Safety at Sea

Tried and trusted communications

Paul Gunton
Paul Gunton

14 March 2019

Tried and trusted communications

Over the centuries, the ways in which ships can signal a need for assistance have changed. This process has been a slow journey and only since the days of radio and satellites have ships been able to signal beyond the horizon.

Today when a ship is in distress, alerting potential rescuers is almost always first done using the ship’s GMDSS equipment. This should initiate a search and rescue operation when additional resources will be directed to the ship in distress. The equipment required under GMDSS is described in the ShipInsight Communication Guide. The main alerting method in GMDSS is the ship’s EPIRB which should also be taken into a lifeboat if the ship is abandoned.

As well as their GMDSS systems, ships also carry other means of requesting assistance. Some of these are described in the ShipInsight Navigation and Bridge Guide and include lamps and sound signals.

Under the ISPS Code, ships are required to be fitted with a Ship Security Alert System that can be operated covertly in cases of piracy or similar threat. Most work on satellite communication systems and an alert made via the SSAS is only received by the competent authority ashore and not by other ships. The regulations state that a transmission initiated by security alert system activation points should include a unique code/identifier indicating that the alert has not been generated in accordance with GMDSS distress procedures. The transmission should include the ship identity and current position and should be addressed to a shore station and not to ship stations.

Although personal locator beacons (PLB) are not intended to be a replacement for SOLAS equipment, some seafarers carry their own PLBs in case they are either lost overboard or need to take to lifeboats. A PLB is a relatively new development which employs the same principal as an EPIRB and transmits a radio signal on the 406MHz wavelength that will be picked up by ships’ GMDSS stations. They are small battery-powered devices about the size of a large mobile phone or small walkie talkie that can be easily carried in a pocket or on a belt clip. Depending on the maker – the numbers of which are growing – the battery is usually of the lithium ion type with a life span of up to six years. They will normally transmit a signal for a minimum 24 hours.

The issue of PLBs is not covered under SOLAS so their availability to crew may be limited by the generosity or otherwise of the ship operator. They are however relatively inexpensive and well within the means of most seafarers to purchase for themselves.

Traditional distress systems

For cases where use of GMDSS equipment is impossible and for attracting attention of search and rescue aircraft and ships, the use of pyrotechnics is called for and required under SOLAS. The universally-known red distress flare is the most useful for attracting attention over a distance, with hand flares and smoke being used for shorter distances.

A rocket parachute flare can be seen from a distance of up to 30 nautical miles under optimum conditions at night and from eight nautical miles during daylight. SOLAS requires ships to maintain a stock of at least 12 flares on the bridge and no less than four in each lifeboat or liferaft.

Hand-held flares and smoke signals have a much shorter range and are intended to allow search and rescue craft to pinpoint the position of any survival craft. Each lifeboat or liferaft should be equipped with six hand flares, two buoyant smoke signals and an electric torch with spare batteries and bulbs suitable for Morse signalling. Also in the survival craft should be a signalling mirror, whistle and a copy of the life-saving signals on a waterproof card.

Pyrotechnics have an expiry date and should be replaced before they expire. Failure to have sufficient pyrotechnics on board and in survival craft will cause a ship to be detained by PSC inspectors. Pyrotechnics should only be used when there is reasonably good chance that they will be seen. Parachute flares burn for a minimum of 40 seconds falling from a height of about 300m. Instructions for use should be printed on the flare, presented in a picture format.

Hand flares are used to guide the searching ship or aircraft or pinpoint the survivors’ position. They burn for a minimum of one minute and are ideal for day or night use and have a range of five nautical miles by day and 10 nautical miles at night.

Smoke signals use to raise an alarm is doubtful but they can be used to pinpoint the survivors’ position. They will be more readily seen from an aircraft than a surface craft. They are for daytime use only and smoke for a minimum of three minutes. Their range is at the most about two to three nautical miles in good visibility.

Close quarter rescues

As well as the use of lifebuoys, passing a line to a person in the water or across to another vessel is often essential in emergencies so it is not surprising that there is a mandatory requirement to carry a line-throwing appliance. SOLAS says that the line thrower should:

  • be capable of throwing a line with reasonable accuracy;
  • include not less than four projectiles each capable of carrying the line at least 230m in calm weather;
  • include not less than four lines each having a breaking strength of not less than 2kN;
  • have brief instructions or diagrams clearly illustrating the use of the line-throwing appliance.
  • The rocket, in the case of a pistol-fired rocket, or the assembly, in the case of an integral rocket and line, shall be contained in a water-resistant casing. In addition, in the case of a pistol-fired rocket, the line and rockets together with the means of ignition shall be stowed in a container which provides protection from the weather.