Question 65 RVR05 - Master of LT 100 GRT

The Correct Answer is B **Explanation for Option B (Correct):** The problem states that the vessel has developed a list because the center of gravity (G) has risen above the transverse metacenter (M), meaning the vessel has negative initial stability (GM is negative). To correct this situation, the priority is to lower the center of gravity (G) to restore positive stability (i.e., ensure G is below M, resulting in a positive GM). Adding weight low down, specifically in the lower holds or double bottoms along the centerline, achieves this goal efficiently. Adding weight on the centerline minimizes further listing caused by the new weight while maximizing the reduction of KG (height of the center of gravity), thus restoring positive stability and allowing the vessel to naturally right itself (or be easily corrected). **Explanation of Incorrect Options:** **A) Shift weight to the centerline:** Shifting existing weight (especially high weight) inwards will lower the center of gravity (G), which improves stability. However, shifting weight alone does not correct the list caused by negative GM as effectively as adding low weight. More importantly, if the vessel already has negative stability, shifting existing weight cannot overcome large negative GM values and may not fully resolve the list, whereas adding low weight is the most direct and powerful method to restore $GM$ quickly and safely. **C) Shift weight to the high side:** Shifting weight transversely (especially to the high side) changes the position of the center of gravity (G) horizontally ($G$ moves to $G_1$). While this action creates a righting moment that attempts to reduce the list, it does absolutely nothing to improve the vessel’s underlying stability (it does not change KG or GM). If the vessel has negative $GM$, shifting weight might momentarily reduce the angle, but the vessel remains inherently unstable and prone to capsizing. This is a highly dangerous action. **D) Remove weight from the lower holds or double bottoms:** Removing weight from low down causes the center of gravity (G) to rise (KG increases). Since the vessel is already experiencing instability due to KG being too high, removing low weight would further decrease the vessel's stability (make $GM$ more negative) and exacerbate the list, leading to an immediate and high risk of capsizing. This is the opposite of the prudent action required.