General introduction to GMDSS
Global Maritime Distress and Safety System (GMDSS) has been developed by the maritime nations in the International Maritime Organization (IMO) and is the result of their adoption of amendments made in 1988 to the 1974 International Convention on the Safety of Life at Sea (SOLAS).
Based on recent developments in maritime communications, such as satellites and digital technology, GMDSS is designed to ensure maximum availability of safety-related communication for all passenger ships as well as for cargo vessels of 300 GT and upwards engaged in international voyages.*
The goal of GMDSS is to virtually guarantee that complying vessels will be able to communicate with an onshore station at any time, from any location, in case of distress or to exchange safety-related information.
*Ships below 300 gross tonnage as well as those that are not engaged in international voyages are subject to the requirements of the administrations of their flag states.
GMDSS Sea Area
GMDSS defines four sea areas based upon the location and capability of onshore-based communication facilities. The definition of the Sea Areas for GMDSS is outlined below.
Sea Area 
The radiotelephone coverage of VHF coast stations in which continuous alerting by Digital Selective Calling (DSC) is available.
Sea Area 
The radiotelephone coverage of MF coast stations in which continuous alerting by Digital Selective Calling is available.
Sea Area 
The coverage of Inmarsat geostationary satellites.
Sea Area 
Area outside A1, A2 and A3, mostly sea area around polar areas.
System suggestions for GMDSS
General requirement for equipment and functions for all ships irrespective of the operating sea area
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Two-way VHF radiotelephone apparatus
At least two two-way VHF radiotelephone apparatus required for cargo ships of 300-500 GT
At least three two-way VHF radiotelephone apparatus required for all passenger ships and cargo ships of 500 GT and upwards
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Search and rescue locating device (SART: either by radar transponder operating in the 9 GHz band or AIS SART)
At least one SART required for cargo ships of 300-500 GT
At least two SART required for all passenger ships and cargo ships of 500 GT and upwards
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VHF radiotelephone with DSC and DSC Watch Receiver capable of:
‣ Transmission/reception of DSC on CH 70 (156.525 MHz);
‣ Transmission/reception of radiotelephony on CH 6 (156.300 MHz), CH 13 (156.650 MHz) and CH 16 (156.800 MHz); and
‣ Continuous watch on CH 70 (156.525 MHz)
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International NAVTEX Receiver
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406 MHz EPIRB (Emergency Position Indicating Radio Beacon)
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Inmarsat EGC receiver
Required if the ships operate within Inmarsat coverage but outside the international NAVTEX service area. However, ships operating exclusively in areas where an HF direct-printing telegraphy maritime safety information service is provided and fitted with equipment capable of receiving such service may be exempted from this requirement.
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Permanently arranged electrical lighting for illuminating the control panel of the radiocommunications equipment
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Automatic provision of position from an internal or external navigation sensor for all two-way communication equipment that includes ship's position in the distress alert
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Arrangements required only for all passenger ships
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Two-way radiotelephone for on-scene search and rescue communication using frequencies 121.5 MHz and 123.1 MHz
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A distress panel at the conning position
If the satellite EPIRB is used as the secondary means of distress alerting and is not remotely activated, it is acceptable to have an additional EPIRB installed close to the conning position.
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Automatic and continuous update of position for all relevant radiocommunication equipment to be included in the initial distress alert activated through the distress panel
Additional equipment to be installed on ships operating in the Sea Areas: A1 A2
Note: There is no additional equipment required for ships operating exclusively in the Sea Area A1
Functional requirements to be fulfilled by FS-xx75:
- Distress and safety communications on MF (2,187.5 kHz using DSC* and 2,182 kHz using radiotelephony)
*It should be possible that transmission of distress alerts be initiated from the navigation bridge.
- Continuous DSC watch on the frequency 2,187.5 kHz
- Transmission and reception of general communications using radiotelephony or direct-printing telegraphy**
Other functional requirements
Transmission of ship-to-shore distress alerts by radio service other than MF (to be fulfilled by 406 MHz satellite EPIRB)
Maintenance requirement for ships operating in Sea Area A1 and A2
In order to ensure the maintenance requirements specified in SOLAS Reg. IV/15, one of the following measures should be taken as may be approved by the flag administrations:
- Duplication of equipment;
- Shore-based maintenance; or
- At sea electronic maintenance capability
Please consult with the flag administrations for details.
Additional equipment to be installed on ships operating in the Sea Areas: A1 A2 A3
Inmarsat Solution
Functional requirements to be fulfilled by FELCOM18*:
- Transmission and reception of distress and safety communications using direct-printing telegraphy
- Initiation and reception of distress priority calls
- Continuous watch on shore-to-ship distress alerts, incl. those directed to specially defined geographical area
- Transmission and reception of general communications using either radiotelephony or direct printing telegraphy
*It should be possible that transmission of distress alerts be initiated from the navigation bridge.
Functional requirements to be fulfilled by FS-xx75*:
- Distress and safety communications using the following frequencies:
- 2,187.5 kHz using DSC and continuous DSC watch
- 2,182 kHz using radiotelephony
*It should be possible that transmission of distress alerts be initiated from the navigation bridge.
Other functional requirements
Initiation of transmission of ship-to-shore distress alerts* to be fulfilled by one of the followings:
- 406 MHz satellite EPIRB
- HF using DSC
- Inmarsat-C Mobile Earth Station
*It should be possible that transmission of distress alerts be initiated from the navigation bridge.
OR
MF/HF Solution
Functional requirements to be fulfilled by FS-xx75* plus IB-585:
- Distress and safety communications on all distress and safety frequencies on MF and HF bands
using DSC / using radiotelephony / using direct printing telegraphy
- Continuous DSC watch on 2,187.5 kHz, 8,814.5 kHz, and on at least one of the distress and safety frequencies:
4,207.5 kHz, 6,312 kHz, 12,577 kHz or 16,804.5 kHz
- Trasnsmission and reception of general radio communications using radiotelephony or direct-printing telegraphy by MF/HF radio installation
*It should be possible that transmission of distress alerts be initiated from the navigation bridge.
Functional requirements to be fulfilled by FELCOM18*:
- Initiation of the transmission of ship-to-shore distress alert by radio services other than HF
*It should be possible that transmission of distress alerts be initiated from the navigation bridge.
Maintenance requirement for ships operating in Sea Area A3
In order to ensure the availability of the maintenance requirements specified in SOLAS Reg. IV/15.7, combination of at least two of the following methods should be taken as may be approved by the flag administrations, while taking into account the recommendation specified in IMO A.702(17):
- duplication of equipment;
- shore-based maintenance; or
- at-sea electronic maintenance capability.
All ships irrespective of the methods used should make all manufacturers’ installation manuals and maintenance manuals for all the equipment installed available.
Adequate tools, spare parts and test equipment appropriate to the methods used by the ship, as specified by the flag administration should be provided and readily available onboard.
Duplication of equipment
1. VHF radio installation capable of transmitting/receiving DSC on CH 70 as well as radiotelephony on CH 6, 13 and 16 as well as contionuous DSC watch on CH 70 and either of the radio installations listed as 2-a or 2-b below should be arranged onboard:
2-a. MF/HF radio installation for distress and safety communications on the frequency bands between 1,605 kHz and 4,000 kHz and between 4,000 kHz and 27,500 kHz, using DSC, radiotelephony and directprinting telegraphy. Continuous DSC watch on 2,187.5 kHz, 8,814.5 kHz and on at least one of the distress and safety frequencies: 4,207.5 kHz, 6,312 kHz, 12,577 kHz or 16,804.5 kHz is also required.
2-b. Inmarsat MES capable of transmission/reception of distress and safety communications using direct-printing telegraphy, initiation/reception of distress primary calls, continuous watch on shore-to-ship distress alerts, incl. those directed to specifically defined geographical area, and transmission/reception of general communications using either radiotelephony or direct-printing telegraphy
Shore-based maintenance
An arrangement acceptable to the flag administration should be established to ensure adequate support of the ship for the maintenance and repair of the radio installations, i.e., service agreement with a capable service provider covering the trading area of the ship.
At-sea electronic maintenance capability
Adequate additional technical documentations, tools, spare parts and test equipment consistent with radio installation as approved by the flag administration should be provided onboard so that the maintainer can perform tests and localize and repair faults in the radio equipment while at sea.
The person who is to conduct at-sea electronic maintenance should either hold an appropriate certificate as specified by the Radio Regulations or have equivalent at-sea electronic maintenance qualifications as may be approved by the flag administration, taking into account the reccomendation specified in Annex 5 of IMO A.703(17).
Additional equipment to be installed on ships operating in the Sea Areas: A1 A2 A3 A4
Functional requirements to be fulfilled by FS-xx75* plus IB-585:
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Distress and safety communications on all distress and safety frequencies on MF and HF bands
- using DSC
- using radiotelephony
- using direct printing telegraphy
- Continuous DSC watch on 2,187.5 kHz, 8,814.5 kHz, and on at least one of the distress and safety frequencies:
4,207.5 kHz, 6,312 kHz, 12,577 kHz or 16,804.5 kHz
-
Trasnsmission and reception of general radio communications using radiotelephony or direct-printing telegraphy by MF/HF radio installation
*It should be possible that transmission of distress alerts be initiated from the navigation bridge.
Other functional requirements:
Initiation of the transmission of ship-to-shore distress alert by radio services other than HF**
**Inmarsat C MES cannot satisfy the requirement, and this shall lead to the assumption that 406 MHz Satellite EPIRB is the only option available to satisfy the functional requirement.
Maintenance requirement for ships operating in Sea Area A3 and A4
In order to ensure the availability of the maintenance requirements specified in SOLAS Reg. IV/15.7, combination of at least two of the following methods should be taken as may be approved by the flag administrations, while taking into account the recommendation specified in IMO A.702(17):
- duplication of equipment;
- shore-based maintenance; or
- at-sea electronic maintenance capability.
All ships irrespective of the methods used should make all manufacturers’ installation manuals and maintenance manuals for all the equipment installed available. Adequate tools, spare parts and test equipment appropriate to the methods used by the ship, as specified by the flag administration should be provided and readily available onboard.
Duplication of equipment
1. VHF radio installation capable of transmitting/receiving DSC on CH 70 as well as radiotelephony on CH 6, 13 and 16 as well as contionuous DSC watch on CH 70; and
2. MF/HF radio installation for distress and safety communications on the frequency bands between 1,605 kHz and 4,000 kHz and between 4,000 kHz and 27,500 kHz, using DSC, radiotelephony and direct-printing telegraphy. Continuous DSC watch on 2,187.5 kHz, 8,814.5 kHz and on at least one of the distress and safety frequencies: 4,207.5 kHz, 6,312 kHz, 12,577 kHz or 16,804.5 kHz is also required.
Shore-based maintenance
An arrangement acceptable to the flag administration should be established to ensure adequate support of the ship for the maintenance and repair of the radio installations, i.e., service agreement with a capable service provider covering the trading area of the ship.
At-sea electronic maintenance capability
Adequate additional technical documentations, tools, spare parts and test equipment consistent with radio installation as approved by the flag administration should be provided onboard so that the maintainer can perform tests and localize and repair faults in the radio equipment while at sea.
The person who is to conduct at-sea electronic maintenance should either hold an appropriate certificate as specified by the Radio Regulations or have equivalent at-sea electronic maintenance qualifications as may be approved by the flag administration, taking into account the reccomendation specified in Annex 5 of IMO A.703(17).
Note:
For ships operating in the sea area A4 only occasionally but mostly operating in A3, Inmarsat C MES may be installed for duplication in lieu of MF/HF radiotelephone with built-in DSC plus NBDP terminal, provided that the ship has originally MF/HF radio installation.
