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Feb 10, 2025
A totally enclosed lifeboat has a fixed rigid roof on its upper part. For the convenience of crew members' entry and exit, the totally enclosed lifeboat is equipped with a cover that can be opened and closed from both inside and outside. When closed, this cover ensures the watertightness of the lifeboat and provides good thermal insulation. Because of the excellent safety features of this type of boat, which protect the crew from wind, rain, waves, and cold, totally enclosed lifeboats are now widely equipped on ships.
Enclosure Cover
Every totally enclosed lifeboat should have a rigid cover that entirely encloses the lifeboat. The arrangement of the cover should:
Provide shelter for the occupants.
Include a hatch that allows entry into the lifeboat, which can be closed to make the lifeboat watertight.
For lifeboats other than free-fall lifeboats, the hatch location should allow launching and recovery operations to be completed without any occupant having to leave the enclosure cover.
The hatch cover should be operable from both inside and outside and should have facilities to secure it firmly in the open position.
Besides the free-fall lifeboats, there should also be means to row the lifeboat.
When the totally enclosed lifeboat is in an upside-down position, with the hatch closed and no significant water leakage, it should support the entire mass of the lifeboat, including all accessories, machinery, and all occupants.
Windows or translucent panels should be installed on both sides of the cover to allow sufficient sunlight to enter the lifeboat with the hatch closed, eliminating the need for artificial lighting.
The exterior of the cover should be a bright, easily visible color, while the interior color should not make occupants feel uncomfortable.
Handrails should be provided for personnel to use outside the lifeboat and to assist in boarding and disembarking.
Occupants should be able to reach their seats from the entry point without having to cross transverse seats or other obstacles.
When the lifeboat engine is running and the cover is closed, the atmospheric pressure inside the totally enclosed lifeboat should not be lower or higher than 20 hPa compared to the external atmospheric pressure.
Capsizing and Righting
Except for free-fall lifeboats, each designated seat should have a safety belt. The safety belt should be designed to securely hold a person weighing 100 kg in place when the totally enclosed lifeboat is in an upside-down position. Each set of safety belts on the seats should be of a color distinctly different from the adjacent seat belts.
The stability of the lifeboat should allow it to right itself when fully or partially loaded with occupants and accessories, with all hatches and openings watertightly closed, and all occupants securely fastened with safety belts.
If the lifeboat has an underwater hull hole, it should support all occupants and accessories, assuming no flotation materials are missing and no other damage has occurred. In the event of capsizing, the lifeboat should automatically provide a position for occupants to escape from the water. When the lifeboat is in a stable submerged state, the water level inside the lifeboat, measured along the seat backs, should not exceed 500mm above the seat boards at any occupant's seating position.
All engine exhaust pipes, air pipes, and other openings should be designed to prevent seawater from entering the engine when the totally enclosed lifeboat capsizes and rights itself.
Acceleration Protection
Besides the structure and fenders installed on free-fall lifeboats, totally enclosed lifeboats should ensure that when loaded to full rated occupants and accessories, they can protect against harmful acceleration impacts resulting from collisions with the ship's side at a collision speed of no less than 3.5 m/s.
