Everything You Need To Know About Liferafts On Ships

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Life rafts are survival equipment provided as a life-saving appliance on every seagoing merchant or passenger ship, in addition to the lifeboats.

Easier To Launch 

Life rafts are much easier to launch than lifeboats. In emergencies, evacuation from the ship can be done without manually launching any of them, as the life rafts are designed with an auto-inflatable system.

SOLAS Chapter III gives all the details for the types, and the number of life rafts to be carried according to the size and type of the ship.

Where Are They Located?

Life rafts are typically located on the muster station, on the port and starboard side near the lifeboat, and on the aft of the ship. The location generally depends on the size of the ship. Life rafts are stored in a fibreglass container, and a high-pressure gas inflates them during an emergency.

A Hydrostatic Release Unit (HRU) is connected to the raft container and ship, which releases the raft even after the vessel sinks in water.

Important Solas Requirements

  • All liferaft provided on ships should be bestowed with its painter permanently attached to the vessel.
  • Each liferaft or group of liferafts should be stowed with a float-free arrangement complying with the requirements so that each floats free. If it is an inflatable raft, it should inflate automatically when the ship sinks.
  • Liferafts should be stowed to permit the manual release of one raft or container at a time from the securing arrangements.
  • Davit-launched liferafts should be stowed within reach of the lifting hooks unless some transfer is provided, which is not rendered inoperable within the limits of trim and list as required or by ship motion or power failure.
  • Liferafts intended for throw-overboard launching should be stowed to be readily transferable

Essential Requirements for Liferafts 

The liferaft of any ship needs to follow the regulations mentioned in SOLAS. Some of the important points regarding liferafts are:

  • The lift raft should be capable of withstanding exposure for 30 days afloat in all sea conditions
  • When dropped into the water from a height of 18 metres, the life raft and all equipment in it will operate satisfactorily.
  • The floating life raft should be capable of withstanding repeated jumps on it from a height of at least 4.5 metres above its floor, both with and without the canopy erected.
  • It can be towed at 3 knots with its complete equipment, complement of persons and one anchor streaming.
  • Canopy to provide insulation and protection against heat and cold by two layers of material separated by an air gap
  • Interior to be of a non-discomforting colour.
  • It shall admit sufficient air for the occupants at all times, even when the entrance is closed
  • It shall be provided with at least one viewing port
  • It will be given with a means of collecting rainwater
  • It shall be provided with a tool to mount a survival craft radar transponder (SART) at the height of at least 1 meter above the sea level
  • It shall have sufficient headroom for the sitting occupants under all parts of the canopy
  • The minimum carrying capacity must be at least six persons
  • The maximum weight of its container, as well as the equipment, should not exceed 185 kilos
  • The life raft shall be fitted with an efficient painter of length equal to the minimum of 10 metres plus the distance from the stowed position to the waterline in the lightest seagoing condition or 15 metres, whichever is greater
  • A manually controlled lamp shall be fitted on the top of the canopy, and the light shall be white, and it must operate for at least 12 hours with a luminous intensity of not less than 4.3 candela
  • If the flashlight is fitted, it shall flash at a rate of not less than 50 flashes and not more than 70 flashes per minute for the 12 hours that it burns
  • A manually controlled lamp shall be fitted inside the life raft, capable of continuous operation for at least 12 hours
  • When the liferaft is loaded with a full complement of persons and equipment, it should be capable of withstanding a lateral impact against the ship side at an impact velocity of not less than 3.5m/s and also drop into the water from a height of not less than 3 metres without damage
  • CO2 does inflation with a small quantity of N2, which acts as an anti-freezing element. Also, CO2 is non-flammable and weighs more than air, adding buoyancy to the raft. The freezing point of CO2 is -78 degrees so that it can inflate life rafts at shallow temperatures

Safety Features on a Liferaft

Some of the main safety features on a liferaft are:

  • Pressure relief valve
  • Stabilizing pocket
  • Insulated canopy with two layers for protection against heat and cold

Markings On a Liferaft Container

Important markings provided on a liferaft container are:

  • Maker’s name and trademark
  • Serial number
  • Name of Authority
  • Number of persons carried
  • SOLAS emergency pack enclosed
  • Date of the last service
  • Length of painter
  • Maximum height of stowage
  • Launching instructions

Launching The Life Raft Manually

  • Take out the painter of the raft
  • Fasten it to the ship side at a strong point
  • Remove the railing and check overboard for any obstructions
  • Unfasten the hook from the cradle
  • Two people can lift the life raft and throw it overboard
  • After it’s thrown, pull the painter sharp until the life raft inflates
  • With the painter, pull it towards the ship’s side
  • Lower the embarkation ladder or jump directly onto the life raft, depending on the situation and the time at hand
  • Sit wide order face to face to prevent any imbalance
  • Ensure SART and EPIRB have been carried
  • Take a headcount
  • Cut the painter using the knife, paddle, or anchor, clear away from the ship.

Launching The Life Raft by the Davit

  • Remove the ship’s handrail
  • Remove lashings from the container
  • Lower the davit and lock it with the lifting shackle
  • Secure canister lines outboard
  • Secure browsing line
  • Pull the painter out approximately 5-6 metres
  • Secure the painter’s line
  • Pull the entire length of the painter
  • Now lift the life raft canister to some height
  • Pull the painter sharply and let it inflate
  • After it inflates, secure the liferaft
  • One person should go in and make some checks
  • Collect the SART and EPIRB
  • Go inside and sit evenly
  • Release the bowsing line and pass to the raft
  • Check if the launching area is clear
  • Lower the raft using the brake release
  • Operate hook release 1m above the water or allow the raft to ride a crest of the wave to put the load on the water, and it will automatically release
  • Cut the painter and clear away

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Source: MarineInsight