Liferafts on Ships: Essential Life-Saving Devices Explained

Liferafts on Ships: In addition to lifeboats, every seagoing passenger or cargo ship is equipped with life rafts as a life-saving device.

Launching a liferaft is far simpler than launching a lifeboat. Since the life rafts are equipped with an auto-inflating mechanism, it is possible to evacuate the ship during an emergency without having to manually launch any of them.

According to the size and type of the ship, SOLAS Chapter III provides all the information regarding the types and quantity of life rafts that must be carried.

Where are Life Rafts on Ships located?

(Credit: Nautilus Shipping)

Usually found on the muster station, the aft of the ship, and the port and starboard sides close to the lifeboat, are the locations of life rafts. The size of the ship typically determines the location.

In the event of an emergency, life rafts are inflated by a high-pressure gas and kept in a fiberglass container.

The raft container and ship are coupled to a hydrostatic release unit (HRU), which releases the raft even after the vessel submerges in water.

The container is emblazoned with the raft’s specifications, including its capacity, date of manufacture, date of servicing, firm name, and launch process, all presented in a visually appealing manner for effortless comprehension.

The raft is already equipped with all the necessities for survival, such as food, fireworks, life jackets, etc.

A davit launching mechanism, which some ships have, enables the crew to inflate and board the raft on the deck without having to worry about seawater getting inside.

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Crucial Conditions for Life Rafts

lifeboat
(Credit: Merchantnavyguide)
  • Whenever a liferaft is provided on a ship, its painter should be permanently attached to the vessel.
  • To ensure that each liferaft or group of liferafts floats freely, they must be stowed in a float-free arrangement that meets the requirements. When a ship sinks, an inflatable raft should automatically inflate.
  • It is recommended that liferafts be stowed in a manner that allows them to be manually released from the securing arrangements one at a time.
  • Liferafts launched from davits should be stowed within reach of the lifting hooks, unless some transfer mechanism is used that is not rendered inoperable by ship motion or electrical failure.
  • For throw-overboard launching, liferafts should be stowed in a way that makes them easily transferrable from one side of the ship to the other.

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

The automatic release hooks on davit-launched liferafts should be maintained in accordance with the onboard maintenance instructions

Essential Requirements for Liferafts and Carrying Capacity

Liferaft types

The liferaft of any ship must comply with the requirements of SOLAS. The following are some important points regarding liferafts:

  • Lift rafts should be capable of withstanding 30 days of exposure while afloat in all types of sea conditions

  • A life raft and all its equipment will function satisfactorily when dropped from a height of 18 metres into the water.

  • With and without the canopy erected, the floating life raft should be able to withstand repeated jumps from at least 4.5 metres above its floor.

  • With its complete equipment, complement of persons, and one anchor streaming, it can be towed at a speed of three knots.

  • Two layers of material separated by an air gap provide insulation and protection from heat and cold

  • The interior should have a non-discomforting color scheme.

  • It must provide sufficient air for the occupants at all times, even if the entrance is closed

  • At least one viewing port must be provided

  • A rainwater collection system will be provided

  • The survival craft radar transponder (SART) shall be mounted at a height of at least 1 meter above sea level using a tool provided by the manufacturer

  • In all parts of the canopy, there should be sufficient headroom for the sitting occupants

  • A minimum carrying capacity of six persons is required

  • Its container and equipment should not weigh more than 185 kilograms

  • An efficient painter shall be mounted on the life raft of a length equal to a 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.

  • An electrically controlled lamp shall be installed on top of the canopy. The lamp shall be white, and it should operate for at least 12 hours with a luminous intensity of at least 4.3 candelas.

  • For the 12 hours that the flashlight burns, it must flash at a rate of not less than 50 flashes per minute and not more than 70 flashes per minute

  • The life raft must be equipped with a manually controlled lamp that is capable of operating continuously for at least 12 hours

  • The liferaft should be able to withstand a lateral impact against the ship side at an impact velocity not less than 3.5 metres per second when loaded with a full complement of people and equipment, as well as drop into the water without damage from a height of not less than 3 metres.

  • CO2 inflates with a small amount of N2, which acts as an anti-freezing agent. Furthermore, CO2 is non-flammable and weighs more than air, which adds buoyancy to the raft. As CO2 has a freezing point of -78 degrees, it can be used to inflate life rafts at shallow temperatures

  • Location on a ship:
    – Forward
    – 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)

Liferaft safety features

A liferaft is equipped with several safety features, including:

  • Relief valve for pressure

  • Pocket stabilization

  • Heat and cold-proof canopy with two layers

Important liferaft equipment

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 a 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

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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)

The following is a general overview of the procedure for launching a liferaft when a ship sinks:

  • If the ship sinks up to four metres, the water pressure will trigger a sharp knife in the HRU

  • If the securing rope is cut around the container/canister of the raft, the raft will be able to float on its own

  • When the ship sinks further, the painter line stretches and inflates the life raft

  • The weak link will break at around 2.2 kN +/- 0.4 as a result of the increase in buoyant pressure.

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