Write reference to gravity life boat davits; state the purpose of the following (20)
(a) Centrifugal brake.
(b) Dead man's handle.
(c) Davit limit switch.
Write reference to gravity life boat davits; state the purpose of the following (20)
(a) Centrifugal brake.
(b) Dead man's handle.
(c) Davit limit switch.
Structured for DG Shipping MEO Class II examination scoring criteria.
The centrifugal brake is a safety device that automatically regulates the lowering speed of the lifeboat. According to SOLAS (Safety of Life at Sea) regulations, the lowering speed must not exceed 36 meters per minute. The brake activates automatically when the rotational speed of the winch drum reaches a specific limit, creating a braking force that prevents the lifeboat from accelerating beyond the safe speed.
The dead man's handle, also known as a handbrake, is a control mechanism that keeps the brake continuously applied to the winch drum under normal conditions. It's designed with a counterweight that holds the brake on, preventing the lifeboat from being inadvertently released. To lower the lifeboat, an operator must actively lift the handle against the counterweight, releasing the brake and allowing the lifeboat to descend. This design ensures that the brake is always engaged unless a person is actively controlling the lowering process.
The davit limit switch is an electrical safety switch that prevents the lifeboat from being hoisted too high. As the lifeboat is being recovered, the switch is automatically triggered when it reaches the maximum safe hoisting position. This immediately cuts off power to the electric motor, stopping the hoisting process and preventing damage to the davit structure or the lifeboat itself.