Question 26 LB01 - Lifeboat Operator

The Correct Answer is C ### Why Option C ("Gravity davit") is correct: Gravity davits are designed to deploy a lifeboat primarily using the force of gravity. Due to the high speeds potentially involved in a gravity-fed launch, and the critical need to stop the boat at the embarkation deck and/or the final launch position, all modern gravity davits are equipped with a **limit switch**. This limit switch serves several safety functions, often tied to an electrical control system: 1. **Safety Interlock:** It prevents unauthorized or accidental lowering past a certain point. 2. **Automatic Cut-Off:** It automatically stops the winch motor and/or braking system when the lifeboat reaches its final stowage position (upper limit) or a preset lower limit (like the deck level during recovery), preventing over-hoisting or over-lowering damage. 3. **Preventing Two-Blocking:** An ultimate limit switch prevents the pulley blocks from being pulled up and contacting the davit arm (two-blocking), which would cause significant structural damage. ### Why the other options are incorrect: * **A) Radial davit:** Radial davits (or pivot davits) are older types of mechanical davits. They are swung out manually using turning bars or permanently fixed cranks. While they use ratchet and pawl systems, they are fundamentally mechanical and generally do not utilize electrical limit switches for operation or safety cut-offs, unlike modern power-operated davits. * **B) Sheath-screw davit:** Sheath-screw davits are another type of mechanical davit that operates by turning a screw mechanism to lower or raise the boat. Like radial davits, their operation is purely mechanical, relying on manual effort and physical brakes. They do not typically incorporate electrical limit switches. * **D) Liferaft cradle:** This option refers to the platform or structure holding a liferaft, not the mechanism used to launch it. The mechanism that launches a liferaft (often a single-arm slewing davit) will have limit switches, but the cradle itself is a passive component and does not contain the switch. Furthermore, while the launching mechanism may be related to a davit system, gravity davits are specifically the class most often associated with heavy lifeboats requiring stringent, electrically controlled stopping mechanisms.