construction of inflatable liferafts
the main buoyancy chamber shall be divided into not less than two separate compartments, each inflated through a nonreturn inflation valve on each compartment. The buoyancy chambers shall be so arranged that, in the event of any one of the compartment being damaged or failing to inflate, the intact compartments shall be able to support, with positive freeboard over the liferaft's entire periphery, the number of person which the liferaft is permitted to accommodate, each having a mass of 75 Kg and seated in their normal positions.
The floor of the liferaft shall be waterproof and shall be capable of being sufficiently insulated against cold either
1. by means of one or more compartments that the occupants can inflate automatically and can be deflated and re-inflated by occupants; or
2. by other equally efficient means not dependent on inflation.
4.2.2.3 The liferaft shall be capable of being inflated by one person. The liferaft shall be inflated with a non-toxin gas. The inflation system, including any relief valves installed in compliance with paragraph 4.2.2.4, shall comply with the requirements of an international standard acceptable to the Organization. Inflation shall be completed within a period of 1 min at an ambient temperature of between 18c and 20c and within a period of 3 min at an ambient temperature of -30c. After inflation, the liferaft shall maintain its form when loaded with its full complements of person and equipment.
4.2.2.4 Each inflatable compartments shall be capable of withstanding a pressure equal to at least three times the working pressure and shall be prevented from reaching a pressure exceeding twice a working pressure either by means of relief valves or by a limited gas supply. Means shall be provided for fitting the topping-up pump or bellows required by paragraph 4.2.9.1.2 so that the working pressure can be maintained.
4.2.3 carrying capacity of inflatable liferafts
the number of persons which a liferaft shall be permitted to accommodate shall be equal to the lesser of
1.The greatest whole number obtained by dividing by 0.096 the volume, measured in cubic meters, of the main buoyancy tubes(which for this purpose shall include neither the arches nor the thwarts, if fitted) when inflated ; or
2. The greatest whole number obtained by dividing by 0.372 the inner horizontal cross-sectional area of the liferaft measured in square meters (Which for the purpose may include the thwart or thwarts, if fitted) measured to the innermost edge of the buoyancy tubes ; or
3. The number of persons having an average mass of 75 Kg, all wearing either immersion suits and lifejackets or, in the case of davit-launched liferafts, lifejackets , that can be seated with sufficient comfort and headroom without interfering with the operation of any of the liferaft's equipment.
4.2.4 Access into inflatable liferafts
4.2.4.1 At least one entrance shall be fitting with a boarding ramp, capable of supporting a person weighing 100 kg sitting or kneeling and not holding onto any other part of the liferaft . to enable persons to board the liferaft from the sea . The boarding ramp shall beso arranged as to prevent significant deflation of the liferaft if the ramp is damaged. In the case of a davit-launched liferaft having more than one entrance , the boarding ramp shall be fitted at the entrance opposite the bowsing lines and embarkation facilities.
4.2.4.2 Entrances not provided with a boarding ramp shall have a boarding ladder , the lowest step of which shall be situated not less than 0.4 m below the liferaft's light waterline.
4.2.4.3 There shall be means inside the liferaft to assist persons to pull themselves into the liferaft from the ladder
4.2.5 Stability of inflatable liferafts
4.2.51 Every inflatable liferaft shall be so constructed that , when fully inflated and floating with the canopy uppermost, it is stable in a seaway.
4252 The stability of the liferaft when in the inverted position shall be such that it can be righted in a seaway and in calm water by one person.
4253 The stability of the liferaft when loaded with is full complement of persons and equipment shall be such that it can be towed at speeds of up to 3 knots in clam water.
4254 Theliferaft shall be fitted with water pockets complying with the following requirements
1. The water pockets shall be of a highly visible colour