Life rafts are survival equipment provided as a life-saving appliance on every seagoing merchant or passenger ship, in addition to the lifeboats.
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 types and the number of life rafts to be carried as per the size and type of the ship.
Where Are Liferafts Located On Ships?
Life rafts are normally located on the muster station, on the port and starboard side near the lifeboat, and fwd and aft of the ship. The location generally depends on the size of the ship.
Life rafts are stored in a fibreglass container, with a high-pressure gas used to inflate life rafts 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.
The particulars of the raft are stencilled on the container, which includes the capacity, manufacturing date, servicing date, company name etc., along with the launching procedure with a photogenic display for easy understanding.
The essential survival items are already stored in the raft, including rations, pyrotechnics, life jackets etc.
Some ships carry a davit launching system that allows the crew to inflate and board the raft on the deck, avoiding the risk of entering the seawater.
Important Solas Requirements For Life Rafts
- 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 for launching on either side of the ship.
Servicing of Liferafts
All liferafts shall be serviced:
- at intervals not exceeding 12 months (if impracticable, the administration may extend this period to 17 months)
- at proper service stations with proper servicing facilities and trained professionals
Davit-launched liferaft automatic release hooks should be maintained following instructions for onboard maintenance
Essential Requirements for Liferafts and Carrying Capacity
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
- Location on a ship:
– At embarkation stations on both port and starboard sides
- The painter breaking strength should be:
– 15kN for 25 people and more
– 10 kN for 9 to 24 people
– 7.5 kN Rest (6-9)
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
Important Liferaft Equipment
All liferafts on ships are fitted with the following equipment:
- Rescue quoits with minimum 30-metre lines
- Non-folding knives with buoyant handles
- For 12 persons or less, one bailer. For more than 13 persons, 2 bailers should be kept.
- Two sponges
- Two buoyant paddles
- Three tin openers
- Two sea anchors
- One pair of scissors
- One first aid waterproof kit
- One whistle
- One waterproof torch for communicating morse code with one spare set of batteries and bulb
- One signalling mirror/heliograph
- One radar reflector
- One life-saving signal waterproof card
- One fishing tackle
- Food ration totalling not less than 10000 kJ for each person
- Water ration- 1.5 litres of fresh water for each person
- One rustproof graduated drinking vessel
- Anti-seasickness medicine is sufficient for at least 48 hours, and one seasickness bag for each person.
- Instructions on how to survive (Survival booklet)
- Instructions on immediate action
- TPA is sufficient for 10% of the number of persons or two, whichever is greater
- Marking shall be SOLAS ‘A’ Pack
- 6 Hand Flares
- 4 Rocket Parachute Flares
- 2 Buoyant Smoke Signals
The Ultimate Guide To Deck Machinery Procedures and Operations
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
Markings on an inflatable Liferaft
Important markings provided on an inflatable type of liferaft are:
- Maker’s name and trademark
- Serial Number
- Date of manufacture
- Name of approving authority
- Name and place of the last service
- Number of persons permitted
Launching of a liferaft when the ship sinks and HRU activates (Auto)
A general overview of the launching procedure of a liferaft when the ship sinks are:
- When the ship sinks up to 4 metres, the water pressure will activate a sharp knife in the HRU
- It will cut the securing rope around the container/canister of the raft, and the raft will float free
- As the ship sinks further, the painter line will stretch, and it will inflate the life raft
- Due to the increase in buoyant pressure, the weak link will break at around 2.2 kN +/- 0.4, and the raft will be on the surface.
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 its 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.
If the life raft inflates and is upside down, the raft has a righting strap capable of stabilizing it. Climb onto the CO2 cylinder and pull it in the same direction as the wind to do so.
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
Frequently Asked Questions
1. What is a life raft?
A life raft is a small, inflatable, rigid boat carried onboard a ship. It can be used for evacuation in case of an emergency or disaster on the vessel. It is essential safety equipment.
2. What all things do a life raft carry?
A life raft must have all the basic items needed for survival at sea. It should have some rations, pyrotechnics and life jackets. Some vessels have a davit launching system which enables the crew to inflate the raft and board it on the deck instead of lowering it first into seawater.
3. How many types of life rafts are there?
There are three kinds of life rafts, namely offshore, coastal and ocean-going life rafts. Platforms are designed to keep survivors out of the water while they wait to be rescued.
4. What is the difference between a lifeboat and a liferaft?
Lifeboats may or may not be inflatable. They can have fibreglass or wooden hull as well. However, liferafts are strictly inflatable and come with auto-inflation devices like mechanical pumps or Co2 canisters.
5. How many persons can a life raft hold?
A life raft comes in different sizes and is made of sturdy material like neoprene or polyurethane fabric. Usually, they can accommodate at least six people.
You might also like to read
- Types of Lifeboat Release Mechanisms And Solas Requirements For Lifeboats
- Measures To Stop Accidents On Lifeboats
- Survival at Sea: How to Safely Beach a Life Boat?
- Enclosed Lifeboat Release Accidents: Reasons And Prevention
- Types of Life-Saving Equipment Onboard Ships
- Concept: A Life Raft that Makes Drinking Water from Seawater
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Shilavadra Bhattacharjee is a shipbroker with a background in commercial operations after having sailed onboard as a Third Officer. His interests primarily lie in the energy sector, books and travelling.