SQA Chief Mate Stability Theory Practice Test 2026 - Complete Exam Prep

When the center of gravity of a vessel is raised, the stability decreases, making the vessel more susceptible to heeling. This occurs because stability in floating vessels is reliant on the relationship between the center of gravity (KG) and the center of buoyancy (KB).

When the center of gravity is elevated, the metacentric height (GM) is effectively reduced because the metacenter (M) does not move as significantly as the center of gravity. A lower GM indicates weaker stability; as a result, the vessel will have a diminished righting moment when it heels. Consequently, the vessel becomes more prone to tilting or rolling over, especially in the presence of external forces like wind or waves.

This fundamental principle is vital for the safety and performance of any vessel, and it's essential for mariners to understand how changes in stability can impact a vessel's ability to resist heeling and maintain an upright position.