What are the three major types of ship stability?

The three major types of ship stability are initial stability, dynamic stability, and ultimate stability.

Initial stability refers to the ship's ability to resist tilting from an upright position when a small angle of heel is created, often measured by the metacentric height (GM). This initial stability is crucial for the performance of a vessel in calm water and plays a significant role in determining how a vessel responds to small disturbances.

Dynamic stability encompasses the behavior of a vessel when it has been heeled over to a significant angle. It includes the factors that influence how a ship returns to an upright position after being knocked over by waves or other forces. Dynamic stability is important for understanding how well a vessel can recover from capsizing scenarios, which is critical for safety.

Ultimate stability pertains to the maximum angle of heel at which the vessel can remain upright before capsizing. This concept is vital when assessing a ship's overall stability profile during extreme conditions or significant heeling, as it defines the limits of safe operation.

Focusing on these three types allows for a comprehensive understanding of a ship's stability under various conditions, illustrating their importance for vessel design, safety regulations, and effective seamanship.