Portable Radio Apparatus for Survival Crafts

Communication in an emergency is essential and in some cases, it is crucial for the survival of the crew. However, there are other circumstances than a life-or-death situation where communication is vital. In this step, you will learn more about different communications tools and their purpose. 

Portable VHF Radios

VHF radio is a worldwide system of two-way radio voice communication from ship-to-ship, ship-to-shore and in certain circumstances ship-to-aircraft. It uses FM channels in the very high frequency (VHF) radio band in the frequency range between 156 and 174 MHz.

All ships of more than 300 tons gross tonnage must be provided with at least two portable VHF radios. Onboard vessels of more than 500 tons gross tonnage and all passenger ships, at least three portable VHF radios, should be provided. These radios are developed to allow communication between SAR vessels and survivors in liferafts. They operate on the VHF marine band and comply with a unique performance standard that is adopted by the IMO.

Emergency Position-Indicating Radio Beacon (EPIRB)

An EPIRB is a device to alert search and rescue services (SAR) in case of an emergency out at sea. EPIRBs are included in the vessel's GMDSS communication equipment. An EPIRB looks like a small buoy and the beacon can be activated manually or automatically. The signals make it possible to localise the EPIRB's position, primarily from a ship, plane or satellite, depending on the frequencies used. There are two types of EPIRBs approved by SOLAS:

• COSPAS-SARSAT EPIRB – sending distress alerts through the polar-orbiting satellite service operating in the 406 MHz band, and
• INMARSAT EPIRB – sending distress alert through the Inmarsat geostationary satellite service operating in the 1.6 GHz band.

Which one to use depends on the area the yacht operates.

The EPIRB also sends a low power signal on 121.5 MHz, which can be detected by an overflying aircraft. This provides significant aid to the search and rescue aircraft to locate those in distress. This function is called "Homing".

The requirements for what type of EPIRB a ship has to carry varies with the sea area the ship is intended to operate. Yachts that operate solely in sea area A1 (coastal), only need one EPIRB capable of transmitting a distress alert using DSC on VHF channel 70.

Yachts operating in sea areas A2, A3 (worldwide except polar regions) and A4 (polar regions), one EPIRB is required to be carried provided it transmits on 406 MHz and is installed close to or by remote activation from the 'bridge'. The EPIRB is available in a model that can be hung on the bulkhead. This makes it easy to bring along in a boat or raft. Another model is placed high up in the yacht, with hydrostatic release and automatic activation if the ship should go down. The latter model can also be removed from its canister and brought along in the boat or raft.

Automatically or Manually Activation

The EPIRB can either be activated automatically when submerged in seawater or manually by moving a switch on the EPIRB to the ON position. Accidental activation or false alerts are most of the time caused by user errors. It could be by removing the EPIRB from its bracket without properly disarming it or not following proper test or inspection procedures. It can also accidentally be activated due to not reading the EPIRB's user manual. 

Low or expired batteries or close contact with magnets can sometimes cause a beacon to activate accidentally. If an EPIRB is accidentally activated and not reported to an MRCC, the Search And Rescue (SAR) operation will start. This operation involves a lot of different resources, tying up these search and rescue resources means that valuable time could be lost if a real distress occurs in the same area.

The EPIRB is transmitting the distress alert on either 406 MHz or 1.6 GHz. The distress alert message contains the following information:

• A serial number of the EPIRB.
• Call sign or MMSI number.
• An activated SART which picks up the radar wave from a plane or a ship will send a signal consisting of a number of dots that are visible on the radar screens.

Search and Rescue Transponders (SART)

A radar transponder is included in the vessel's GMDSS communication equipment. The purpose of a radar transponder is to attract attention from a ship or plane within the radar range. The transponder operates in the 9 GHz band (X-band). All yachts must carry a radar transponder/SART onboard, positioned where it can quickly be brought along in the boat or raft.

Every cargo ship of 300–500 tons gross tonnage has to carry at least one radar transponder, positioned where it can easily be brought along in any survival craft. Every passenger ship and cargo ships of more than 500 tons gross tonnage have to carry at least one radar transponder on each side of the ship, positioned where it can easily be brought along in any survival craft.

If a ship is carrying at least two radar transponders and equipped with free-fall lifeboats, one of the radar transponders shall be stowed in a free-fall lifeboat. The other should be located near the navigation bridge so that it can be ready for transfer to any of the other survival craft.

Manually Activated

The SART is activated manually by sliding a switch to the ON position. Although the transponder does not send an alarm via satellite, VHF or other radio communication, the use should be limited to short tests and emergencies. This is to save battery capacity in case of a situation where the transponder is needed. If a SART is accidentally activated, it will start transmitting if there is nearby traffic and a 9 GHz radar signal hits the SART. The typical SART pattern will be received and shown on the nearby vessels' X-band radar screen, making them believe that it is a distress situation.

An activated SART which picks up the radar wave from a plane or a ship will send a signal consisting of several dots that are visible on the radar screens. The closer the vessel detecting the SART gets, the dots become arches and eventually full circles.