12/09/2025
SHIP'S NAVIGATION | BRIDGE & GMDSS
✳️ ( ) equipment includes a variety of radio and satellite communication devices that are essential for maritime safety.
Key components include VHF DSC and MF/HF DSC equipment for distress alerting, NAVTEX receivers for receiving navigational and weather warnings, and EPIRBs (Emergency Position Indicating Radio Beacons) for alerting search and rescue authorities.
➕ Additionally, SARTs (Search and Rescue Radar Transponders) and portable VHF transceivers are crucial for on-scene communication and rescue operations.
✳️GMDSS Equipment Breakdown:
✅ (Digital Selective Calling):
A radio system using digital signaling for distress alerts and other communications.
✅ (Medium Frequency/High Frequency DSC):
Similar to VHF DSC but used for longer-range communication, particularly in areas where VHF coverage is limited.
✅ :
An automated system for broadcasting maritime safety information, including navigational warnings, weather forecasts, and search and rescue information.
✅ (Emergency Position Indicating Radio Beacon):
A device that transmits a distress signal, including the ship's position, to search and rescue authorities via satellite.
✅ (Search and Rescue Radar Transponder):
A device that responds to radar signals from search and rescue vessels, helping them locate survivors in distress.
✅ :
Handheld radios used for on-scene communication during search and rescue operations.
✅ / :
Satellite communication systems for two-way data and messaging, especially in areas beyond VHF and MF/HF coverage.
✅ (Automatic Identification System):
A system for transmitting and receiving ship information, including position, course, and speed.
Power Supply:
✳️GMDSS equipment is required to have a robust power supply, typically including:
💊Normal ship's alternators/generators.
💊An emergency alternator/generator (if fitted).
💊Dedicated radio battery supply with sufficient capacity to power equipment for a set duration (e.g., 1 hour with an emergency generator, 6 hours without).
💊Automatic battery chargers.
Testing and Maintenance:
Regular testing and maintenance of GMDSS equipment are essential to ensure its proper functioning in emergencies.
This includes:
⚠️ Daily, weekly, and monthly tests:
These tests are typically conducted by the ship's crew to verify the operational status of the equipment.
⚠️ Annual surveys:
These surveys are conducted by shore-based personnel to assess the overall condition and compliance of the equipment with GMDSS regulations.
Operator Qualifications:
GMDSS equipment operation requires qualified personnel.
Depending on the specific equipment and its role, different types of qualifications may be needed, such as:
🛑 First and Second Class Radio-Electronic Certificates for technical maintenance.
🛑 GMDSS General Operator's Certificate for navigating officers.
✳️ Area of Operations
provides that “…every ship shall be provided with radio installations capable of complying with the functional requirements … throughout the intended voyage …”.
Thus, every ship must carry a core set of basic equipment that is applicable to all waters, supplemented by additional equipment that extends the ship’s communications capabilities according to areas of operation. These supplementary requirements are defined by the distance offshore the ship will travel:
📌
The area within the radiotelephone coverage of at least one very high frequency (VHF) coast station in which continuous DSC alerting is available.
📌
The area, excluding sea area A1, within the radiotelephone coverage of at least one medium frequency (MF) coast station in which continuous DSC alerting is available.
📌
The area, excluding sea areas A1 and A2, within the coverage of a recognized mobile satellite service supported by the ship earth station carried on board in which continuous alerting is available.
📌
An area outside sea areas A1, A2 and A3.
✳️Use of recognised mobile satellite services
Recognised mobile satellite services ( ) play a crucial role in GMDSS by providing a means of communication in areas outside Sea Areas A1 and A2.
The following services have been recognised by IMO and are in operational use:
• Inmarsat C
• Fleet Safety (in the coverage area of the Middle East and Asia region)
• Iridium Safety Services
IMO has also recognized the BeiDou Message Service System (BDMSS) for use in the pending the completion of its implementation.
✳️Application
The GMDSS generally applies to all ships of 300 gross tons and upwards on international voyages. However, the GMDSS is of equal valuable for other vessels, including recreational and other vessels which do not have a mandatory requirement under SOLAS to install equipment. GMDSS carriage requirements are also applied to some fishing vessels by national legislation✅✅✅
