GMDSS

Question 1

What is GMDSS?

Answer 1

Global Maritime Distress Safety System is a internationally agreed set of safety procedures, types of equipment and communication protocols used to increase safety at sea and assist in the rescue of distressed ships, boats and aircraft.

Question 2

What is GMDSS used for?

Answer 2

GMDSS is used to:

• Send emergency and distress messages
• Vessel to vessel routine communications
• Vessel to shore communications

Question 3

Who is required to carry GMDSS equipment?

Answer 3

As per SOLAS ch IV, all passenger ships and cargo ships over 300gt are required to comply with GMDSS

Question 4

What are the SEA AREAS of GMDSS?

Answer 4

The sea areas are:
- A1 = Within range of a VHF coast station continuously monitoring CH 70

• A2 = Excluding A1, within range of at least one MF coast station with continuous watch on 2187.5kHz
• A3 = Excluding A1 + A2, within coverage of an INMARSAT satellite up to 76’N and 76’S
• A4 = Outside of A1 + A2 + A3, includes the polar regions, above 76’N + 76’S

Question 5

What equipment is require for each SEA AREA?

Answer 5

For each area:

• A1 = VHF DSC
• A2 = VHF + MF
• A3 = VHF + MF + one INMARSAT
• A4 = VHF + MF + INMARSAT + HF + EPIRB

Question 6

How would you send a distress?

Answer 6

RT:

MAYDAY x 3
Vessel name x 3
Call Sign and MMSI number

Message:

Mayday
Vessels name, Call sign, MMSI number, 
Latitude and Longitude, 
Nature of distress,
Require immediate assistance, 
additional information
Over

Question 7

What are the different types of distress calls?

Answer 7

Mayday = This is used when a vessel or people are threatened by grave and imminent danger and requires immediate assistance.

PanPan = This is the urgency signal and is used when the safety of a vessel or a person is at risk.

SECURITE = This is the safety signal and is used to advise others about important navigation or weather warnings that may impact the safety of other vessels.

Question 8

What is VHF DSC?

Answer 8

A Very Hugh Frequency radio is used to communicate on specific channels the radio is programmed to operate on. Channel 16 is used to send distress, urgency and safety messages.

DSC is Digital Selective Calling this can be used to send designated / undesignated distress through channel 70 which has to followed by a RT voice distress.

Question 9

What is NAVTEX?

Answer 9

NAVTEX is an automated direct printing service which is used to distribute Maritime Safety Information (MSI). MSI’s include nav warnings, met warnings and urgent information to ships. It operates on two frequency’s:
- 518KHz which is the international broadcast
- 490KHz which is for local broadcasts
You can find more information about the broadcasts in the ALRS volumes 3 and 5. NAVTEX can choose which messages they receive but these cannot be disabled:
- A = nav warnings
- B = Met warnings
- D = SAR information
- L = Additional nav warning to A

Question 10

What is an INMARSAT?

Answer 10

INMARSAT is a satellite system that allows telex, telephone and data transfers services between ship to ship, ship to shore and shore to ship. There are a few different types of INMARSAT B, C and F77.

Question 11

What is an EPIRB?

Answer 11

A electronic position indicating radio beacon is a device used in as a means of distress which allow search and rescue services to the location of a ship, lifeboat or liferaft. It operates on 406MHz and 121.5MHz frequencies.

Question 12

What is a SART?

Answer 12

A search and rescue transponder is used to locate a ship or liferaft by radar. The SART is operated on 9GHz so can only be interrogated with the X-band radar, it will firstly appear as 12 dots, then as you get closer change to 12 arcs and finally 12 circles.

Question 13

What daily tests do you carry out on GMDSS equipment?

Answer 13

A daily test includes:

• Testing the function of all DSC facilitated equipment that is carried onboard (transmit/receive)
• Test all batteries used to provide a reserve power supple to all radio equipment
• Test handheld radios

Question 14

What weekly tests do you carry out on GMDSS equipment?

Answer 14

A week test includes:

- Test for the proper operation of the DSC equipment carried onboard by performing a test call to a coast station

Question 15

What monthly tests do you carry out on GMDSS equipment?

Answer 15

A monthly test includes:

• Testing all EPIRB’s and SART’s carried onboard, including visual inspections of equipment and mounts.
• Test two-way VHF’s carried in all survival craft.
• Visual check of aerials systems for signs of corrosion or damage

Question 16

What are your actions when receiving a DSC alert on channel 70?

Answer 16

On receiving a DSC alert I firstly would stop the sound by pressing next by the the DSC would change to the required channel the distress will be transmitted on. Listen to all information passed and take no further action unless required by the RCC.

Acknowledgment of a distress alert should only be performed by a shore-based station, assume the distress has been heard and acknowledged by a coast station.

Question 17

What are your actions when receiving a DSC alert on channel 70 when in sea areas A2 and above?

Answer 17

I would acknowledge the DCS alert and assume the responsibility of informing the nearest coast station by carrying out a MAYDAY RELAY.

Question 18

How would send a MAYDAY RELAY?

Answer 18

RT: Relay station info

MAYDAY RELAY x 3
Coast Station x 3 or All Stations x 3
This is 
Name x 3 
C/S x 1 
MMSI x 1

Message: Distress station info
MAYDAY
Name + C/S + MMSI or Unidentified vessel 
Position
Nature of distress
Assistance required 
POB
Other Information 
Over

Question 19

What are some other distress signals?

Answer 19

In annex 4 of Colregs you can use this signals:

• A gun or other explosive fired at intervals of 1 minute
• Morse code SOS signal …—…
• Flag signal N.C
• Flames on the vessel (Oil barrels or tar barrels)
• MF/HF frequencies 2187.5kHz, 4207.5kHz, 6312kHz, 8414.5kHz, 12577kHz or 16804.5kHz