The Global Maritime Distress and Safety System (GMDSS) is an international
system with world-wide availability to ensure rapid, automated alerting
of shore-based stations and rescue authorities, in addition to ships in the
immediate vicinity, so that they can assist in a coordinated search and rescue
operation with the minimum of delay in the event of a marine distress.
Another important feature of GMDSS is the reliable dissemination of maritime
Technically, the GMDSS system is built up with different complementary
communication components, including advanced terrestrial radio stations
and satellite systems.
GMDSS was introduced by the
International Maritime Organization in 1992 and obtained
full operability in 1999.
It replaces the previous ship-to-ship safety system, which relied
on a manual Morse Code system and voice radio telephony on
VHF Channel 16 and MF 2182 kHz.
Today, the GMDSS system offers an automated ship-to-ship, ship-to-shore
and shore-to-ship distress alerting and relaying system using satellites
and terrestrial radio stations with Digital Selective Calling (DSC)
The GMDSS is mandated for international commercial shipping by the IMO
Safety of Life at Sea (SOLAS) Convention 1974, as amended in 1988.
More specific, the IMO has mandated that from 1 February 1999 all passenger
ships and all cargo ships of 300 gross tonnages and upwards on
international voyages must comply with the GMDSS.
Commercial vessels under 300 GRT, such as pleasure yachts,
or those above 300 GRT engaged on domestic voyages only are
subject to the requirements of their Flag State.
Vessels to which the GMDSS requirements apply are classified
as SOLAS vessels while those to which GMDSS requirements do not
apply are considered as non-SOLAS vessels.
GMDSS primary deals with communication and data transmission equipment,
which must enable fast, accurate and reliable distress alerting.
Different communication technologies are available for this purpose
and the choice of equipment depends on the distance that
has to be bridged to the closest land-based Rescue-Coordination Center (RCC).
GMDSS dictates that the communication equipment fitted on board ships depend on
the area of operation of the ship rather than the size.
Because the various communication systems used in the GMDSS have different limitations
with regard to range and services provided, GMDSS divides the world's oceans
into 4 Sea Areas:
Depending on the area being cruised, the following GMDSS equipment may
be required (summary):
- Sea Area 1: is an area within coverage of at least one
VHF coast station in which continuous DSC alerting is available,
nominally in the range of 20 - 30 nautical miles
- Sea Area 2: is an area, excluding Sea Area 1, within the
coverage of at least on MF coast station in which
continuous DSC alerting is available, nominally in the range of 100 -
150 nautical miles
- Sea Area 3: is an area, excluding A1 and A2, within the coverage of
an INMARSAT geo-stationary satellite coast station in which
continuous alerting is available - approximately between 70 degrees
north latitude and 70 degrees south latitude
- Sea Area 4: is the remaining area outside A1, A2 and
A3 (the polar regions)
- VHF radio with Digital Selective Call (DSC),
- VHF hand-held radio,
- MF/HF SSB communication equipment with DSC capability,
- Satellite communication equipment for INMARSAT-B or -C,
- EPIRB (Emergency Position Indicating Radio Beacon) to participate
in the COSPAS-SARSAT Search and Rescue (SAR) system,
- Search-and-Rescue Radar transponder (SART),
- NAVTEX receiver for weather information and navigational
warnings by telex over radio.
Smaller ships and pleasure yachts are non-SOLAS vessels and are
not required to have any GMDSS equipment installed.
However, they may be equipped accordingly by choice and can then participate
in the GMDSS giving access to the global Search-and-Rescue facilities.