In the interests of continued safe navigation practice the (IHO) and the (IMO) have jointly established a Global Navigational Hazard Warning System which is known as the World Wide Navigational Warning System.
The service is provided in the English language by radio and may be promulgated by Notice to Mariners where appropriate.
There are three types of warnings:
- Navarea warnings
- Coastal warnings and
- Local warnings
This covers the whole world which, for the purpose of distribution is divided into twenty one (21) geographical areas. The long range warnings are issued by an Area Co-ordinator on frequencies as listed in the ALRS volumes 3 and 5. NAVARAEA warnings are issued by Radio and Inmarsat transmissions, using EGC safety net. This is normally from 250 n miles from the coast outwards to the border of the Nav Area.
These are issued from the country of origin and affect a specific coastal region, in the area of hazard. These are transmitted on NAVTEX, VHF & MF radio transmissions. Usually this covers the area from the fairway or safe water mark of a port out to 250 n miles.
These may supplement coastal warnings and provide detailed information which often relates directly to inshore waters. As such they may not affect Ocean-going vessels to the same extent as vessels working inshore. The warnings often originate from Coastguards and Port control and may be transmitted in the National language only.
Details of Navigational warnings are contained in the following publications:-
- Admiralty List of Radio Signals, Vol.3(1) & 3(2) – NP 283(1) & NP 283(2)
- Admiralty List of Radio Signals, Vol.5 – NP 285
- Admiralty weekly Notices to mariners
- Admiralty summary of Annual Notices to Mariners
Information of Navigational significance can be obtained by:
- NAVTEX broadcasts
- EGC broadcasts on Satellite Communication Systems
- NBDP (Radio telex) broadcasts (not much used now)
- VHF/MF/HF Radio broadcasts
Publications that should be referenced against a received warning:
- Mariners Handbook (NP100)
- Sailing directions (Pilot books)
- Routeing charts (Monthly for each of five oceans)
- Navigational charts
- Admiralty tide tables
- Admiralty list of Lights and Fog Signals
- Ocean Passages for the World
What should I do on receipt of a communication?
- Read the text completely.
- Ascertain whether it covers or is likely to be encountered by your ship during the passage or your vessels trading areas.
- Plot positions as relevant.
- Make necessary corrections to the charts affected.
- Make entries in respective log.
- Sign the warnings and file them. (Maintain records).
- Inform Master, if it is significant to the current passage.
- Inform the relieving officer of same.
See also: MGN375 MSI