision with another power-driven vessel shall, if the
circumstances of the case admit, not alter course to port for a
vessel on her own port side.
(d) This Rule does not relieve the give-way vessel of her obligation
to keep out of the way.

COMMENT:
One vessel is to keep out of the way ~ give-way vessel.
The other to keep her course and speed ~ stand-on vessel
 Give-way Vessel – every vessel, which is directed to keep out of the way of
another vessel, as required by Rules 12, 13, 15 and 18.
 Stand-on Vessel – the other vessel, which is required to keep her course
and speed.
 Rule 17 lays down provisions for the other vessel, referred to as the 'stand-
on vessel'.
 64
 Rule 17 does not apply: - not in sight of one another
- no ROC.
 e.g. a PDV detects another vessel by radar approaching from port bow or
more than 22.5º abaft the beam that bearing is not changing – not required
to keep her course and speed. (if the vessel cannot be sighted visually)

(a)(i) keep course and speed

- Not necessarily have to remain the same course and same RPM

(a)(ii) may take action

- A stand-on vessel is not specifically required to take action to avoid
collision as soon as apparently the give-way vessel is not taking
appropriate action.
- She is permitted to keep her course and speed until collision cannot be
avoided by the give-way vessel alone.
- the stand-on vessel must continuously assess the situation and give warning
signal prescribed in Rule 34(d), subsequently, take action before collision
inevitable.
- Action should not be taken by the stand-on vessel without first
determining that ROC does in fact exist. Compass bearing and distance to
be checked accurately.
***e.g. no need to wait too long until approached 2nm in open sea
- Reduction of speed made by stand-on vessel may make more difficult for
the give-way vessel to cross astern, may be even more appropriate to
increase speed in certain circumstances.
-
(b) Action to be taken by the stand-on vessel (OOW duty)
- "When vessels are in sight of one another, any vessel fails to understand
the intentions or actions of an approaching vessel, or is in doubt whether
the other is taking sufficient action to avoid collision, is required by Rule
34(d) to immediately indicate such doubt by giving at least 5 short and
rapid blasts on the whistle, may be supplemented by at least 5 short and
rapid flashes"
 65
- wake-up signal should be made especially at distances over 2 miles.
- if these signals bring no immediate response: -
o calling master;
o changing auto to manual steering (if auto mode);
o engines on stand-by.
- the stand-on vessel may take action but should avoid taking action likely to
conflict with the give-way vessel.

Rule 17(c) not alter course to port

 situation for two PDVs crossing as described in Rule 15;
 in Rule 15, the give-way vessel is required to avoid crossing ahead and
likely to turn to starboard.
 an alteration course to port may also be dangerous for stand-on vessel.
 Generally, an alteration of course away from the direction of the other
vessel may be the safest manoeuvre, if made in sufficient time.
Compulsory action by the stand-on vessel
 If so close that collision cannot be avoided by the give-way vessel alone,
stand-on vessel is required to take action.
 Distance between vessels may vary with the approaching direction and
speed, and manoeuvring characteristics – generally be 4 times the
length of the give-way vessel.
 Rule 17(c) does not apply at this stage, a PDV is permitted to turn to port
for another PDV on the port bow. In this time turning towards the other
vessel may be the best action to take at close quarters if one vessel appears
likely to strike the other abaft the beam, as shown in Fig.
 66
 If collision with another vessel is inevitable, ship must be manoeuvred to
reduce collision effect as much as possible.
 impact with large angle – to be smaller angle
 near the mid length – to be glancing bow
 least serious if impact forward of collision bulkhead
 to bear in mind if approaching on port bow – worst action is alteration to
starboard

Rule 17(d) Obligation of the give-way vessel

- to emphasize the give-way vessel is not relieved of her obligation to take
early and substantial action passing at a safe distance.
- even if the stand-on vessel takes action in accordance with Rule 17(a)(ii) the
give-way vessel is not relieved of her obligation to keep out of the way.

FOUR stages in a collision situation

Stage-1: At long range before ROC exists, both vessels are free to take
any action.
Stage-2: When ROC first begins to apply, the give-way vessel is
required to take early and substantial action to achieve a safe
(5~8 miles)
passing distance and the stand-on vessel must keep her
course and speed.
Stage-3: When it becomes apparent that the give-way vessel is not
taking appropriate action in compliance with the Rules the
(2~3 miles)
stand-on vessel is required to give warning signal prescribed
in Rule 34(d) and is permitted to take action to avoid collision
by her manoeuvre alone. However, a PDV must not alter
course port to avoid another PDV crossing from her own port
side. The give-way vessel is not relieved of her obligation to
keep out of the way.
Stage-4: When collision cannot be avoided by the give-way vessel alone,
the stand-on vessel is required to take such action as will best
aid to avoid collision.
 67

4
3 Action required
2
1 Action permitted
Signal required

Keep course and speed

Before ROC,
free to take any action
 68
Rule 18
Responsibilities between vessels
Except where Rules 9, 10 and 13 otherwise require:
(a) A power-driven vessel underway shall keep out of the way of:
(i) a vessel not under command;
(ii) a vessel restricted in her ability to manoeuvre;
(iii) a vessel engaged in fishing;
(iv) a sailing vessel.
(b) A sailing vessel underway shall keep out of the way of:
(i) a vessel not under command;
(ii) a vessel restricted in her ability to manoeuvre;
(iii) a vessel engaged in fishing.
(c) A vessel engaged in fishing when underway shall, so far as possible,
keep out of the way of:
(i) a vessel not under command;
(ii) a vessel restricted in her ability to manoeuvre.
(d) (i) Any vessel other than a vessel not under command or a
vessel restricted in her ability to manoeuvre shall, if the
circumstances of the case admit, avoid impeding the safe passage
of a vessel constrained by her draught, exhibiting the signals in
Rule 28.
(ii) A vessel constrained by her draught shall navigate with
particular caution having full regard to her special condition.
(e) A seaplane on the water shall, in general, keep well clear of all vessels
and avoid impeding their navigation. In circumstances, however, where
risk of collision exists, she shall comply with the Rules of this part.

(f) (i) A WIG craft shall, when taking off, landing and in flight
near the surface, keep well clear of all other vessels and avoid
impeding their navigation;
(ii) A WIG craft operating on the water surface shall comply with the
Rules of this Part as a power-driven vessel.
 69

COMMENT:
Except where Rules 9, 10 and 13 otherwise require

- Sailing vessels, vessels <20m and fishing vessels must comply with Rules 9(b),(c), &
10(i),(j) which Rules are mainly concerned with not to impede.
- PDV following traffic lane or proceeding along a narrow channel must comply with
Rule 18 when ROC exists.
- In addition, Rule 13 overrides Rule 18. According to Rule 17(a)(ii), the vessel being
overtaken should take action to avoid collision by her own manoeuvre when
become apparent that the overtaking vessel is not taking appropriate action.

Categories of vessels
- certain category of privileged vessels for the purpose of Rule 18 are relevant
definition of Rule 3 and showing appropriate lights and shapes prescribed in Part
C.

- If signals of hampered vessels may not be easily recognized in time so avoiding

action not taken by a PDV, the privileged vessel must give warning signal
prescribed in Rule 34(d) and take avoiding action in accordance with Rule 17(a)(ii).

Action to be taken when Rule 18 applies

 Vessel required to keep out of the way (give-way vessel) must take early and
substantial action to result in passing at a safe distance, but is not required to
avoid crossing ahead.

The privileged vessel (stand-on vessel) is required to keep her course and speed in
accordance with Rule 17(a)(i).

Power-driven vessel

- includes a PDV lying stopped but 'under command'.

PVD – VCD crossing

- In crossing situation in which a PDV has a VCD on her own port side, the PDV must
take early action to allow the safe passage of VCD.
- If the VCD's signals are not recognized at long range so that ROC involved and VCD
become the 'give-way vessel'.

- However by complying with Rule 8(f)(ii) when taking action, the PDV should, have
full regard to the action which may be taken by VCD, and should avoid altering
course to port in accordance with 17(a)(ii) and 17(c).
 70
IMO guidance – Clarification of relation between
Rule 18(d) and rules of Part B, Sections II & III.
 A vessel constrained by her draft shall, when risk of collision with another vessel in a
crossing or head-on situation exists, apply the relevant Steering and Sailing Rules as a
power-driven vessel.

Local Rules

- Some local authorities have made special rules, which give additional privileged to
a vessel constrained by her draft so that she does not become a give-way vessel.

- Sailing Directions and other publications should be consulted for details of such
special rules.

Two hampered vessels involved in situation

- In case of two hampered vessels – ROC situation, degree of responsibility is not
established, each vessel should take whatever action she can avoid collision.

- Alteration of course should preferably be in accordance with the principles of Rules

14, 15 and 17(c).

Seaplanes, hovercraft and hydrofoils

 Rule 18(e) – seaplanes must keep well clear of all vessels and avoid impeding their
navigation, but must comply with Rules of Part B when ROC exists.
 Hovercraft and hydrofoils – not classed as seaplanes, even when operating in
non-displacement mode, but considered as power-driven vessels.

 Good seamanship – hovercraft & hydrofoils proceeding at high speed to take early
action to keep well clear.

 Air-cushion vessels operating in non-displacement mode may have drift angle of as

much as 45º due to wind effect, so Rule 23(b) requires to exhibit an all-round
flashing yellow light in addition to the lights for a PDV underway.

WIG craft

 18(f)(i) & 23(c) – requires an additional "high intensity all-round flashing red
light" when a WIG craft when taking-off, landing and in flight near the surface.
 18(f)(ii) – not required additional light but comply as a PDV.
 71
Section III – Conduct of vessels in restricted visibility

Rule 19
Conduct of vessels in restricted visibility
(a) This Rule applies to vessels not in sight of one another when
navigating in or near an area of restricted visibility.
(b) Every vessel shall proceed at a safe speed adapted to the
prevailing circumstances and conditions of restricted visibility. A
power-driven vessel shall have her engines ready for immediate
manoeuvre.
(c) Every vessel shall have due regard to the prevailing
circumstances and conditions of restricted visibility when
complying with the Rules of Section I of this part.
(d) A vessel which detects by radar alone the presence of another
vessel shall determine if a close-quarters situation is developing
and/or risk of collision exists. If so, she shall take avoiding action
in ample time, provided that when such action consists of an
alteration of course, so far as possible the following shall be
avoided:
(i) an alteration of course to port for a vessel forward of the
beam, other than for a vessel being overtaken;
(ii) an alteration of course towards a vessel abeam or abaft the
beam.
(e) Except where it has been determined that a risk of collision does
not exist, every vessel which hears apparently forward of her
beam the fog signal of another vessel, or which cannot avoid a
close-quarters situation with another vessel forward of her beam,
shall reduce her speed to the minimum at which she can be kept
on her course. She shall if necessary take all her way off and in
any event navigate with extreme caution until danger of collision
is over.
 72
Vessels not in sight of one another and in or near an area of restricted
visibility (RV)

- Rule 19 applies to vessels

i. not in sight of one another and
ii. navigating not only in RV but also near such area.

- 19(c) emphasizes to take RV into account when complying Rules of Section

I of Part B.

Preparation for entering RV (Essential 6 points)

(1). Switch-on navigation lights (Rule 20)
(2). Sound fog signals (Rule 35)
(3). Post extra look-outs – silence on deck (Rule 5)
(4). Engines stand-by – proceed at a safe speed (Rule 6 & 19(b))
(5). Operate radar – detect by radar-plotting (Rule 7&19(d))
(6). Switch Auto-to-Manual steering (if auto mode) (Rule 8)
***Other measures to be considered on entering RV: - such as calling master.
***Narrow channels and TSS (Rule 9 & 10) also apply in all condition of
visibility.

Detects by radar alone

- detects by radar only (without sighting visually or hearing fog signals)
- If the vessel detected comes visual sight, or a fog signal is heard forward of
the beam, appropriate rule must be complied with.
- essential to keep good look-out by sight and hearing in addition to radar-
plotting.
- to determine whether close-quarters situation is developing and/or ROC
exists.
 73

Close-quarters situation
- In RV, in open sea, a close-quarters situation is generally considered to
begin to apply at least 2 miles in any direction forward of the beam (as a
range of audibility) – sometimes may be minimum 3 miles.

HEADING MARKER
12 m

8m

4m

CLOSE
QUARTERS
SITUATION

Taking avoiding action in ample time

 As general guidance, in open sea using 12 miles range scale, radar

observation should be assessed an approaching target at earlier stage of
distance before 4 nm. If a close quarters situation is developing or ROC
exists, substantial action should be taken before the target reaches 4 miles
range.
 19(d) requires avoiding action to be taken in ample time, but for a vessel
being overtaken permitted to keep her course and speed when a close
quarters situation is developing.
 Rules of Part B, Section II only apply to vessels in sight of one another.
 Approaching from abaft the beam – relatively slow rate.
 74

Action consists of an alteration of course

(d)(i) Avoid alteration to port for a vessel forward of the beam, however,
alteration to port or starboard is allowed for a vessel being
overtaken forward of the beam.
(d)(ii) Avoid alteration towards a vessel abeam or abaft the beam.

Ahead

 An alteration in either direction is permitted when a vessel approaches

from astern.

Change of speed to avoid close quarters situation

- change of speed can be made to avoid if close quarters situation is

developing and ROC exists.
- more effective when vessel approaching from nearly abeam
- speed may be slackened to allow more time to assess the situation (Rule
8(e)).
 75

19(e) where risk of collision does not exist

FOG SIGNAL but not radar detect

 Rule 19(d) & Rule 7 require ROC to be determined by radar plotting for
ranges and bearings.
 The possibility of fog signal may be heard from different vessel must also
be taken into account.
 If it has been determined that ROC does not exist, a vessel is not required
to reduce her speed to the minimum.
 Fog signal might be from: -
- a vessel being overtaken, or
- a vessel coming down in opposite direction on correct sides of a narrow
channel, or
- ship's whistle can be heard at longer distances.

 If the fog signal of anchored vessel is heard apparent forward of the beam,
and previously not detected by radar, the engines must be stopped and
taken off if necessary.
(i.e. it has not been determined that ROC not exists)

RADAR DETECT - cannot avoid a close quarters situation

- if a vessel is unable to avoid a close quarters situation (due to lack of sea

room or action taken by other vessel), she must reduce speed in ample
time without waiting until a close quarters situation to develop.

shall reduce her speed

(i) Where the position of vessel whose made fog signal forward of the beam
has not been ascertained, or
(ii) when a close quarters situation could not be avoided with a vessel forward
of the beam: -
 should stop engines – advantage for hearing fog signal
 76

navigate with extreme caution

 Generally, alteration of course should be avoided after hearing a fog
signal forward of the beam, unless both positions and movement have
been determined.
 The direction of the sound signal may be misleading in fog.
 Even if a signal heard forward of the beam is changed to two prolong
blasts of a vessel not making way, an alteration course may not be justified.

if necessary take all way off

If vessels navigating without operational radar should take all way off
after hearing the following fog signals: -
a. when the first time heard the signal in close proximity;
b. where the signal heard dead ahead;
c. where the signals heard narrowing / fine bow;
d. vessel seen loom out of the fog, but her course not immediately apparent;
e. anchor signal and tide set towards her;
f. Fog signal – Morse code "D" heard forward of the beam.

 when unnecessarily full astern, noise may disturb hearing.

Last minutes option

 whenever making reverse engines, keep in mind: -
o the effect of transverse thrust; and
o slew action by wind effect due to pivot point shifted.
 if the imminent collision is unavoidable, rudder hard over to keep
the bow pointing towards the approaching vessel.
 77

PART C – LIGHTS AND SHAPES

Rule 20
Application

(a) Rules in this part shall be complied with in all weathers.

(b) The Rules concerning lights shall be complied with from sunset to
sunrise, and during such times no other lights shall be exhibited, except
such lights as cannot be mistaken for the lights specified in these Rules
or do not impair their visibility or distinctive character, or interfere with
the keeping of a proper look-out.
(c) The lights prescribed by these Rules shall, if carried, also be exhibited
from sunrise to sunset in restricted visibility and may be exhibited in
all other circumstances when it is deemed necessary.
(d) The Rules concerning shapes shall be complied with by day.
(e) The lights and shapes specified in these Rules shall comply with the
provisions of Annex I to these Regulations.
 78
Rule 21
Definitions

(a) Masthead light means a white light placed over the fore and aft
centreline of the vessel showing an unbroken light over an arc of the
horizon of 225˚ and so fixed as to show the light from right ahead to
22.5˚ abaft the beam on either side of the vessel.
(b) Sidelights means a green light on the starboard side and a red light on
the port side each showing an unbroken light over an arc of the horizon
of 112.5˚ and so fixed as to show the light from right ahead to 22.5˚
abaft the beam on its respective side. In a vessel of less than 20 m in
length the sidelights may be combined in one lantern carried on the
fore and aft centreline of the vessel.
(c) Sternlight means a white light placed as nearly as practicable at the
stern showing an unbroken light over an arc of the horizon of 135˚ and
so fixed as to show the light 67.5˚ from right aft on each side of the
vessel.
(d) Towing light means a yellow light having the same characteristics as
the sternlight defined in paragraph (c) of this Rule.
(e) All-round light means a light showing an unbroken light over an arc of
the horizon of 360 degrees.
(f) Flashing light means a light flashing at regular intervals at a frequency
of 120 flashes or more per minute.
 79
Rule 22
Visibility of lights
The lights prescribed in these Rules shall have an intensity as specified in
section 8 of Annex I to these Regulations so as to be visible at the following
minimum ranges:
(a) In vessels of 50 m or more in length:
- a masthead light, 6 miles;
- a sidelight, 3 miles;
- a sternlight, 3 miles;
- a towing light, 3 miles;
- a white, red, green or yellow all-round light, 3 miles.
(b) In vessels of 12 m or more in length but less than 50 m in length;
- a masthead light, 5 miles; except that where the length of the
vessel is less than 20 m, 3 miles;
- a sidelight, 2 miles;
- a sternlight, 2 miles;
- a towing light, 2 miles;
- a white, red, green or yellow all-round light, 2 miles.
(c) In vessels of less than 12 m in length:
- a masthead light, 2 miles;
- a sidelight, 1 mile;
- a sternlight, 2 miles;
- a towing light, 2 miles;
- a white, red, green or yellow all-round light, 2 miles.
(d) In inconspicuous, partly submerged vessels or objects being towed:
- a white all-round light, 3 miles.
 80
Rule 23
Power-driven vessels underway
(a) A power-driven vessel underway shall exhibit:
(i) a masthead light forward;
(ii) a second masthead light abaft of and higher than the forward one;
except that a vessel of less than 50 m in length shall not be obliged
to exhibit such light but may do so;
(iii) sidelights;
(iv) a sternlight.
(b) An air-cushion vessel when operating in the non-displacement mode
shall, in addition to the lights prescribed in paragraph (a) of this Rule,
exhibit an all-round flashing yellow light.
(c) A WIG craft only when taking off, landing and in flight near the surface
shall, in addition to the lights prescribed in paragraph (a) of this Rule,
exhibit a high intensity all-round flashing red light.
(d) (i) A power-driven vessel of less than 12 m in length may in lieu of the
lights prescribed in paragraph (a) of this Rule exhibit an all-round
white light and sidelights;
(ii) a power-driven vessel of less than 7 m in length whose maximum
speed does not exceed 7 knots may in lieu of the lights prescribed
in paragraph (a) of this Rule exhibit an all-round white light and
shall, if practicable, also exhibit sidelights;
(iii) the masthead light or all-round white light on a power-driven
vessel of less than 12 m in length may be displaced from the fore
and aft centreline of the vessel if centreline fitting is not
practicable, provided that the sidelights are combined in one
lantern which shall be carried on the fore and aft centreline of the
vessel or located as nearly as practicable in the same fore and aft
line as the masthead light or the all-round white light.
 81

Rule 24
Towing and pushing
(a) A power-driven vessel when towing shall exhibit:
(i) instead of the light prescribed in Rule 23(a)(i) or (a)(ii), two
masthead lights in a vertical line. When the length of the tow,
measuring from the stern of the towing vessel to the after end of
the tow exceeds 200 m, three such lights in a vertical line;
(ii) sidelights;
(iii) a sternlight;
(iv) a towing light in a vertical line above the sternlight;
(v) when the length of the tow exceeds 200 m, a diamond shape
where it can best be seen.
(b) When a pushing vessel and a vessel being pushed ahead are rigidly
connected in a composite unit they shall be regarded as a power-driven
vessel and exhibit the lights prescribed in Rule 23.
(c) A power-driven vessel when pushing ahead or towing alongside, except
in the case of a composite unit, shall exhibit:
(i) instead of the light prescribed in Rule 23(a)(i) or (a)(ii), two
masthead lights in a vertical line;
(ii) sidelights;
(iii) a sternlight.
(d) A power-driven vessel to which paragraph (a) or (c) of this Rule applies
shall also comply with Rule 23(a)(ii).
(e) A vessel or object being towed, other than those mentioned in
paragraph (g) of this Rule, shall exhibit:
(i) sidelights;
(ii) a sternlight;
(iii) when the length of the tow exceeds 200 m, a diamond shape
where it can best be seen.
 82
(f) Provided that any number of vessels being towed alongside or pushed
in a group shall be lighted as one vessel,
(i) a vessel being pushed ahead, not being part of a composite unit,
shall exhibit at the forward end, sidelights;
(ii) a vessel being towed alongside shall exhibit a sternlight and at the
forward end, sidelights.
(g) An inconspicuous, partly submerged vessel or object, or combination of
such vessels or objects being towed, shall exibit:
(i) if it is less than 25 m in breadth, one all-round white light at or
near the forward end and one at or near the after end except that
dracones need not exhibit a light at or near the forward end;
(ii) if it is 25 m or more in breadth, two additional all-round white
lights at or near the extremities of its breadth;
(iii) if it exceeds 100 m in length, additional all-round white lights
between the lights prescribed in subparagraphs (i) and (ii) so that
the distance between the lights shall not exceed 100 m;
(iv) a diamond shape at or near the aftermost extremity of the last
vessel or object being towed and if the length of the tow exceeds
200 m an additional diamond shape where it can best be seen and
located as far forward as is practicable.
(h) Where from any sufficient cause it is impracticable for a vessel or object
being towed to exhibit the lights or shapes prescribed in paragraph (e)
or (g) of this Rule, all possible measures shall be taken to light the vessel
or object towed or at least to indicate the presence of such vessel or
object.
(i) Where from any sufficient cause it is impracticable for a vessel not
normally engaged in towing operations to display the lights prescribed
in paragraph (a) or (c) of this Rule, such vessel shall not be required to
exhibit those lights when engaged in towing another vessel in distress
or otherwise in need of assistance. All possible measures shall be taken
to indicate the nature of the relationship between the towing vessel and
the vessel being towed as authorized by Rule 36, in particular by
illuminating the towline.
 83

Rule 25
Sailing vessels underway and vessels under oars

(a) A sailing vessel underway shall exhibit:

(i) sidelights;
(ii) a sternlight.
(b) In a sailing vessel of less than 20 m in length the lights prescribed in
paragraph (a) of this Rule may be combined in one lantern carried at or
near the top of the mast where it can best be seen.
(c) A sailing vessel underway may, in addition to the lights prescribed in
paragraph (a) of this Rule, exhibit at or near the top of the mast, where
they can best be seen, two all-round lights in a vertical line, the upper
being red and the lower green, but these lights shall not be exhibited in
conjunction with the combined lantern permitted by paragraph (b) of
this Rule.
(d) (i) A sailing vessel of less than 7 m in length shall, if practicable,
exhibit the lights prescribed in paragraph (a) or (b) of this Rule, but
if she does not, she shall have ready at hand an electric torch or
lighted lantern showing a white light which shall be exhibited in
sufficient time to prevent collision.
(iv) A vessel under oars may exhibit the lights prescribed in this Rule
for sailing vessels, but if she does not, she shall have ready at hand
an electric torch or lighted lantern showing a white light which
shall be exhibited in sufficient time to prevent collision.
(e) A vessel proceeding under sail when also being propelled by machinery
shall exhibit forward where it can best be seen a conical shape, apex
downwards.
 84

Rule 26
Fishing vessels

(a) A vessel engaged in fishing, whether underway or at anchor, shall

exhibit only the lights and shapes prescribed in this Rule.
(b) A vessel when engaged in trawling, by which is meant the dragging
through the water of a dredge net or other apparatus used as a fishing
appliance, shall exhibit:
(i) two all-round lights in a vertical line, the upper being green and
the lower white, or a shape consisting of two cones with their
apexes together in a vertical line one above the other;
(ii) a masthead light abaft of and higher than the all-round green light;
a vessel of less than 50 m in length shall not be obliged to exhibit
such a light but may do so;
(iii) when making way through the water, in addition to the lights
prescribed in this paragraph, sidelights and a sternlight.
(c) A vessel engaged in fishing, other than trawling shall exhibit:
(i) two all-round lights in a vertical line, the upper being red and the
lower white, or a shape consisting of two cones with apexes
together in a vertical line one above the other;
(ii) when there is outlying gear extending more than 150 m
horizontally from the vessel, an all-round white light or a cone apex
upwards in the direction of the gear;
(iii) when making way through the water, in addition to the lights
prescribed in this paragraph, sidelights and a sternlight.
(d) The additional signals described in Annex II to these regulations apply
to a vessel engaged in fishing in close proximity to other vessels
engaged in fishing.
(e) A vessel when not engaged in fishing shall not exhibit the lights or
shapes prescribed in this Rule, but only those prescribed for a vessel of
her length.
 85

Rule 27
Vessels not under command or restricted in their ability to
manoeuvre

(a) A vessel not under command shall exhibit:

(i) two all-round red lights in a vertical line where they can best be
seen;
(ii) two balls or similar shapes in a vertical line where they can best be
seen;
(iii) when making way through the water, in addition to the lights
prescribed in this paragraph, sidelights and a sternlight.
(b) A vessel restricted in her ability to manoeuvre, except a vessel engaged
in mine clearance operations, shall exhibit:
(i) three all-round lights in a vertical line where they can best be seen.
The highest and lowest of these lights shall be red and the middle
light shall be white;
(ii) three shapes in a vertical line where they can best be seen. The
highest and lowest of these shapes shall be balls and the middle
one a diamond;
(iii) when making way through the water, a masthead light or lights,
sidelights and a sternlight, in addition to the lights prescribed in
sub-paragraph (i);
(iv) when at anchor, in addition to the lights or shapes prescribed in
sub-paragraphs (i) and (ii), the light, lights or shape prescribed in
Rule 30.
(c) A power-driven vessel engaged in a towing operation such as severely
restricts the towing vessel and her tow in their ability to deviate from
their course shall, in addition to the lights or shapes prescribed in Rule
24(a), exhibit the lights or shapes prescribed in subparagraphs (b)(i) and
(ii) of this Rule.
 86

(d) A vessel engaged in dredging or underwater operations, when restricted

in her ability to manoeuvre, shall exhibit the lights and shapes
prescribed in subparagraphs (b)(i), (ii) and (iii) of this Rule and shall in
addition, when an obstruction exists, exhibit:
(i) two all-round red lights or two balls in a vertical line to indicate the
side on which the obstruction exists;
(ii) two all-round green lights or two diamonds in a vertical line to
indicate the side on which another vessel may pass;
(iii) when at anchor, the lights or shapes prescribed in this paragraph
instead of the lights or shape prescribed in Rule 30.
(e) Whenever the size of a vessel engaged in diving operations makes it
impracticable to exhibit all lights and shapes prescribed in paragraph (d)
of this Rule, the following shall be exhibited:
(i) three all-round lights in a vertical line where they can best be seen.
The highest and lowest of these lights shall be red and the middle
light shall be white;
(ii) a rigid replica of the International Code flag “A” not less than 1 m
in height. Measures shall be taken to ensure its all-round visibility.
(f) A vessel engaged in mine clearance operations shall in addition to the
lights prescribed for a power-driven vessel in Rule 23 or to the lights or
shape prescribed for a vessel at anchor in Rule 30 as appropriate,
exhibit three all-round green lights or three balls. One of these lights or
shapes shall be exhibited near the foremast head and one at each end
of the fore yard. These lights or shapes indicate that it is dangerous for
another vessel to approach within 1000 m of the mine clearance vessel.
(g) Vessels of less than 12 m in length, except those engaged in diving
operations, shall not be required to exhibit the lights and shapes
prescribed in this Rule.
(h) The signals prescribed in this Rule are not signals of vessels in distress
and requiring assistance. Such signals are contained in Annex IV to
these Regulations.
 87

Rule 28
Vessels constrained by their draught
A vessel constrained by her draught may, in addition to the lights prescribed
for power-driven vessels in Rule 23, exhibit where they can best be seen three
all-round red lights in a vertical line, or a cylinder.

Rule 29
Pilot vessels
(a) A vessel engaged on pilotage duty shall exhibit:
(i) at or near the masthead, two all-round lights in a vertical line, the
upper being white and the lower red;
(ii) when underway, in addition, sidelights and a sternlight;
(iii) when at anchor, in addition to the lights prescribed in
subparagraph (i), the light, lights or shape prescribed in Rule 30 for
vessels at anchor.
(b) A pilot vessel when not engaged on pilotage duty shall exhibit the lights
or shapes prescribed for a similar vessel of her length.

Rule 30
Anchored vessels and vessels aground
(a) A vessel at anchor shall exhibit where it can best be seen:
(i) in the fore part, an all-round white light or one ball;
(ii) at or near the stern and at a lower level than the light prescribed in
subparagraph (i), an all-round white light.
(b) A vessel of less than 50 m in length may exhibit an all-round white light
where it can best be seen instead of the lights prescribed in paragraph
(a) of this Rule.
(c) A vessel at anchor may, and a vessel of 100 m and more in length, shall
also use the available working or equivalent lights to illuminate her
decks.
 88
(d) A vessel aground shall exhibit the lights prescribed in paragraph (a) or
(b) of this Rule and in addition, where they can best be seen:
(i) two all-round red lights in a vertical line;
(ii) three balls in a vertical line.
(e) A vessel of less than 7 m in length, when at anchor, not in or near a
narrow channel, fairway or anchorage, or where other vessels normally
navigate, shall not be required to exhibit the lights or shape prescribed
in paragraphs (a) and (b) of this Rule.
(f) A vessel of less than 12 m in length, when aground, shall not be
required to exhibit the lights or shapes prescribed in subparagraphs
(d)(i) and (ii) of this Rule.

Rule 31
Seaplanes
Where it is impracticable for a seaplane or a WIG craft to exhibit lights and
shapes of the characteristics or in the positions prescribed in the Rules of this
Part she shall exhibit lights and shapes as closely similar in characteristics and
position as is possible.

Rule 32
Definitions
(a) The word “whistle” means any sound signalling appliance capable of
producing the prescribed blasts and which complies with the
specifications in Annex III to these Regulations.
(b) The term “short blast” means a blast of about one second’s duration.
(c) The term “prolonged blast” means a blast of from four to six seconds’
duration.
 89

Rule 33
Equipment for sound signals
(a) A vessel of 12 m or more in length shall be provided with a whistle, a
vessel of 20 m or more in length shall be provided with a bell in
addition to a whistle, and a vessel of 100 meters or more in length shall,
in addition, be provided with a gong, the tone and sound of which
cannot be confused with that of the bell. The whistle, bell and gong
shall comply with the specification in Annex III to these regulations. The
bell or gong or both may be replaced by other equipment having the
same respective sound characteristics, provided that manual sounding
of the required signals shall always be possible.
(b) A vessel of less than 12 m in length shall not be obliged to carry the
sound signalling appliances prescribed in paragraph (a) of this Rule but
if she does not, she shall be provided with some other means of making
an efficient sound signal.

Rule 34
Manoeuvring and warning signals
(a) When vessels are in sight of one another, a power-driven vessel
underway, when manoeuvring as authorized or required by these Rules,
shall indicate that manoeuvre by the following signals on her whistle:
- one short blast to mean “I am altering my course to starboard”;
- two short blasts to mean “I am altering my course to port”;
- three short blasts to mean “I am operating astern propulsion”.
(b) Any vessel may supplement the whistle signals prescribed in paragraph
(a) of this Rule by light signals, repeated as appropriate, whilst the
manoeuvre is being carried out:
(i) these light signals shall have the following significance:
- one flash to mean “I am altering my course to starboard”;
- two flashes to mean “I am altering my course to port”;
- three flashes to mean “I am operating astern propulsion”;
 90
(ii) the duration of each flash shall be about one second, the interval
between flashes shall be about one second, and the interval
between successive signals shall be not less than ten seconds;
(iii) the light used for this signal shall, if fitted, be an all-round white
light, visible at a minimum range of 5 miles, and shall comply with
the provisions of Annex I to these Regulations.
(c) When in sight of one another in a narrow channel or fairway:
(i) a vessel intending to overtake another shall in compliance with
Rule 9(e)(i) indicate her intention by the following signals on her
whistle:
- two prolonged blasts followed by one short blast to mean “I
intend to overtake you on your starboard side”;
- two prolonged blasts followed by two short blasts to mean “I
intend to overtake you on your port side”.
(ii) the vessel about to be overtaken when acting in accordance with
Rule 9(e)(i) shall indicate her agreement by the following signal on
her whistle:
- one prolonged, one short, one prolonged and one short blast,
in that order.
(d) When vessels in sight of one another are approaching each other and
from any cause either vessel fails to understand the intentions or
actions of the other, or is in doubt whether sufficient action is being
taken by the other to avoid collision, the vessel in doubt shall immediately
indicate such doubt by giving at least five short and rapid blasts on the
whistle. Such signal may be supplemented by a light signal of at least five
short and rapid flashes.
(e) A vessel nearing a bend or an area of a channel or fairway where other
vessels may be obscured by an intervening obstruction shall sound one
prolonged blast. Such signal shall be answered with a prolonged blast
by any approaching vessel that may be within hearing around the bend
or behind the intervening obstruction.
(f) If whistles are fitted on a vessel at a distance apart of more than 100
m, one whistle only shall be used for giving manoeuvring and warning
signals.
 91
Rule 35
Sound signals in restricted visibility
In or near an area of restricted visibility, whether by day or night, the signals
prescribed in this Rule shall be used as follows:
(a) A power-driven vessel making way through the water shall sound at
intervals of not more than 2 minutes one prolonged blast.
(b) A power-driven vessel underway but stopped and making no way
through the water shall sound at intervals of not more than 2 minutes
two prolonged blasts in succession with an interval of about 2 seconds
between them.
(c) A vessel not under command, a vessel restricted in her ability to
manoeuvre, a vessel constrained by her draught, a sailing vessel, a
vessel engaged in fishing and a vessel engaged in towing or pushing
another vessel shall, instead of the signals prescribed in paragraphs (a)
or (b) of this Rule, sound at intervals of not more than 2 minutes three
blasts in succession, namely one prolonged followed by two short blasts.
(d) A vessel engaged in fishing, when at anchor, and a vessel restricted in
her ability to manoeuvre when carrying out her work at anchor, shall
instead of the signals prescribed in paragraph (g) of this Rule sound the
signal prescribed in paragraph (c) of this Rule.
(e) A vessel towed or if more than one vessel is towed the last vessel of the
tow, if manned, shall at intervals of not more than 2 minutes sound four
blasts in succession, namely one prolonged followed by three short blasts.
When practicable, this signal shall be made immediately after the signal
made by the towing vessel.
(f) When a pushing vessel and a vessel being pushed ahead are rigidly
connected in a composite unit they shall be regarded as a power-driven
vessel and shall give the signals prescribed in paragraphs (a) or (b) of
this Rule.
(g) A vessel at anchor shall at intervals of not more than one minute ring the
bell rapidly for about 5 seconds. In a vessel of 100 m or more in length
the bell shall be sounded in the forepart of the vessel and immediately
after the ringing of the bell the gong shall be sounded rapidly for about 5
seconds in the after part of the vessel. A vessel at anchor may in addition
sound three blasts in succession, namely one short, one prolonged and
 92
one short blast, to give warning of her position and of the possibility of
collision to an approaching vessel.
(h) A vessel aground shall give the bell signal and if required the gong
signal prescribed in paragraph (g) of this Rule and shall, in addition, give
three separate and distinct strokes on the bell immediately before and
after the rapid ringing of the bell. A vessel aground may in addition
sound an appropriate whistle signal.
(i) A vessel of 12 m or more but less than 20 m in length shall not be
obliged to give the bell signals prescribed in paragraphs (g) and (h) of
this Rule. However, if she does not, she shall make some other efficient
sound signal at intervals of not more than 2 minutes.
(j) A vessel of less than 12 m in length shall not be obliged to give the
above-mentioned signals but, if she does not, shall make some other
efficient sound signal at intervals of not more than 2 minutes.
(k) A pilot vessel when engaged on pilotage duty may in addition to the
signals prescribed in paragraphs (a), (b) or (g) of this Rule sound an
identity signal consisting of four short blasts.

Rule 36
Signals to attract attention
If necessary to attract the attention of another vessel any vessel may make
light or sound signals that cannot be mistaken for any signal authorized
elsewhere in these Rules, or may direct the beam of her searchlight in the
direction of the danger, in such a way as not to embarrass any vessel. Any light
to attract the attention of another vessel shall be such that it cannot be
mistaken for any aid to navigation. For the purpose of this Rule the use of high
intensity intermittent or revolving lights, such as strobe lights, shall be
avoided.

Rule 37
Distress signals
When a vessel is in distress and requires assistance she shall use or exhibit the
signals described in Annex IV to these Regulations.
 93
Rule 38
Exemptions
Any vessel (or class of vessels) provided that she complies with the
requirements of the International Regulations for Preventing Collisions at Sea,
1960, the keel of which is laid or which is at a corresponding stage of
construction before the entry into force of these Regulations may be
exempted from compliance therewith as follows:
(a) The installation of lights with ranges prescribed in Rule 22, until four
years after the date of entry into force of these Regulations.
(b) The installation of lights with colour specifications as prescribed in
section 7 of Annex I to these Regulations, until four years after the date
of entry into force of these Regulations.
(c) The repositioning of lights as a result of conversion from Imperial to
metric units and rounding off measurement figures, permanent
exemption.
(d) (i) The repositioning of masthead lights on vessels of less than 150 m
in length, resulting from the prescriptions of section 3(a) of
Annex I to these Regulations, permanent exemption.
(ii) The repositioning of masthead lights on vessels of 150 m or more
in length, resulting from the prescriptions of section 3(a) of
Annex I to these Regulations, until nine years after the date of
entry into force of these Regulations.
(e) The repositioning of masthead lights resulting from the prescriptions of
Section 2(b) of Annex I to these Regulations, until nine years after the
date of entry into force of these Regulations.
(f) The repositioning of sidelights resulting from the prescriptions of
sections 2(g) and 3(b) of Annex I to these Regulations, until nine
years after the date of entry into force of these Regulations.
(g) The requirements for sound signal appliances prescribed in Annex III to
these Regulations, until nine years after the date of entry into force of
these Regulations.
(h) The repositioning of all-round lights resulting from the prescription of
section 9(b) of Annex I to these Regulations, permanent exemption.
 94
Annex I
Positioning and Technical Details of Lights and Shapes

1 Definition
The term “height above the hull” means height above the uppermost continuous
deck. This height shall be measured from the position vertically beneath the location of
the light.

2 Vertical positioning and spacing of lights

(a) On a power-driven vessel of 20 m or more in length the masthead lights shall

be placed as follows:
(i) the forward masthead light, or if only one masthead light is carried, then
that light, at a height above the hull of not less than 6 m, and, if the
breadth of the vessel exceeds 6 m, then at a height above the hull not less
than such breadth, so however that the light need not be placed at a
greater height above the hull than 12 m;
(ii) when two masthead lights are carried the after one shall be at least 4.5 m
vertically higher than the forward one.

(b) The vertical separation of masthead lights of power-driven vessels shall be such
that in all normal conditions of trim the after light will be seen over and
separate from the forward light at a distance of 1000 m from the stem when
viewed from sea-level.

(c) The masthead light of a power-driven vessel of 12 m but less than 20 m in

length shall be placed at a height above the gunwale of not less than 2.5 m.
(d) A power-driven vessel of less than 12 m in length may carry the uppermost light
at a height of less than 2.5 m above the gunwale. When however a masthead
light is carried in addition to sidelights and a sternlight or the all-round light
prescribed in Rule 23(c)(i) is carried in addition to sidelights, then such
masthead light or all-round light shall be carried at least 1 m higher than the
sidelights.

(e) One of the two or three masthead lights prescribed for a power-driven vessel
when engaged in towing or pushing another vessel shall be placed in the same
position as either the forward masthead light or the after masthead light;
provided that, if carried on the aftermast, the lowest after masthead light shall
be at least 4.5 m vertically higher than the forward masthead light.
 95
(f) (i) The masthead light or lights prescribed in Rule 23(a) shall be so placed as
to be above and clear of all other lights and obstructions except as
described in subparagraph (ii).
(ii) When it is impracticable to carry the all-round lights prescribed by Rule
27(b)(i) or Rule 28 below the masthead lights, they may be carried above
the after masthead light(s) or vertically in between the forward masthead
light(s) and after masthead light(s), provided that in the latter case the
requirement of section 3(c) of this Annex shall be complied with.

(g) The sidelights of a power-driven vessel shall be placed at a height above the
hull not greater than three quarters of that of the forward masthead light. They
shall not be so low as to be interfered with by deck lights.
(h) The sidelights, if in a combined lantern and carried on a power-driven vessel of
less than 20 m in length, shall be placed not less than 1 m below the masthead
light.

(i) When the Rules prescribe two or three lights to be carried in a vertical line, they
shall be spaced as follows:
(i) on a vessel of 20 m in length or more such lights shall be spaced not less
than 2 m apart, and the lowest of these lights shall, except where a towing
light is required, be placed at a height of not less than 4 m above the hull;
(ii) on a vessel of less than 20 m in length such lights shall be spaced not less
than 1 m apart and the lowest of these lights shall, except where a towing
light is required, be placed at a height of not less than 2 m above the
gunwale;
(iii) when three lights are carried they shall be equally spaced.

(j) The lower of the two all-round lights prescribed for a vessel when engaged in
fishing shall be at a height above the sidelights not less than twice the distance
between the two vertical lights.
(k) The forward anchor light prescribed in Rule 30(a)(i), when two are carried, shall
not be less than 4.5 m above the after one. On a vessel of 50 m or more in
length this forward anchor light shall be placed at a height of not less than 6 m
above the hull.

3 Horizontal positioning and spacing of lights

(a) When two masthead lights are prescribed for a power-driven vessel, the
horizontal distance between them shall not be less than one half of the length
of the vessel but need not be more than 100 m. The forward light shall be
placed not more than one quarter of the length of the vessel from the stem.
 96
(b) On a power-driven vessel of 20 m or more in length the sidelights shall not be
placed in front of the forward masthead lights. They shall be placed at or near
the side of the vessel.
(c) When the lights prescribed in Rule 27(b)(i) or Rule 28 are placed vertically
between the forward masthead light(s) and the after masthead light(s) these all-
round lights shall be placed at a horizontal distance of not less than 2 m from
the fore and aft centreline of the vessel in the athwartship direction.
(d) When only one masthead light is prescribed for a power driven vessel, this light
shall be exhibited forward of amidships; except that a vessel of less than 20 m in
length need not exhibit this light forward of amidships but shall exhibit it as far
forward as is practicable.

4 Details of location of direction-indicating lights for fishing vessels,

dredgers and vessels engaged in underwater operations
(a) The light indicating the direction of the outlying gear from a vessel engaged in
fishing as prescribed in Rule 26(c)(ii) shall be placed at a horizontal distance of
not less than 2 m and not more than 6 m away from the two all-round red and
white lights. This light shall be placed not higher than the all-round white light
prescribed in Rule 26(c)(i) and not lower than the sidelights.
(b) The lights and shapes on a vessel engaged in dredging or underwater
operations to indicate the obstructed side and/or the side on which it is safe to
pass, as prescribed in Rule 27(d)(i) and (ii), shall be placed at the maximum
practical horizontal distance, but in no case less than 2 m, from the lights or
shapes prescribed in Rule 27(b)(i) and (ii). In no case shall the upper of these
lights or shapes be at a greater height than the lower of the three lights or
shapes prescribed in Rule 27(b)(i) and (ii).

5 Screens for sidelights

The sidelights of vessels of 20 m or more in length shall be fitted with inboard screens
painted matt black, and meeting the requirements of section 9 of this Annex. On
vessels of less than 20 m in length the sidelights, if necessary to meet the requirements
of section 9 of this Annex, shall be fitted with inboard matt black screens. With a
combined lantern, using a single vertical filament and a very narrow division between
the green and red sections, external screens need not be fitted.
 97
6 Shapes

(a) Shapes shall be black and of the following sizes:

(i) a ball shall have a diameter of not less than 0.6 m;

(ii) a cone shall have a base diameter of not less than 0.6 m and a height
equal to its diameter;

(iii) a cylinder shall have a diameter of at least 0.6 m and a height of twice its
diameter;
(iv) a diamond shape shall consist of two cones as defined in (ii) above having
a common base.

(b) The vertical distance between shapes shall be at least 1.5 m.

(c) In a vessel of less than 20 m in length shapes of lesser dimensions but

commensurate with the size of the vessel may be used and the distance apart
may be correspondingly reduced.

7 Colour specification of lights

The chromaticity of all navigation lights shall conform to the following standards, which
lie within the boundaries of the area of the diagram specified for each colour by the
International Commission on Illumination (CIE).

The boundaries of the area for each colour are given by indicating the corner co-
ordinates, which are as follows:
(i) White

X 0.525 0.525 0.452 0.310 0.310 0.443

Y 0.382 0.440 0.440 0.348 0.283 0.382

(iii) Green

X 0.028 0.009 0.300 0.203

Y 0.385 0.723 0.511 0.356

(iii) Red

X 0.680 0.660 0.735 0.721

Y 0.320 0.320 0.265 0.259

(iv) Yellow

X 0.612 0.618 0.575 0.575

Y 0.382 0.382 0.425 0.406

 98

8 Intensity of lights
(a) The minimum luminous intensity of lights shall be calculated by using the
formula:
6 -D
I = 3.43 x 10 x T x D x K
where I is luminous intensity in candelas under service conditions,

T is threshold factor 2 x 10-7 lux,

D is range of visibility (luminous range) of the light in nautical miles,

K is atmospheric transmissivity.

For prescribed lights the value of K shall be 0.8, corresponding to a meteorological

visibility of approximately 13 nautical miles.

(b) A selection of figures derived from the formula is given in the following table:

Range of visibility Luminous intensity of

(luminous range) of light in candelas for
light in nautical miles K = 0.8
I I
1 0.9
2 4.3
3 12
4 27
5 52
6 94

NOTE: The maximum luminous intensity of navigation lights should be limited to

avoid undue glare. This shall not be achieved by a variable control of the
luminous intensity.
 99

9 Horizontal sectors

(a) (i) In the forward direction, sidelights as fitted on the vessel shall show the
minimum required intensities. The intensities shall decrease to reach
practical cut-off between 1º and 3º outside the prescribed sectors.
(ii) For sternlights and masthead lights and at 22.5° abaft the beam for
sidelights, the minimum required intensities shall be maintained over the
arc of the horizon up to 5 º within the limits of the sectors prescribed in
Rule 21. From 5 º within the prescribed sectors the intensity may decrease
by 50 per cent up to the prescribed limits; it shall decrease steadily to
reach practical cut-off at not more than 5 º outside the prescribed sectors.
(b) (i) All-round lights shall be so located as not to be obscured by masts,
topmasts or structures within angular sectors of more than 6 degrees,
except anchor lights prescribed in Rule 30, which need not be placed at an
impracticable height above the hull.

(ii) If it is impracticable to comply with paragraph (b)(i) of this section by

exhibiting only one all-round light, two all-round lights shall be used
suitably positioned or screened so that they appear, as far as practicable,
as one light at a distance of one mile.

10 Vertical sectors
(a) The vertical sectors of electric lights as fitted, with the exception of lights on
sailing vessels underway shall ensure that:
(i) at least the required minimum intensity is maintained at all angles from 5 º
above to 5 º below the horizontal;

(ii) at least 60 per cent of the required minimum intensity is maintained from
7.5 º above to 7.5 º below the horizontal.
(b) In the case of sailing vessels underway the vertical sectors of electric lights as
fitted shall ensure that:

(i) at least the required minimum intensity is maintained at all angles from 5 º
above to 5 º below the horizontal;

(ii) at least 50 per cent of the required minimum intensity is maintained from
25 º above to 25 º below the horizontal.

(c) In the case of lights other than electric these specifications shall be met as
closely as possible.
 100
11 Intensity of non-electric lights

Non-electric lights shall so far as practicable comply with the minimum intensities, as
specified in the table given in section 8 of this Annex.

12 Manoeuvring light

Notwithstanding the provisions of paragraph 2(f) of this Annex the manoeuvring light
described in Rule 34(b) shall be placed in the same fore and aft vertical plane as the
masthead light or lights and, where practicable, at a minimum height of 2 m vertically
above the forward masthead light, provided that it shall be carried not less than 2 m
vertically above or below the after masthead light. On a vessel where only one
masthead light is carried the manoeuvring light, if fitted, shall be carried where it can
best be seen, not less than 2 m vertically apart from the masthead light.

13 High-speed craft*
(a) The masthead light of high-speed craft may be placed at a height related to the
breadth of the craft lower than that prescribed in paragraph 2(a)(i) of this annex,
provided that the base angle of the isosceles triangles formed by the sidelights
and masthead light, when seen in end elevation, is not less than 27º.
(b) On high-speed craft of 50 m or more in length, the vertical separation between
foremast and mainmast light of 4.5 m required by paragraph 2(a)(ii) of this
annex may be modified provided that such distance shall not be less than the
value determined by the following formula:
(a + 17 )C
y= +2

where: y is the height of the mainmast light above the fore mast light in m;

a is the height of the foremast light above the water surface in service condition
in m;

ψ is the trim in service condition in degrees;

C is the horizontal separation of masthead lights in m.”

__________

*Refer to the International Code of Safety for High-Speed Craft, 1994 and the International Code
of Safety for High-Speed Craft, 2000.

14 Approval
The construction of lights and shapes and the installation of lights on board the vessel
shall be to the satisfaction of the appropriate authority of the State whose flag the
vessel is entitled to fly.
 101
Annex II
Additional Signals for Fishing Vessels Fishing in Close Proximity
1 General

The lights mentioned herein shall, if exhibited in pursuance of Rule 26(d), be placed
where they can best be seen. They shall be at least 0.9 m apart but at a lower level than
lights prescribed in Rule 26(b)(i) and (c)(i). The lights shall be visible all round the
horizon at a distance of at least 1 mile but at a lesser distance than the lights
prescribed by these Rules for fishing vessels.

2 Signals for trawlers

(a) Vessels of 20 m or more in length when engaged in trawling, whether using

demersal or pelagic gear, shall exhibit:

(i) when shooting their nets:

two white lights in a vertical line;
(ii) when hauling their nets:
one white light over one red light in a vertical line;
(iii) when the net has come fast upon an obstruction:
two red lights in a vertical line.
(b) Each vessel of 20 m or more in length engaged in pair trawling shall exhibit:
(i) by night, a searchlight directed forward and in the direction of the other
vessel of the pair;
(ii) when shooting or hauling their nets or when the nets have come fast upon
an obstruction, the lights prescribed in 2(a) above.

(c) A vessel of less than 20 m in length engaged in trawling, whether using

demersal or pelagic gear or engaged in pair trawling, may exhibit the lights
prescribed in paragraphs (a) or (b) of this section, as appropriate.
3 Signals for purse seiners

Vessels engaged in fishing with purse seine gear may exhibit two yellow lights in a
vertical line. These lights shall flash alternately every second and with equal light and
occultation duration. These lights may be exhibited only when the vessel is hampered
by its fishing gear.
 102
Annex III
Technical Details of Sound Signal Appliances

1 Whistles

(a) Frequencies and range of audibility

The fundamental frequency of the signal shall lie within the range 70-700Hz.
The range of audibility of the signal from a whistle shall be determined by those
frequencies, which may include the fundamental and/or one or more higher
frequencies, which lie within the range 180-700Hz (+/-1%) for a vessel of 20 m
or more in length, or 180-2100Hz (+/-1%) for a vessel of less than 20 m in
length and which provide the sound pressure levels specified in paragraph 1(c)
below.

(b) Limits of fundamental frequencies

To ensure a wide variety of whistle characteristics, the fundamental frequency of

a whistle shall be between the following limits:

(i) 70-200 Hz, for a vessel 200 m or more in length;

(ii) 130-350 Hz, for a vessel 75 m but less than 200 m in length;

(iii) 250-700 Hz, for a vessel less than 75 m in length.

(c) Sound signal intensity and range of audibility
A whistle fitted in a vessel shall provide, in the direction of maximum intensity of
the whistle and at a distance of 1 m from it, a sound pressure level in at least
one 1/3rd-octave band within the range of frequencies 180-700Hz (+/-1%) for a
vessel of 20 m or more in length, or 180-2100Hz (+/-1%) for a vessel of less
than 20 m in length, of not less than the appropriate figure given in the table
below.
 103

Length of vessel ⅓-octave band level at 1 m Audibility range in

in metres in dB referred to nautical miles
-5 2
2x10 N/m
200 or more 143 2
75 but less than 200 138 1.5
20 but less than 75 130 1
*1
120
*2
Less than 20 115 0.5
*3
111
*1
When the measured frequencies lie within the range 180-450Hz
*2
When the measured frequencies lie within the range 450-800Hz
*3
When the measure frequencies lie within the range 800-2100Hz

(d) Directional properties

The sound pressure level of a directional whistle shall be not more than 4 dB
below the prescribed sound pressure level on the axis at any direction in the
horizontal plane within ± 45 degrees of the axis. The sound pressure level at any
other direction in the horizontal plane shall be not more than 10 dB below the
prescribed sound pressure level on the axis, so that the range in any direction
will be at least half the range on the forward axis. The sound pressure level shall
be measured in that 1/3rd-octave band which determines the audibility range.

(e) Positioning of whistles

When a directional whistle is to be used as the only whistle on a vessel, it shall
be installed with its maximum intensity directed straight ahead.

A whistle shall be placed as high as practicable on a vessel, in order to reduce

interception of the emitted sound by obstructions and also to minimize hearing
damage risk to personnel. The sound pressure level of the vessel’s own signal at
listening posts shall not exceed 110 dB (A) and so far as practicable should not
exceed 100 dB (A).
 104
(f) Fitting of more than one whistle

If whistles are fitted at a distance apart of more than 100 m, it shall be so

arranged that they are not sounded simultaneously.

(g) Combined whistle systems

If due to the presence of obstructions the sound field of a single whistle or one
of the whistles referred to in paragraph 1(f) above is likely to have a zone of
greatly reduced signal level, it is recommended that a combined whistle system
be fitted so as to overcome this reduction. For the purposes of the Rules a
combined whistle system is to be regarded as a single whistle. The whistles of a
combined system shall be located at a distance apart of not more than 100 m
and arranged to be sounded simultaneously. The frequency of any one whistle
shall differ from those of the others by at least 10 Hz.

2 Bell or gong

(a) Intensity of signal

A bell or gong, or other device having similar sound characteristics shall

produce a sound pressure level of not less than 110 dB at a distance of 1 m
from it.

(b) Construction
Bells and gongs shall be made of corrosion-resistant material and designed to
give a clear tone. The diameter of the mouth of the bell shall be not less than
300 mm for vessels of 20 m or more in length. Where practicable, a power-
driven bell striker is recommended to ensure constant force but manual
operation shall be possible. The mass of the striker shall be not less than 3 per
cent of the mass of the bell.

3 Approval

The construction of sound signal appliances, their performance and their installation on
board the vessel shall be to the satisfaction of the appropriate authority of the State
whose flag the vessel is entitled to fly.
 105

Annex IV
Distress Signals

1. The following signals, used or exhibited either together or separately, indicate

distress and need of assistance:
(a) a gun or other explosive signal fired at intervals of about a minute;

(b) a continuous sounding with any fog-signalling apparatus;

(c) rockets or shells, throwing red stars fired one at a time at short intervals;

(d) a signal made by radiotelegraphy or by any other signalling method

consisting of the group ... – – – ... (SOS) in the Morse Code;

(e) a signal sent by radiotelephony consisting of the spoken word “Mayday”;

(f) the International Code Signal of distress indicated by N.C.;

(g) a signal consisting of a square flag having above or below it a ball or anything
resembling a ball;

(h) flames on the vessel (as from a burning tar barrel, oil barrel, etc.);
(i) a rocket parachute flare or a hand-flare showing a red light;

(j) a smoke signal giving off orange-coloured smoke;

(k) slowly and repeatedly raising and lowering arms outstretched to each side;

(l) *a distress alert by means of digital selective calling (DSC) transmitted on:
(i) VHF channel 70, or
(ii) MF/HF on the frequencies 2187.5 kHz, 8414.5 kHz, 4207.5 kHz, 6312
kHz, 12577 kHz or 16804.5 kHz;

(m) *a ship-to-shore distress alert transmitted by the ship’s Inmarsat or other

mobile satellite service provider ship earth station;

(n) signals transmitted by emergency position-indicating radio beacons;

(o) approved signals transmitted by radiocommunication systems, including

survival craft radar transponders.
2. The use or exhibition of any of the foregoing signals except for the purpose of
indicating distress and need of assistance and the use of other signals which may be
confused with any of the above signals is prohibited.
 106
3. Attention is drawn to the relevant sections of the International Code of Signals,
the International Aeronautical and Maritime Search and Rescue Manual, Volume
III and the following signals:
(a) a piece of orange-coloured canvas with either a black square and circle or
other appropriate symbol (for identification from the air);
(b) a dye marker.

th
*Ref: IMO Resolution A.1004 (25) adopted on 29 November 2007
___________________________________________________________

Abbreviation:
PDV Power-driven Vessel
NUC Not under command
VRAM Vessel restricted in her ability to manoeuvre
ROC Risk of collision
VCD Vessel constrained by her draught
NC Narrow Channel
TSS Traffic Separation Scheme
s/v sailing vessel
f/v fishing vessel
O/S Own Ship

Updated pages: - 13, 14, 23, 37, 40, 44,