MARINE GUIDANCE NOTE

MGN 375 (M+F)

Navigation: Maritime Safety Information (MSI)

Notice to all Shipowners, Masters, Superintendents and Skippers of Fishing Vessels,
Yachts and Other Seagoing Craft

This notice replaces Marine Guidance Notes 23 and 44

PLEASE NOTE:-
Where this document provides guidance on the law it should not be regarded as definitive.
The way the law applies to any particular case can vary according to circumstances - for
example, from vessel to vessel and you should consider seeking independent legal advice if
you are unsure of your own legal position.

Summary
Maritime Safety Information (MSI) is defined in the Safety of Life at Sea (SOLAS) Convention,
Chapter IV as “navigational and meteorological warnings, meteorological forecasts and other
urgent safety related messages broadcast to ships.”

The Global Maritime Distress and Safety System (GMDSS) supports two independent
systems for broadcasting MSI:
• The International NAVTEX Service
• The International SafetyNET Service

The United Kingdom NAVTEX station coverage area is given in section 4.3 and is
complemented by VHF and MF radiotelephony.

This Notice gives guidance about the principal sources of relevant information. Masters,
skippers and others should refer to Maritime and Coastguard Agency (MCA/064) leaflet via
the MCA website at www.mcga.gov.uk for details, copies can also be obtained from MCA
offices.

Masters, skippers and others should use every available means to obtain the latest MSI.

1. Introduction/ Background
1.1 The Maritime and Coastguard Agency (MCA) is responsible in the UK for the broadcast
of Maritime Safety Information (MSI) on NAVTEX, VHF and MF and for the provision of
the Radio Medical Advice Link (MEDILINK) Service.

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1.2 To ensure that the user knows when to receive MSI for a given area and subject, many
MSI broadcasts are scheduled to a particular time, Land Earth Station (LES), and
satellite, in accordance with International Maritime Organization (IMO) guidance. For
example, all navigational warnings and meteorological forecasts are scheduled
broadcasts, while meteorological warning and distress alerts and certain urgent
navigational warnings are unscheduled broadcasts.

1.3 NAVTEX receivers should be programmed to receive information from the Radio
Stations covering the area in which the ship is navigating, or is about to enter, or
adjacent NAVTEX transmission sites. The Enhanced Group Calling Facility should be
logged on to the appropriate INMARSAT satellite for the international SafetyNET
Service broadcasting MSI to the area in which the ship is navigating, or is about to
enter; this may require monitoring broadcasts from separate satellites.

2. Navigational Warnings
2.1 Full use should be made of NAVTEX, INMARSAT’s Enhanced Group Calling Facility
(SafetyNET), HF, MF and VHF radio to obtain the most up-to-date Radio Navigational
Warnings.
2.2 Details of the UK COASTAL and NAVAREA elements of the Worldwide Navigational
Warnings Service are set out in the Admiralty List of Radio Signals and the Annual
Summary of Admiralty Notices to Mariners (Annual Notices to Mariners No. 13)
and in all good nautical almanacs.

2.3 A list of current Navarea One Warnings is published in Section III of Admiralty weekly
Notices to Mariners and also available on the UKHO website at www.ukho.gov.uk

3. Weather Information
3.1 Weather information for commercial shipping can be obtained at a number of UK ports
or direct from the Met Office by telephoning 0870 900 0100. Forecasts are also
available via the Met Office website at www.metoffice.gov.uk

3.2 At sea, full use should be made of weather information (including gale and storm
warnings and strong wind warnings for inshore waters) broadcast on NAVTEX,
INMARSAT’s Enhanced Group Calling Facility (SafetyNET), MF and VHF radio.

3.3 HM Coastguard (HMCG) Maritime Rescue Co-ordination Centres (MRCC) broadcast

weather information on Radio Telephony (RT) as follows:
• Sea Area (Shipping Forecast) – twice a day;
• Gale Warning – on receipt and every 3 hours;
• Strong Wind Warnings – on receipt becoming part of the next Inshore Forecast
• Inshore Forecasts up to 12 nautical miles offshore – new every 6 hours,
repeated after 3 hours;

3.4 Skippers of yachts, in particular, should listen to weather forecasts broadcast on local
and national radio, the repetition of meteorological information relayed by the
HMCG MRCC service, and refer to other sources which can be found in all good
nautical almanacs.

3.5 The definitions of visibility in nautical miles (nm) have been standardised and
based on the following:
• Very Poor: less than 0.5 nm
• Poor: 0.5 nm to 2 nm
• Moderate: 2 nm to 5 nm
• Good: greater than 5 nm

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4. NAVTEX
4.1 The coverage area of a NAVTEX station is a circle, radius 270 nautical miles from the
transmitter, whereas the service area is an area agreed between two adjacent stations
where their coverage areas overlap and a common boundary is formed.

4.2 Full details of these service and coverage areas can be found in Admiralty List of
Radio Signals Volumes 3 and 5. Masters should satisfy themselves that the Officer of
the Watch is aware of the need to inform them of the content of navigational and
meteorological warnings and weather forecasts.

4.3 NAVTEX COVERAGE AREAS (Refer to Annex 1 diagram)

Cullercoats S. North Sea, E. Coast of England and E.& N. Coasts of Scotland to

62°N.
Portpatrick N.W. Approaches to UK, W. Scotland, N. Channel, Irish Sea and St
George’s Channel and E. Coast of Ireland.
Niton S.W. Approaches N. of 48°27’N, English Channel, Celtic Sea and Dover
Strait.
Ostend S. North Sea and Dover Strait.

4.4 The 518 kHz NAVTEX service provides MSI and additional weather information as
follows:

ACTIVITY CULLERCOATS – NITON – PORTPATRICK -

518 kHz [G] 518 kHz [E] 518 kHz [O]

Gale Warnings on 0100, 0500, 0900, 0040, 0440, 0840, 0220, 0620, 1020,
receipt and at 1300, 1700, 2100 1240, 1640, 2040 1420, 1820, 2220
Shipping Forecast 0900, 2100 0840, 2040 0620, 1820
24 Hour Forecast &
24 Hour Outlook
Extended Outlook 0100 0040 0220
(3-5 days)
WZ Navigational 0100, 0500, 0900, 0040, 0440, 0840, 0220, 0620, 1020,
Warnings 1300, 1700, 2100 1240, 1640, 2040 1420, 1820, 2220
Tidal Surge Warnings On receipt On receipt On receipt
S. North Sea
SUBFACTS - 0440, 1640 0620, 1820
Navarea One 0500, 1700 0440, 1640 0220, 1420
Warnings

4.5 The National 490 kHz NAVTEX service also provides the Inshore Waters Forecast
(IWF) and Strong Wind Warnings on receipt. Weather Actual Reports are broadcast
once only at the next available broadcast schedule as indicated below.

ACTIVITY CULLERCOATS – NITON – PORTPATRICK -

490 kHz [U] 490 kHz [I] 490 kHz [C]

Inshore Forecast 0720, 1920 0520, 1720 0820, 2020

Weather Actual – 0320, 1120, 0120, 0920, 0020, 0420,
latest observations 1520, 2320 1320, 2120 1220, 1620

4.6 The broadcast of MSI may be interrupted or delayed as a result of Search and Rescue
operations. Any broadcast issues relating to NAVTEX should be addressed to the
nearest HMCG MRCC or the SAR Communications Manager on 01326 310800.

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4.7 Use of Abbreviations in NAVTEX Weather Broadcasts (Refer to Annex 2 table)

From 1 November 2006 a range of standard abbreviations were introduced to weather

forecasts broadcast on the international NAVTEX (518 kHz) service. This change has
been necessary to reduce the length of forecasts and overrunning.

More Information

Navigation Safety Branch

Maritime and Coastguard Agency
Bay 2/04
Spring Place
105 Commercial Road
Southampton
SO15 1EG

Tel : +44 (0) 23 8032 9316

Fax : +44 (0) 23 8032 9204
e-mail: navigationsafety@mcga.gov.uk

General Inquiries: infoline@mcga.gov.uk

MCA Website Address: www.mcga.gov.uk

File Ref: MNA 051/017/0004

Published: August 2008

Please note that all addresses and
telephone numbers are correct at time of publishing

© Crown Copyright 2008

Safer Lives, Safer Ships, Cleaner Seas

Printed on material containing minimum 75% post-consumer waste paper

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 Annex 1

(c) Crown Copyright 2008. All rights reserved.

Source: Admiralty List of Radio Signals Volume 5 (NP 285), page 269

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 Annex 2
COMMON ABBREVIATIONS FOR INTERNATIONAL NAVTEX SERVICE
NAVTEX Abbreviations Terminology in full
N North or Northerly
NE Northeast or Northeasterly
E East or Easterly
SE Southeast or Southeasterly
S South or Southerly
SW Southwest or Southwesterly
W West or Westerly
NW Northwest or Northwesterly

DECR Decreasing
INCR Increasing
VRB Variable
BECMG Becoming
LOC Locally
MOD Moderate
OCNL Occasionally
SCT Scattered
TEMPO Temporarily/Temporary
ISOL Isolated
FRQ Frequent/Frequency
SHWRS or SH Showers
C-FRONT or CFNT Cold Front
W-FRONT or WFNT Warm Front
O-FRONT or OFNT Occlusion Front
WKN Weakening
BLDG Building
FLN Filling
DPN Deepening
INTSF Intensifying/Intensify
IMPR Improving/Improve
STNR Stationary
QSTNR Quasi-Stationary
MVG or MOV Moving/Move
VEER Veering
BACK Backing
SLWY Slowly
QCKY Quickly
RPDY Rapidly
KT Knots
KMH Km/h
NM Nautical miles
M Metres
HPA HectoPascal
MET Meteo
FCST Forecast
TEND Further outlooks
VIS Visibility
SLGT or SLT Slight
QUAD Quadrant
POSS Possible
PROB Probability/Probable
SIG Significant
NC No change
NOSIG No significant change
FLW Following
NXT Next
HVY Heavy
SEV or SVR Severe
STRG Strong
FM From
EXP Expected
LAT/LONG Latitude/Longitude

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