Question 54 GLI04 - Mate of LT 500-1600 GRT

The Correct Answer is D. **Why option D ("Water under vessel must be deep enough to prevent grounding") is correct:** A stability test (often involving inclining experiments or lightship surveys) is a critical procedure used to accurately determine the vessel's center of gravity (KG) and lightship displacement. For the results to be valid and accurate, the vessel must be able to rotate freely about its longitudinal axis (roll) and settle naturally. If the vessel grounds, even lightly, its motion is restricted, external forces are introduced, and the apparent center of rotation is altered. This completely invalidates the measurements taken during the test. Therefore, ensuring adequate water depth to prevent grounding throughout the entire procedure is a fundamental requirement. **Why each of the other options is incorrect:** * **A) Each tank must be partially full to show it does not leak:** During stability tests, the condition of the vessel's tanks is strictly controlled. Tanks must either be pressed full (no free surface effect) or completely empty and dry (no free surface effect). A partially full tank creates a "free surface effect," which significantly reduces stability (raises the effective KG) and makes accurate calculation of the vessel's true stability parameters impossible. Showing leaks is not the purpose of a stability test, and partially full tanks are strictly prohibited. * **B) All dunnage, tools, and extraneous items are secured:** While good housekeeping and securing loose items are standard safe operational practices, for an *accurate* stability test, all moveable items (dunnage, tools, spare gear, stores, etc.) must typically be inventoried, weighed, and either removed from the vessel or relocated to a measured position (usually the center line) to minimize their effect on the calculations or eliminate unwanted shifting during the test. Simply securing them in place does not meet the necessary standard of control for a stability test. * **C) The vessel must be moored snugly:** The vessel must be moored, but the mooring lines must be kept slack ("breast lines slack") to allow the vessel to roll and trim freely without external constraint. Snug mooring lines would inhibit the vessel's natural movements, introduce unpredictable external forces, and invalidate the inclining experiment results. The goal is to simulate free-floating conditions.