GMDSS, or the Global Maritime Distress and Safety System, is an international communication system established by the International Maritime Organisation (IMO) to enhance safety and facilitate rescue operations at sea. It ensures that ships in distress can send alerts and communicate with search and rescue authorities, as well as nearby vessels, regardless of their location on the globe.

GMDSS uses a combination of satellite and terrestrial radio systems, including EPIRBs (Emergency Position Indicating Radio Beacons), SARTs (Search and Rescue Transponders), NAVTEX, Inmarsat, and VHF, MF, and HF radios. The system is mandatory for all SOLAS-compliant ships (Safety of Life at Sea) and is divided into different sea areas (A1 to A4), based on the type of radio coverage available. GMDSS improves the speed, reliability, and coverage of distress communication, significantly increasing the chances of timely rescue in maritime emergencies.

 

What are GMDSS Quizzes?

 

 

GMDSS quizzes are an effective tool for reinforcing knowledge and assessing understanding of the Global Maritime Distress and Safety System. Designed for students, cadets, and certified seafarers alike, these quizzes cover a range of topics including radio procedures, equipment functions, satellite communication systems, and distress protocols.

Regular practice with quizzes helps build confidence in using communication equipment correctly during emergencies and ensures familiarity with international standards set by the International Maritime Organisation (IMO).

 

Test your knowledge with our quizzes

Here’s a set of GMDSS questions designed to test and reinforce your understanding of this vital maritime communication system.

 

 

Information on GMDSS Certificates

Types of GMDSS Certificates

ROC

The Restricted Operator’s Certificate (ROC) is designed for seafarers who operate GMDSS radio equipment in Sea Area A1, which typically covers areas within VHF radio range of coast stations—about 20 to 30 nautical miles offshore.

Who needs an ROC?

  • Required for crew members on small commercial vessels, fishing boats, yachts, and passenger ships operating only in coastal or short-range sea areas.

  • Common for masters or skippers of smaller vessels who must communicate using VHF DSC radio equipment.
GOC

The General Operator’s Certificate (GOC), and it is an internationally recognised qualification that permits the holder to operate GMDSS (Global Maritime Distress and Safety System) radio equipment on ships operating in all sea areas (A1 to A4).

Who needs a GOC?

  • It is required for Deck Officers, Radio Operators, and others who are responsible for radio communication at sea.
  • The GOC certifies that a seafarer is competent to handle all types of maritime communication systems necessary for safety and coordination in global shipping operations.
LRC

The LRC is an ITU (International Telecommunication Union)-approved certificate that allows holders to legally operate MF/HF radios, VHF radios, and Digital Selective Calling (DSC) equipment, particularly when sailing outside coastal (Sea Area A1) waters. It is not equivalent to the GOC, which is required for professional merchant navy use under SOLAS regulations.

Who needs LRC?

  • Yacht skippers and crew operating in Sea Areas A2 and A3
  • Recreational sailors and offshore cruisers
  • Anyone using SSB (single sideband) marine radios or Inmarsat equipment on private or non-SOLAS vessels
SAT MOD

The SAT MOD (Satellite Module) is required for individuals who are training to operate GMDSS equipment on vessels that sail outside Sea Area A1, particularly into Sea Areas A2 and A3, where shore-based radio coverage is limited or unavailable, and satellite communication is essential.

Who needs SAT MOD?

  • Anyone pursuing the GOC, which is required for operating GMDSS equipment on SOLAS-compliant vessels in all sea areas (A1–A4), must complete the SAT MOD.
  • Officers responsible for radio communication on ships that operate internationally or far from shore, where Inmarsat systems are used for distress and routine communication.
     
  • Personnel who handle satellite distress alerts, SafetyNET, and Inmarsat-C messaging systems onboard.
     
  • Especially relevant to those preparing to work on vessels in remote oceanic regions, deep-sea shipping, or long-distance passenger ships.

Applying for a UK GMDSS Certificate, Endorsement or Revalidation

If you are a radio operator seeking a GMDSS GOC, ROC, or LRC, you must apply to the Maritime and Coastguard Agency (MCA) to obtain your Certificate of Competency.

Additionally, if you are serving on a UK-registered vessel, you must apply to the MCA to have your GMDSS GOC or ROC endorsed in accordance with STCW requirements.

Applying for a UK GMDSS Certificate

 

The GMDSS (Global Maritime Distress and Safety System) certificates are mandatory for seafarers operating radio and communication equipment on seagoing vessels. These certificates are governed by the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW).

How to apply