The Global Maritime Distress and Safety System (GMDSS) automates distress alerting and provides for improved safety communications at sea. Under GMDSS, search and rescue authorities and nearby ships will be rapidly alerted to a ship in distress through shore-based coordination. GMDSS also transmits maritime safety information. Ships are equipped according to the communication capabilities required for the area in which they operate, divided into Sea Areas 1 through 4 with varying coverage ranges. GMDSS aims to speed rescue responses and improve safety of ships and their crews over previous manual systems.

1. Global Maritime Distress
and Safety System
(GMDSS)

2. Basic Concept of the GMDSS
The fundamental difference between the old
and the new distress system is that the new
system is shore centred/coordinated and
moves emphasis from ship to ship alerting
to ship to shore alerting. The new system is
quicker, simpler and, most importantly, more
efficient and reliable than the old manual Morse
Code and radiotelephone alerting system.
GMDSS is specifically designed to automate a
ship’s radio distress alerting function, and
consequently, remove the requirement for
manual (human) watch-keeping on distress
channels.

3. The basic concept of the system is that search
and rescue authorities ashore, as well as
shipping in the immediate vicinity of the ship
in distress, will be rapidly and automatically
alerted to a distress situation so that they can
assist in a co-coordinated SAR operation with
minimum delay. The system also provides for
urgency and safety communications, and the
promulgation of maritime safety information
(MSI) including- navigational and
meteorological warnings and forecasts, and
other urgent safety information to ships. In
other words, every ship, fitted appropriately
for GMDSS, is able, irrespective of the area in
which it operates, to perform those
communication functions, which are essential
for the safety of the ship itself and of other
ships operating in the same area.

4. Before

5. Now

6. Now

7. The GMDSS Equipment

8. www.jojoeland.com

9. Functional requirements

The GMDSS regulations (chapter IV
of the International SOLAS
Convention), require that every
GMDSS equipped ship shall be
capable of;

10. 1. Distress alerting – Ship to shore
 EPIRB
 Digital Selective Calling (DSC)
 INMARSAT

11. 2. Distress alerting – Shore to ship

12. 3. Distress alerting – Ship to ship

13. 4. Search and Rescue Co-ordinating
Communications

14. 5. On-Scene Communication

15. 6. Locating

16. 7. Transmission/Reception of Maritime
Safety Information

17. 8. General Radiocommunications

18. 9. Bridge-to-Bridge Communications

19. Application
The GMDSS applies to vessels subject
to the SOLAS Convention - that is:
 Commercial vessels of 300 Gross
Registered Tons (GRT) and above,
engaged on international voyages.
 The GMDSS became mandatory
for such vessels
as at February 1, 1999.

20. 1 February 1992 – ships may comply with
the GMDSS requirements
1 August 1993 – ships must comply
with satellite EPIRB and NAVTEX
requirements
1 February 1995 – ships built on or
after this date must fully comply with
the GMDSS requirements
1 February 1999 – ships must
comply with the GMDSS
requirements

21. Equipment vs Operational
requirements

The major difference between the
GMDSS and its predecessor systems
is that the radio communications
equipment to be fitted to a
GMDSS ship is determined by the
ship's area of operation, rather
than by its size.

22. 




Because the various radio systems
used in the GMDSS have different
limitations with regards to range and
services provided, the new system
divides the world's oceans into 4
areas:
Sea Area 1
Sea Area 2
Sea Area 3
Sea Area 4

23. GMDSS Sea Area 1

This area of GMDSS is within the
radiotelephone coverage of at least
one VHF coast station in which
continuous DSC alerting is available.
Such area could extend typically 30
– 50 nautical miles from the coast
station.

25. GMDSS Sea Area 2

This area of GMDSS is an area
excluding sea area A1, within the
radiotelephone coverage of at least
one MF coast station in which
continuous DSC alerting is available.
Such area could extend typically
about 50 – 400 nautical miles from
the coast station

27. GMDSS Sea Area 3

This area of GMDSS is an area
excluding sea area A1 and A2, within
the radiotelephone coverage of at
least one HF coast station in which
continuous DSC alerting is available.
This area lies between about
latitudes 70º North and South.

29. GMDSS Sea Area 4

This area of GMDSS is an area
outside sea area A1, A2 and A3.