QUESTIONS AND ANSWERS

OF PREVIOUSLY ASKED
TRICKY QUESTIONS BY
SURVEYORS
Nishit Kohli
 Q. Critical RPM?

◦ It is the RPM at which dynamic forces cause a machine component (shaft, rotor) to vibrate
at its natural frequency. Due to these vibrations a machine or its components get
damaged or may fail.
 Q. How many gnomonic charts are
there?

◦ There are 15 gnomonic charts covering the oceans of the world: North Atlantic, South
Atlantic, North Pacific, South Pacific and Indian Ocean.
 Q. Why is PL always perpendicular to
azimuth?

◦ Since, the zenith distance of the body is very large, the small arc of position circle will
appear as a straight line
Q. Which volume of ALRS lists out
the frequencies of a weather
facsimile recorder?
◦ ALRS Vol 3 Maritime Safety Information Services
 Q. Lights displayed by submarines
Submarines?

◦ may exhibit an amber flashing light in coastal waters, which is in addition to the
navigational lights of a power driven vessel. The amber flashing light is above the after
masthead light. The forward masthead light maybe lower than the sidelights
Q.How would you turn a vessel 'short
round' in a restricted channel, when
the ship is fitted with a right hand fixed
propeller and no bow thrust unit?
◦ Alter the ship's head to move to the port side of the channel, as this would gain the
greatest advantage when operating astern from transverse thrust, during the turn.
◦ (a) Dead slow ahead on engines and order the helm hard to starboard.
◦ (b) Stop engines, wheel midships.
◦ (c) Full astern, wheel amidships, until the vessel gathers sternway, then stop engines. The
effect of transverse thrust would generate a tendency for the bow to move to starboard
and the stern to move to port.
◦ (d) Wheel hard to starboard, engines full ahead to achieve the reverse heading.
Q. How will you predict wind speed
from a weather map?
◦ On a weather map, a geostrophic wind scale is provided, drawn to the scale of the
map. The distance between two consecutive isobars is taken off the weather map by a
divider. The divider is then placed on the geostrophic wind scale, both legs on the
horizontal line corresponding to the latitude in which the measurement is being made.
The left leg of the divider is placed on the margin and the position of the other leg
gives the geostrophic wind speed, interpolating as necessary between the curves. For
example, on the geostrophic wind scale illustrated, a distance between consecutive
isobars on the map equal to 1.65 cm (200 M) in 35° latitude will result in a geostrophic
wind speed of about 20 knots. Because of friction between the air and the earth's
surface, the surface wind speed over land would be about half the geostrophic wind
speed & over sea, about two-thirds.
 Q .What is the difference between
an isolated danger mark and
emergency wreck marking buoy?
◦ Isolated danger mark and emergency wreck marking buoy both indicate wrecks but the
emergency wreck buoy is used in the conditions where the new wreck is discovered and
stays in the position until it has been promulgated through notices in all charts and
publications whereas the isolated danger mark is present on the charts.
Radar Interference?
◦ SPOKING
◦ This is the name given to unwanted radial lines that sometimes appear on the screen.
These spokes may occur all round the screen or may be confined to certain arcs
only.The presence of faults such as dirty contacts either of the heading marker circuit
at the scanner or of the slip rings of the rotating deflection coils, are common causes of
spoking. Spoking can also be caused by heavy sparking of motors, etc., of other
instruments nearby, such as clear view screens, echo sounders, etc.
◦ STARRING
◦ Echoes sometimes appear on the screen in the form of curves or spirals of dotted lines,
which change position with every rotation of the scanner. This effect is called starring
and is caused by another ship's radar, whose transmitting frequency is within the
bandwidth of the own ship's radar, operating in the vicinity. If the other ship now puts
her set on stand-by, starring will disappear from own ship's radar screen.
◦ Black Moon: The 2nd new moon of a month.
◦ Blue Moon: The 2nd full moon of a month.
◦ Blood Moon: A 'blood moon' happens when the earth's moon is in a total lunar eclipse. The
view in the sky is striking as the usually whiteish moon becomes red or ruddy brown.
◦ Supermoon: A supermoon is a new moon or full moon that nearly coincides with the
perigee, i.e., the closest that the moon comes to the earth in its ecliptic orbit which results in
a slightly larger than the usual size of the apparent moon as viewed from the earth.
◦ Wet Moon: A wet moon is a visual phenomenon when the'horns' of the crescent moon
point up at an angle, away the horizon. A Wet moon occurs when the crescent moon is
low above the horizon and at a point more or less directly above the Sun's position below
the horizon.HORIZON
◦ Harvest Moon: The full moon which occurs at the autumnal equinox.
◦ Hunter's Moon: The following full moon after Harvest Moon is called Hunter's Moon.
What is the difference between an
ordinary light bulb and a
navigational light bulb?
◦ An ordinary light bulb can be fitted in 2 grooves with a spring lock arrangement and
has 1 filament.A navigational light bulb needs 3 grooves and has 2 filaments.
Q .Tidal Bore (also known as Bore
Tide)?
◦ A tidal bore is a strong tide that pushes up the river, against the current. In other words,
it is a situation where the flow of water from a river into the ocean reverses. A tidal bore
is a true tidal wave.Conditions for tidal bores to occur: 1. the river must be shallow2.
must have a narrow outlet to sea3.a broad funnel-shaped bay 4. the bay must also
have a large tidal range, typically morethan 6m between high and low
waterExamples: Hooghly river, India; Qiantang River, China(which has the world's
largest bore), etc.
◦ Grounding: Grounding occurs when a ship touches bottom accidentally. This act is not
intentional. It occurs generally through poor navigation and the lack of under keel
clearance. The severity of any damage incurred will depend on the speed of striking
and the nature of the ground that the vessel contacts.
◦ Beaching: It is the act of Intentionally grounding the damaged ship in order to save it
from foundering / sinking.
◦ Stranding: When a vessel has been grounded accidentally she is stranded. Stranding is
usually for a period of time. A vessel which has stranded may be in contact with the
ground at her bow, her stern, her mid-length, her entire length, or even along one side,
with the other side in deep water. Other shoals or rocks may exist close by, hampering
the refloating; currents and weather may be adverse and as a result of these elements
adverse weather may cause her to drive farther aground, and she may also be
damaged. As a result refloating may become an extremely complicated situation
Why is there a big difference
between HBW and VBW?
◦ Horizontal Beam Width → Between 0.6° and 2°Vertical Beam Width→ Between 15° and
30°HBW is less so that we can attain better bearing accuracy because if HBW was
large, targets close to each other would appear as a single target on the plan position
indicator(PPI). VBW is kept higher as the ships experience great rolling or pitching. As
per performance standards for navigational radar (IMO) the radar should function
without deterioration in performance when vessel is rolling or pitching up to +/- 10°.
When shall we not use Auto-Pilot?
1. In narrow channels
2. In or near areas of restricted visibility
3. In traffic areas when passing close to vessels
4. During pilotage and when manoeuvring at a slow speed.
5. During large course alteration
Why is amplitude the best method
for Compass error?

◦ As the altitude increases after sunrise the rate of increasing of Azimuth is very fast. This
can cause an error in observation and calculation. In azimuth calculation, GHA
increment value we use, is an assumed value which we interpolate from the
ALMANAC. In celestial navigation, we apply all the corrections to bring the body to the
Rational Horizon. However, in amplitude case the body itself is in the rational horizon.
Procedures for Reducing Ship Squat?
◦ The quickest and most effective way to reduce squat is to reduce the speed of the
ship. Remember, halving the speed will quarter the squat. Reduce the mean draught
of the vessel, if possible, by discharge of water ballast because the lower the draughts,
the block coefficient will be slightly lower in value.
◦ Move the vessel into deeper water depths. While in transit, ship should be kept moving
along the centerline of thenavigational channel. When in a river, if possible, avoid
interaction effects from nearby moored or moving ships or with adjacent riverbanks.
◦ A greater width of water will lead to less ship squat unless the vessel is outside her width
of influence.
Mirage
◦ A mirage is a naturally-occurring optical phenomenon in which light rays bend via
refraction to produce a displaced image of distant objects or the sky.
◦ A mirage of an astronomical object is a naturally occurring optical phenomenon in
which light rays are bent to produce distorted or multiple images of an astronomical
object. Mirages can be observed for such astronomical objects as the Sun, the Moon,
the planets, bright stars, and very bright comets. The most commonly observed are
sunset and sunrise mirages.
Corona
◦ In meteorology, a corona is an optical phenomenon produced by the diffraction of
sunlight or moonlight (or, occasionally, bright starlight or planet light) by individual small
water droplets and sometimes tiny ice crystals of a cloud or on a foggy glass surface.
◦ In its full form, a corona consists of several concentric, pastel-colored rings around the
celestial object and a central bright area which is often (especially in case of the
Moon) the only visible part of the corona and has the appearance of a bluish-white
disk which fades to reddish-brown towards the edge.
◦ The corona is the most pronounced when the size of the droplets is most uniform.
Coronae differ from halos in that the latter are formed by refraction (rather than
diffraction) from comparatively large rather than small ice crystals.
Theoretical Speed?

◦ Theoretical speed means that the propeller is 100% efficient and that there is no loss
due to drag, etc. This not possible in reality but is used as a reference for calculating
loss of efficiency.
Great Circle Sailing on a Mercator
Chart?
◦ We know, a Great Circle track can't be drawn on a Mercator Chart as the course will
keep on changing at every meridians. Therefore, longitudinal points (or waypoints) are
chosen along a Great Circle track laid on a Gnomonic chart and rhumb line courses
are drawn between them on a Mercator chart which approximates to a great circle
track closely.
◦ Plot the Great Circle course between the departure position and the arrival position on
a Gnomonic chart as a straight line.
◦ Positions are then taken off at convenient intervals of longitude supposedly 10°(it is up
to us, we can take 2° or 5° or any other amount as well as per our requirement)
◦ Transfer the positions on a Mercator chart. Join them by rhumb lines.
◦ Alternatively, in Great Circle Sailing we may also use Vertex and its formula to get the
intermediate points and plot them on a Mercator chart to do rhumb line courses
between them
Composite Circle Sailing?
◦ In some cases, the great circle track from one place to another may pass through very
high latitude which the navigator would like to avoid because of frontal depressions,
severe cold, fog, ice bergs, etc, associated with very high latitudes. In such cases, the
navigator decides on the maximum latitude (also known as limiting latitude or ceiling
latitude) of the passage and does a modified form of great circle sailing called
Composite Circle Sailing.
◦ To achieve this, two separate great circles are drawn, one from the departure position
and the other from the destination position, so that their vertices lie on the limiting
latitude. The ship sails along the first great circle till she reaches its vertex at the limiting
latitude, then along the limiting parallel of latitude along the arc of small circle) till she
reaches the vertex of the second great circle(also lying on the limiting latitude) and
thence to the destination position along the second great circle.
◦ The navigator then sails along the great circle track AV and, on reaching (celling
latitude), be sails along the parallel of latitude.
◦ On reaching W, he sails along the great circle track WB. The great circle tracks AV and
WE are arcs of two separate great circles. The leg VW is the arc of a parallel of latitude
and is hence not a great circle track. AVWB is hence called a composite track.
List of important Nautical
Publications?
◦ 1) NP1-NP72 → ADMIRALTY Sailing Directions (76 volumes)
◦ 2) NP74-NP88 → ADMIRALTY List of Lights and Fog Signals(15 volumes, from Vol A to Vol
Q, where I & O are omitted)
◦ 3) NP100 Mariner's Handbook
◦ 4) NP131 Catalogue of ADMIRALTY Charts and Publications
◦ 5) NP133A→ Paper Chart Maintenance Record
◦ 6) NP133C ADMIRALTY ENC and ECDIS Maintenance Record
◦ 7) NP136 → Ocean Passages for the World (2 volumes)
◦ 8) NP201-NP208 ADMIRALTY Tide Tables (8 volumes)
◦ 9) NP231 ADMIRALTY Guide to the Practical Use of ENCS
◦ 10) NP232 → ADMIRALTY Guide to ECDIS Implementation,Policy and Procedures.
◦ 11) NP234 Cumulative List of Notices to Mariners (2 parts)
◦ 12) NP247 → The Annual Summary of ADMIRALTY Notices to Mariners (2 parts)
◦ 13) NP281-NP286 ADMIRALTY List of Radio Signals (6 volumes)
◦ 14) NP294 → How to Keep Your ADMIRALTY Products Up-To-Date
◦ 15) NP314→ Nautical Almanac
◦ 16) NP323→ Star Finder and Identifier
◦ 17) NP350 → ADMIRALTY Distance Tables (3 volumes)
◦ 18) NP735 IALA Maritime Buoyage System
◦ 19) NP5011→ Symbols and Abbreviations Used on ADMIRALTY Paper Charts
◦ 20) NP5012 → ADMIRALTY Guide to ENC Symbols Used in ECDIS
Q. Why is 1 degree subtracted while
calculating the latitude from the
Polaris tables?
◦ 1 degree is subtracted while calculating the latitude from the Polaris tables to adjust for
the assumption which is taken in to account that
◦ Polaris lies on North Pole
◦ LATT.Alt of Polaris + a0 + a1 + a2-1°
◦ a0 is the correction to be applied to the T.Alt of Polaris to allow for the fact that it is not
exactly in line with the pole but circled around the pole with a very small polar
distance. It is obtained from the Nautical Almanac against the LHA Aries. An amount of
58.8' has been added to a0 at the time of computation to make it always positive.
◦ a1 is the second correction to Polaris. It is to allow for the fact the computations for a0 is
calculated using a reference latitude of 50°N. a1 is obtained from the Nautical
Almanac Polaris tables against the latitude. An amount of 0.6' has been added to the
value of a1 at the time of computation to make it positive.
◦ a2 is the third correction to allow for small seasonal changes in the SHA and declination
of Polaris from the computed. It is obtained from the Nautical Almanac Polaris tables
against the month of the observation. An amount of 0.6' has been added to the value
of a2 at the time of computation to make it always positive.
◦ Thus we can see that amounts of 58.8' +0.6' +0.6' = 1° has been added at the time
computation and therefore, has to be subtracted while calculating.
◦ Isogonic lines are those lines on the earth's surface joining all places along which
variation(also known as magnetic declination) is the same.
◦ Agonic lines are those lines on the earth's surface joining all places along which the
variation(also known as magnetic declination) is zero.
◦ Isopleths are lines on a weather map joining all places having the same value of a
particular meteorological feature(temperature, dew point, rainfall, wave-heights, etc.)
◦ An isobar is a line drawn, on a weather map, joining all places having the same
atmospheric pressure at the time for which that weather map was drawn.
Clearing Bearing

◦ A conspicuous object is selected and a bearing leading clear of danger is laid off from
it. A vessel kept on this bearing will pass clear of the nearby hazard/danger.
Difference between Lee tide and
Weather tide

◦ Lee tide: Tidal stream flowing in the same direction as the wind.
◦ Weather tide: Tidal stream flowing in the opposite direction to the wind.
Spoil Ground Mark (or Buoy)

◦ Spoil Ground Mark (or Buoy) A mark or buoy indicating an area used for deposition of
waste material.
◦ An area of sea bottom reserved for the dumping of waste of one kind or another.
Usually clear of any likely anchorage, and in relatively deep water. Marked on the
chart by a surrounding dashed line, and at sea(if at all) by yellow buoys.
Why is the salinity of Red Sea very
high?
◦ There is a lack of river or streams draining into the sea,therefore a very little or no fresh
water inflow. The location of the Red Sea is in a warm region of dry weather, therefore
there is a high rate of evaporation and very little precipitation.
◦ Northern end of Red Sea → Salinity = 41%
◦ Southern end of Red Sea → Salinity =36%
Additional Measures to Prevent
Anchor Dragging in Bad Weather?

◦ Reduce wind area of the vessel

◦ Use ballast to increase the draft of the vessel
◦ Reduce trim by stern as much as possible Trim by head and increase it if possible. This is
to move the wind center backward and the hydrodynamic center forward to reduce
the deviation of the vessel and improve the vessel's stability
Why does TRS recurve?
◦ We know that the angular velocity of earth is different in different latitude which is
maximum at the equator and zero at the poles. Due to this the balance of angular
momentum between TRS and earth's rotation changes. Since, the angular momentum
of earth reduces in higher latitude, TRS increases its angular velocity to preserve the
momentum, causing it to move easterly. Hence, we can say that TRS changes it
direction to east for the preservation of angular momentum.
◦ TRS as a three step process:
◦ 1. Moves west due to trade winds.
◦ 2. Moves towards the pole due togyroscopic precession caused by the forces of rising
warm wind at the eye.
◦ 3. Changes the direction to east for the preservation of angular momentum
No Go Areas?
◦ Coastal and estuarial charts should be examined, and all areas where the ship
CANNOT go must be carefully shown by highlighting or cross hatching, care being
taken to not obliterate information such as a navigation mark or a conspicuous object.
◦ Areas so marked are to be considered as no-go areas. In waters where the tidal range
may not be very large, no-go areas will include all charted depths of less than the ship's
draught plus a safety margin.
◦ Such areas will vary according to the ship's draught so will not necessarily be the same
for both inward and outward passages.
◦ In general the line determining "no-go" will be not less than draught + 10%, though this
will need to be modified according to the prevailing circumstances.
◦ Draught + 10% may well prove adequate in areas where the sea is smooth but will
require a considerably higher figure if the ship is liable to pitch, roll or squat.In confined
waters, where the tidal height may have a large influence, such no-go areas will vary
according to the time of passage.
◦ Initially all areas and dangers showing charted depths of less than the draught plus the
safety margin should be considered no-go, though such no go areas may be
subsequently amended when the actual time of passage is known.
◦ Such areas will need to be carefully marked showing the times and state of tide at
which they are safe.
Conditions when we have to make a
new Deviation Card
◦ 1. On a new vessel.
◦ 2. After periods of lay up (drydocking)
◦ 3. When a new compass is installed.
◦ 4. When deviation exceeds 5" on any heading.
◦ 5. After trauma such as lightening strike, grounding fire, etc.
◦ 6. When the compass performance is unsatisfactory or unreliable
◦ 7. When a record of compass deviation has not been maintained.
◦ 8. After alterations and additions to vessel's structure and equipment.
◦ 9. Every 2 years.
How will you know that the azimuth
bearing circle of the compass is
correct?
◦ By taking a bearing of a terrestrial object, supposedly a lighthouse, with the arrow
indicator uppermost. Then take a second bearing of the same object with the arrow in
the downward position. Both the readings should be the same and the bearing circle
can be used with confidence.
Which radar will be more reliable in
heavy weather?

◦ S-Band Radar will be more reliable in heavy weather because attenuation is

comparatively less than the x-band radar as the echoes of s-band radar are
comparatively longer in wavelength and hence, the picture obtained by the S-band
radar is less affected by sea-clutter and rain-clutter.
Berthing Situation:-
◦ Vessel heading 060°
◦ Current from port quarter
◦ Jetty at the North
◦ You have one tug
◦ Which side will you berth and where will you make fast the tug?
◦ Vessel will berth to her stbd side.
◦ Vessel will make fast the tug to her port bow because she already has the engines and
rudder to control her stern.
◦ Alternative solutionVessel has to turn around by letting go port anchor and with a single
tug pulling from the stbd quarter.
◦ Once the vessel has finished turning, tug shall be released and made fast to port
midship.Vessel will go alongside by falling back with the tide, slacking the port chain
and laterally pushed by the tug.
◦ She will go stbd side alongside with the tug at her port midship.
◦ For casting off, there will be one tug at her port quarter to pull the stern away and bow
will align with the channel by heaving up her port anchor.
What are the outer and inner circles
of a Compass Rose?
◦ Every navigational chart has at least one compass rose overprinted on it and most
have three or four.
◦ Printed in magenta, most roses have 2 concentric rings.
◦ The outer one shows True directions and the inner one shows Magnetic directions.
◦ The outer one is graduated in degrees whereas the inner one is graduated in points of
11.25 degrees.
How will you not get confused
between Jupiter and Venus?
◦ In the Nautical Almanac (NP-314), there is a page (page no. 8), just before daily pages
which says "PLANET NOTES".
◦ In this page visibility of 5 planets (Venus, Mars, Jupiter, Saturn, Mercury) is described and
we can et information from here about the planets and when they will be visible for
observation(in which months and whether visible in the morning sky or in the evening
sky).
◦ Additionally, at the bottom of this same page, there is a small section, "DO NOT
CONFUSE" which advises the user to not get confused when 2 planets are visible at the
same time, by indicating which planet will be brighter than the other at such situations.
What is the polling feature in LRIT?

◦ This is a special service in which an operational center sends polling or control

commands to a selected SES, group of SES or many SES on a sea area to perform
desired functions In simpler words, it is a feature that allows administrations to seek
information about ship'sposition from ship's LRIT.
ARTICLES OF ROR
◦ There are 9 articles of ROR found in the starting pages of IMO ROR book.
◦ i. General obligations
◦ ii. Signature, ratification, acceptance, approval and accession
◦ iii. Territorial application
◦ iv. Entry into force Revision Conference
◦ V. Revision conference
◦ vi. Amendments to the regulations
◦ vii. Denunciation
◦ viii. Deposit and Registration
◦ ix. Languages
Company UKC Policy
..\UKC and OHC policy.pdf
WHAT IS THE USE OF WET AND-DRY-
BULB HYGROMETER?
◦ The wet-and-dry-bulb hygrometer is an instrument for obtaining the relative humidity
and/or dew point temperature of air.
PDV 3 pts in stbd bow and can see
sidelights and masthead lights in
line?
◦ It's a crossing situation, with both sidelights visible the aspect is zero so she will pass clear
of stern , therefore i will maintain my course and speed.
How will you confirm it is head on or
not
◦ The other vessel should be within 3°-5° of own ship heading as 3° is the cut off sector of
the lights and 2° is allowance for yawing.
Crossing vsl coming from abaft the
beam:
◦ Determination of vessel overtaking or not, By vessel overtaking-
◦ By night: at first she would be able to see her Sternlight followed by sidelights then we are
overtaking.
◦ By Day- Using radar plotting or AIS (with Radar in-operational) find out the course of the
other vessel and then find out the aspect of the other vessel, if the aspect of other vessel is
more than 112.5° and reducing we are overtaking. Action- Keep clear of the vessel
overtaking.
◦ In doubt- Consider yourself to be overtaking and keep clear of the other vessel as per Rule
13 (c). By vessel being overtaken- Determine the aspect by the use of Radar plotting or by
checking the course of other vessel from AIS if the aspect is less than 22.5° and increasing or
just take a bearing if it is more than 22.5° abaft the beam and decreasing then the other
vessel is overtaking.
◦ Action- 1. Maintain course and speed. 2. If the overtaking vessel is not taking action then
sound 5 or more rapid short blasts. 3. If still not taking action or in doubt give a bold
alteration to port and pass stern of the overtaking vessel
RV without radar hearing fog signal 3
pts on stbd bow?
◦ 1. Post extra lookout forward.2. Determine ROC with fog signal intensity of other
vessel.3. If increasing the reduce speed or take all way off as per rule 19 (e).
RV without radar fog signal port qtr n
increasing intensity?
◦ Intensity increasing which means ROC exists, post extra lookout aft, alter course to stbd
by 60° and take the signal on stbd quarter proceed in same way until danger of
collision is over.
Explain rule 8 f?
◦ 8 (f) (i): It says that a vessel which is not required to impede the passage as mentioned
in rule 9, 10 and 18 should take action before ROC exists to allow sufficient sea room for
the passage of vessel of which the passage is not to be impeded.8 (f) (ii): It says that a
vessel not required to impede the passage will still be required to take action if ROC
has developed, suppose a CBD has a PDV on her stbd, by rule 15 if ROC develops it is
the responsibility of CBD to keep clear as she has the other vessel on her stbd, however
as per this section the PDV is still required to keep out in case of ROC.8 (f) (iii): It says
that a vessel passage of which is not to be impeded shall comply with normal ROR,
which means that in a CBD PDV situation she shall comply with Rule 15 if ROC develops
and keep clear of the PDV, and the best she could do here is reduce speed.
Own v/l CBD power driven v/l
crossing from port side action?
◦ 1. Take bearings and determine ROC, PDV should take action as per 8 (f) (i) before
ROC exists.2. If yes the maintain course and speed, as per rule 15 PDV should keep
clear.3. If still not taking action, sound 5 or more rapid short blasts.4. If still no action then
reduce speed and let her pass ahead.
NUC v/l overtaking own v/f from stbd
quarter action?
◦ If ROC exists as per rule 13 (a) it’s NUC responsibility to keep clear but as I know that
NUC vessel cannot take action so I will take a round turn to port and pass stern of the
other vessel, action would be as per rule 17 (a) (ii).
Own v/l seas other v/l on stbd bow
masthead light and both side lights
visible action?
◦ Determine if it is a head on situation or crossing situation. If it’s a head on situation then
alter to stbd pass port to port, if It’s a crossing situation, with both sidelights visible the
aspect is zero so she will pass clear of my stern, therefore i will maintain my course and
speed.
Sound signal in narrow channel
sound signal
◦ When overtaking- two prolonged one short: I intend to overtake you from stbdTwo
prolonged two short: I intend to overtake you from portOne prolonged one short one
prolonged one short: If the vessel being overtaken is in agreement.When nearing a
bend: One prolonged blast, any vessel in the vicinity to reply with one prolonged blast.
Signs of approaching TRS?
◦ 1. Swells travelling radially outwards2. Falling Pressure3. Visibility exceptional4. Dark
clouds on the horizon with thundering5. Peculiar red copper colour of sky during
evening6. Cirrus clouds leading towards the centre7. Increasing wind speed8. Storm
warnings
How to locate the centre of TRS?
◦ Using buys ballots law. Face true wind area of low pressure will be 8-12 points on your
right in NH and to left in SH. 12 points in drop in pressure is 5 mb and 8 points if drop in
pressure is 20 mb
How will u determine in which
semicircle you are in NH?
◦ In RHSC wind will be veering and in LHSC wind will be backing.
Why dangerous quadrant is so
called.
◦ There are 3 reasons.1. The TRS is expected to recurve towards that direction.2. The
winds in dangerous quadrant are such that they push the vessel in the direct path of
the storm.3. The wave heights encountered in this quadrant are greatest.
Avoiding action in TRS?
◦ 1. Take bearing of storm centre using Buys Ballots Law. Face the true wind and storm
centre will be 8-12 points on the right. If pressure has fallen 5 mb below normal after
allowing for semi diurnal variation take 12 points, if it is 20 mb below normal allow 8
points as the TRS is in near vicinity.2. Determine which semicircle you are in. Wind will
veer in RHSC and back in LHSC. Due care must be exercised while determining wind
direction.3. Once the position is confirmed, take action- In Dangerous semicircle i.e.
RHSC: keeping the wind on stbd bow 1 point for slow vessels (speed less than 12 knots)
and 4 points for vessel fast vessels (speed more than 12 knots) altering as the wind is
Veering.- In Navigable semicircle i.e. LHSC keeping the wind 4 points on Stbd quarter,
alter course as the wind is Backing.In both the above cases vessel to proceed in the
same way until the pressure comes back to normal.
◦ 1. Take bearing of storm centre using Buys Ballots Law. Face the true wind and storm
centre will be 8-12 points on the left. If pressure has fallen 5 mb below normal after
allowing for semi diurnal variation take 12 points, if it is 20 mb below normal allow 8
points as the TRS is in near vicinity.2. Determine which semicircle you are in. Wind will
veer in RHSC and back in LHSC. Due care must be exercised while determining wind
direction.3. Once the position is confirmed, take action- In Dangerous semicircle i.e.
LHSC: keeping the wind on port bow 1 point for slow vessels (speed less than 12 knots)
and 4 points for vessel fast vessels (speed more than 12 knots) altering as the wind is
Backing- In Navigable semicircle i.e. RHSC keeping the wind 4 points on Port quarter,
alter course as the wind is veering.In both the above cases vessel to proceed in the
same way until the pressure comes back to normal.
Shadow sectors
◦ Shipboard structures such as masts, Samson posts etc., obstruct the radar beam partly
Targets directly beyond the obstruction do appear on the PPI because of diffraction,
but their detection ranges are considerably reduced. Such areas are known as shadow
sectors. The presence of shadow sectors can be found out by reducing the gain
control till such time that the clutter echoes are only just visible. The total absence of
clutter echoes in the direction of the obstruction indicates its presence. The relative
bearings of the extremities of the shadow sector are measured and displayed. If the
gain is increased elutter will appear in the shadow sectors.
Blind Sector
◦ Sometimes, the shipboard structures, such as a funnel, completely obstructs the radar
beam. Due to this, no echoes are received from targets beyond these structures and
so they are not detected at all. Such targets are said to be in the 'Blind Sector' of the
scanner. This is caused due to bad siting of the scanner. In modern ships, the scanner is
usually mounted on a special mast, so that it is above or far away from all major
obstructions and hence has no Blind Sectors.
◦ Blind sectors can also be measured as no clutter echoes ever appear within it.
Why necessary 2 stop engines in safe
speed?
◦ Safe speed will reduce the stopping distance which is required for the situation, so
basically safe speed is maintained for ensuing that the vessel can stop in time which is
suitable for the prevailing circumstance, and in all cases where danger is imminent or
can’t be avoided vessel should be stopped
Radar not operational, you hear fog
signals apparently four points on port
bow, action?
◦ 1. Post extra lookout forward.2. Shift sound signal from aft to forward3. Determine ROC
with fog signal intensity of other vessel.4. If increasing the reduce speed or take all way
off as per rule 19 (e).
Fog signal abeam increasing
intensity action
◦ With fog signal abeam, reduce speed will be the best action. With vessel right ahead in
R.V overtake her from her port side, if ROC exists then reduce speed.
Fog signal stbd quarter action (bold
alteration)
◦ Bold alteration to port and take the vessel on port quarter
How to calculate wind speed by
isobars?
◦ With the help of geostrophic wind scale provided, with the divider we can measure the
distance between two isobars and take it to the geostrophic wind scale against the
latitude which will give me wind speed.
Target above 3nm and announce vsl NUC, action based on which rule , if u
alter course to stbd then how much degree and why not u alter to port, i
explain him i will alter to stbd and will not alter to port , big discussion with him on
this situation. (he put a remark on this on my sheet).?

◦ Action: with vessel NUC, as per rule 18 (a) it is my responsibility to keep clear, I can alter
to port here simply because the other vessel is not a PDV and rule 15, 17 (c) is not
applicable in this case.
Can position circle be drawn for
celestial body, if yes, which all
conditions
◦ In cases where the body is close to observer i.e. in high latitude observations, with lat
and declination same name and close to each other.
it takes around 15 minutes for the eyes of an average
person to get adjusted to low lights from artificial lights.

◦ 5min for cones to adapt, 10 min for rods to adapt... roughly 15 min to adapt
How to Plot great circle route in
ecdis??
◦ First we make our normal Rumb line courses from birth to birth. After that from , we will
open the Passage plan editor option in the ECDIS and in there we will select those two
waypoints between which we want GC course and then click on convert to GC
course there will it will be done click Save and then exit the Passage plan Editor and
activate the route. you gc passage plan is ready to use.
Blind Pilotage:-
◦ Blind pilotage means the navigation of the ship through restricted waters in low visibility
with little or no recourse to the visual observation of objects outside the ship. The
principle non-visual aid to navigation is the ship's radar. Other non-visual aids are also
employed e.g. AIS, echo sounder, ROTI. The organization to achieve this is called the
blind pilotage organization, comprising a BP team, led by a BP Officer (BPO).
◦ Factors to consider: Degree of risk involved in restricted waters must be carefully
assessed prior entering doubled up & watch level upgraded. Congestion due to other
shipping Bridge watchesshould be considered. Both radars/ ARPA should be
operational.
◦ Consequences of failure of radar or other vital aids should be considered & risk
assessment should be done.• Availability of navigational aids, which can be used in
restricted visibility, must be taken into account, Racons, AIS buoys / stations, VTS etc.•
Parallel indexing can be used as a powerful tool for position monitoring & execution of
passage. • Draw one set of parallel index lines ahead of those in use.• Plan the
passage so as to Steer a course to pass a given distance off a radar conspicuous
navigational mark or point of land.• Use clearing & wheel over ranges.Use the ROTI to
plan alteration of courses, mark wheel over points & wheel over lines at alterations.• Do
not clutter the radar display. Remove the indexing lines as soon as they are finished
with • Identify radar contacts as soon as possible.• Fix the position at frequent intervals•
Fix immediately after any alteration of course.• Maintain a steady, unhurried precise
flow of information to the master.• Check what lights and sound signals are expected
on the passage & keep a lookout for them. • Echo sounder is also a valuable aid in
restricted visibility in coastal waters. Check what depths are expected on the passage
and compare with echo sounder readings. • If in doubt, immediately inform the master
Sole lookout as per stcw
◦ In open sea condition or when well away from danger during daytimeOow looking all
navigation. The situation has been carefully established without doubt that it is safe to
operate with sole lookout.full around has been taken. all relevant factors, including but
not limited to:
◦ state of weather VisibilityTraffic density Pproximity of danger to navigation.
Gyro fails, what happen to radar
/arpa ?
◦ Radar goes on head up modeVessel will deplete from coCourse recorder will show zig
zig pathAlarm
Phasing signal in navtex?
◦ To bring the navtex from standby to On condition.. phasing signal is used just before
transmission ......zczc indicates phasing period is over
Correction is VSA?
◦ Mhws : given in chart but tide maybe low so we have to apply correction
How will you find wind and current?
◦ Routin chart, ecdis, anemometer, ocean passage of the word
No gyro, can ship sail?
◦ No, cannot sail as per SOLAS 5 reg.19 2.2.5
Anchor holding
◦ Stw: Sow (cog) - positive speedSog: Sog(gps) - No speedAnchor draggingSow: No
speedSog: negative speed
PDV 3 pts in stbd bow and can see
sidelights and masthead lights in line?

◦ It's a crossing situation, with both sidelights visible the aspect is

zero so she will pass clear of stern , therefore i will maintain my
course and speed.
How will you confirm it is head on or
not

◦ The other vessel should be within 3°-5° of own ship heading as 3°

is the cut off sector of the lights and 2° is allowance for yawing.
Crossing vsl coming from abaft the
beam:
◦ Determination of vessel overtaking or not, By vessel overtaking- By night: at first she
would be able to see her Sternlight followed by sidelights then we are overtaking. By
Day- Using radar plotting or AIS (with Radar in-operational) find out the course of the
other vessel and then find out the aspect of the other vessel, if the aspect of other
vessel is more than 112.5° and reducing we are overtaking. Action- Keep clear of the
vessel overtaking. In doubt- Consider yourself to be overtaking and keep clear of the
other vessel as per Rule 13 (c). By vessel being overtaken- Determine the aspect by the
use of Radar plotting or by checking the course of other vessel from AIS if the aspect is
less than 22.5° and increasing or just take a bearing if it is more than 22.5° abaft the
beam and decreasing then the other vessel is overtaking. Action- 1. Maintain course
and speed. 2. If the overtaking vessel is not taking action then sound 5 or more rapid
short blasts. 3. If still not taking action or in doubt give a bold alteration to port and pass
stern of the overtaking vessel.
RV without radar hearing fog signal 3
pts on stbd bow?
◦ Ans. 1. Post extra lookout forward.
◦ 2. Determine ROC with fog signal intensity of other vessel.
◦ 3. If increasing the reduce speed or take all way off as per rule 19 (e).
RV without radar fog signal port qtr n
increasing intensity?
◦ RV without radar fog signal port qtr n increasing intensity?Ans. Intensity increasing
which means ROC exists, post extra lookout aft, alter course to stbd by 60° and take the
signal on stbd quarter proceed in same way until danger of collision is over.
Q Explain rule 8 f?
◦ 8 (f) (i): It says that a vessel which is not required to impede the passage as mentioned
in rule 9, 10 and 18 should take action before ROC exists to allow sufficient sea room for
the passage of vessel of which the passage is not to be impeded.
◦ 8 (f) (ii): It says that a vessel not required to impede the passage will still be required to
take action if ROC has developed, suppose a CBD has a PDV on her stbd, by rule 15 if
ROC develops it is the responsibility of CBD to keep clear as she has the other vessel on
her stbd, however as per this section the PDV is still required to keep out in case of ROC.
◦ 8 (f) (iii): It says that a vessel passage of which is not to be impeded shall comply with
normal ROR, which means that in a CBD PDV situation she shall comply with Rule 15 if
ROC develops and keep clear of the PDV, and the best she could do here is reduce
speed.
Own v/l CBD power driven v/l
crossing from port side action?
◦ Ans. 1. Take bearings and determine ROC, PDV should take action as per 8 (f) (i) before
ROC exists
◦ .2. If yes the maintain course and speed, as per rule 15 PDV should keep clear.
◦ 3. If still not taking action, sound 5 or more rapid short blasts.
◦ 4. If still no action then reduce speed and let her pass ahead.
NUC v/l overtaking own v/f from stbd
quarter action?
◦ Ans. If ROC exists as per rule 13 (a) it’s NUC responsibility to keep clear but as I
know that NUC vessel cannot take action so I will take a round turn to port and
pass stern of the other vessel, action would be as per rule 17 (a) (ii).
Own v/l seas other v/l on stbd bow masthead
light and both side lights visible action?

◦ Ans. Determine if it is a head on situation or crossing situation. If it’s a head on

situation then alter to stbd pass port to port, if It’s a crossing situation, with both
sidelights visible the aspect is zero so she will pass clear of my stern, therefore i
will maintain my course and speed.
Why necessary 2 stop engines in safe
speed?
◦ Ans. Safe speed will reduce the stopping distance which is required for the
situation, so basically safe speed is maintained for ensuing that the vessel can
stop in time which is suitable for the prevailing circumstance, and in all cases
where danger is imminent or can’t be avoided vessel should be stopped
Radar not operational, you hear fog signals
apparently four points on port bow, action?
◦ Ans. 1. Post extra lookout forward.
◦ 2. Shift sound signal from aft to forward
◦ 3. Determine ROC with fog signal intensity of other vessel.
◦ 4. If increasing the reduce speed or take all way off as per rule 19 (e).
Target above 3nm and announce vsl NUC, action based on which rule , if u
alter course to stbd then how much degree and why not u alter to port, i
explain him i will alter to stbd and will not alter to port , big discussion with him on
this situation. (he put a remark on this on my sheet).?

◦ Action: with vessel NUC, as per rule 18 (a) it is my responsibility to

keep clear, I can alter to port here simply because the other
vessel is not a PDV and rule 15, 17 (c) is not applicable in this
case.
MOB in tss
◦ Actions are to be taken in the following sequence:
◦ Release the MOB Marker on the same side (lifebuoy with light and smoke signal)
◦ Hard over Rudder to the side of MOB Press MOB button in GPS & ECDIS
◦ Inform Master (usually Master will be on the bridge when vessel is in TSS)
◦ Post extra lookouts and guide them to identify the person/MOB marker
◦ Sound 'O' on ships whistle (3 Prolonged blast) & hail "MAN OVERBOARD"Raise flag "Oscar“
◦ Inform VTS / Port Authority
◦ Inform Engine Room & Anchor party
◦ DO NOT PERFORM RECOVERY TURN IN TSS, ONLY TO BE DONE WHEN AUTHORISED BY TSS.
◦ Broadcast URGENCY message in VHF ( Later can be upgraded to DISTRESS if unable to start
rescue immediately)
◦ Manoeuvre the vessel to ITZ or Separation zone for Anchoring
◦ Press VDR Backup button (if appropriate)
◦ Maintain watch on VHF CH16 (or Designated by VTS / SAR Authority)
 GPS failure
◦ Inform Master.
◦ Switch over to GPS 2 (If fitted & working).
◦ Note down the last position obtained from GPS.
◦ Obtain the position of the vessel from Celestial or Terrestrial means.
◦ Increase the frequency of position fixing.
◦ Plot the position of the vessel in ECDIS.
◦ Inform VTS / Port Authority & Company Agent.
◦ Monitor the position of vessels in vicinity.
◦ Navigate the ship clear from any proximity to navigational hazard.
◦ Try to rectify the GPS by referring the GPS Manufacturers Manual.
◦ Keep a record of all events.
◦ Effect of GPS Failure: ECDIS gives mandatory alarm & automatically switches over to DR mode.
Radar and ARPA switches to Relative motion.
◦ There are chances that Gyro may give an alarm, Since Gyro has latitude error and which
needs GPS Sensor to correct the same.
◦ AIS will not transmit position of the vessel
GYRO failure
◦ Inform Master.
◦ Note down Date, Time & Position.
◦ Inform VTS / Port Authority.
◦ Switch over to the Backup Gyro feed (if fitted).
◦ Switch over Autopilot to Hand Steering.
◦ Steer the vessel with Magnetic Compass.
◦ Obtain Magnetic Compass Error by celestial or Terrestrial means.
◦ Plot the position of the vessel frequently.
◦ Monitor the position of the vessels in vicinity.
◦ Try to troubleshoot the Gyro with reference to the manual, if unable to rectify inform the
same to company agent.
◦ Keep a record of all events.
◦ Effects of GYRO Failure: RADAR will automatically switch to HeadUp mode & Relative motion
◦ ECDIS will give Alarm and will change the input to GPS – COG
◦ AIS will transmit "DATA NOT AVAILABLE" in heading of the vessel
Radar fail
◦ Single RADAR Failure (X Band or S Band) :
◦ Inform Master.
◦ Firstly, Navigate the vessel safely with the other RADAR(If fitted).
◦ Reduce speed if appropriate.
◦ Try to identify the cause for RADAR Failure by Troubleshooting as per Manufacturer Manual.
◦ Inform VTS / Port Authority & Company Agent.
◦ Keep a record of all events.
◦ Both RADAR Failure (X Band & S Band) :
◦ Inform Master.
◦ Reduce Speed of the vessel.
◦ Post extra lookouts.
◦ Do manual plotting by obtaining Bearing and Range of the target vessels from AIS.
◦ Monitor the position of the vessels in vicinity.
◦ Monitor the proximity to any danger to Navigation.
◦ Inform VTS / Port Authority & Company agent.
◦ DO NOT SWITCH ON NUC LIGHTS / SHAPES
◦ Pass at a safe distance from all Navigational Hazards by using PI (Parallel Indexing) in ECDIS.
◦ Broadcast SAFETY Message in VHF CH70(Alert) & CH 16.