What happens to the righting arm when the vessel's center of gravity rises?

When the center of gravity of a vessel rises, the righting arm, which is the horizontal distance between the center of buoyancy and the center of gravity, typically decreases. This reduction in the righting arm affects the vessel's stability because the righting moment, which is the force that acts to return a tilted vessel to an upright position, is directly related to the size of the righting arm.

As the center of gravity moves higher, the weight of the vessel creates a greater tendency for the vessel to heel, and the restoring force becomes less effective. Therefore, a higher center of gravity results in a smaller righting arm, leading to reduced stability. The relationship between center of gravity and righting arm is crucial in stability calculations, especially in ensuring that vessels operate safely within their design limits.