What happens to KN values in relation to trim when a vessel is rolled?

The selection of "B" as the correct answer is based on the concept of how trim influences the stability characteristics of a vessel during a roll. When a vessel is trimmed by the bow, the center of buoyancy moves forward, and this can result in a decrease in the righting arm (GZ) due to the changing geometry of the underwater hull, especially when the vessel is inclined. Conversely, trimming by the stern can increase the righting arm because of the vessel's shape and the positioning of the centers of gravity and buoyancy. Thus, this type of trim can lead to more favorable stability characteristics during rolling.

Understanding how trim interacts with stability is crucial for safe vessel operation. A vessel that is trimmed by the stern may experience enhanced dynamic stability, since the movement of the center of buoyancy can work in favor of creating greater leverage (or righting moment) against inclinations, especially in rolling conditions. Therefore, recognizing that stern trim can provide a more advantageous stability condition is vital for maritime professionals in ensuring proper vessel handling and safety.

This understanding is important in operational contexts and can influence decisions regarding loading practices and ballast, aiming to maintain favorable stability throughout the operation of the vessel.