A liferaft is a float that helps keep people alive after they have left a ship in distress. Its design must be such as to withstand the influence of the environment afloat for at least 30 days under any hydrometeorological conditions. Rafts are produced a capacity of at least 6 and usually up to 35 (in passenger ships can meet rafts up to 150 people).
The number of rafts is calculated so that the total capacity of the liferafts on each side is sufficient to accommodate 150% of the total number of people on board.
Additional liferaft on board.
On vessels where the distance from the bow or stern to the nearest raft is more than 100 m, an additional raft must be installed.
At least 2 lifejackets and 2 immersion suits must be kept nearby, and there must also be landing gear on each side (on high-sided vessels – boarding ramps, on low-sided vessels – rescue pendants with musings.
According to the method of delivery to the water, liferafts are divided into mechanically launched (with the help of davits) and dropped. Launch rafts are mainly installed on passenger ships, since boarding takes place at deck level, which is a great advantage when rescuing passengers who may be in a wide variety of physical and mental conditions.
The main distribution, due to their compactness, received inflatable rafts.
The main elements of the liferaft are:
– buoyancy-camera (provides buoyancy of the raft);
– bottom – a waterproof element that provides insulation from cold water;
– tent – a waterproof element that insulates the space under the tent from heat and cold.
The buoyancy chamber of an inflatable raft consists of at least two independent compartments, so that if one compartment is damaged, the remaining compartments can provide a positive freeboard and keep the required number of people and supplies afloat. Usually, the compartments are arranged in rings one above the other, which allows not only to provide sufficient buoyancy, but also to save the area for accommodating people in case of damage to one compartment.
To maintain the working pressure in the compartments, special valves are installed for manual priming with a pump.
The problem of thermal insulation under the awning is usually solved by installing an awning consisting of two layers of waterproof material with an air gap.
The outer color of the awning is specially made orange.
For the installation of an awning in inflatable rafts, arch-type supports are made, which are inflated automatically together with the buoyancy chamber.
The height of the awning is made so that a person can sit in any part of the raft under the awning.