What are the two principal types of stability?

• A. Longitudinal and Transverse
• B. Vertical and Horizontal
• C. Pitch and Roll
• D. Static and Dynamic

Answer: (A)

Two main directions describe how a boat can tilt and how its stability is evaluated: longitudinal stability and transverse stability.

Longitudinal stability deals with pitching—front to back tilting of the bow up or stern up. It governs how the boat holds its fore-and-aft trim when waves, wind, or weight distribution push the bow up or down.

Transverse stability deals with rolling—side to side tilting of the vessel. It governs how the boat resists tipping to one side when a wave or wind pushes on the beam, which is crucial for preventing capsizing.

The other options describe motions (pitch and roll), dimensions (vertical/horizontal), or states of condition (static/dynamic), rather than the two principal directions in which stability is assessed.