What is the rolling period of a vessel?

• A. The time in seconds required for one complete roll, such as from port to starboard and back to port
• B. The distance rolled per second
• C. The time for a half-roll
• D. The duration of the ship's entire voyage

Answer: (A)

Rolling period is the time it takes for the vessel to complete one full roll, a complete side-to-side oscillation. In other words, it’s the duration, in seconds, from a given heel angle back to the same heel angle after going from port to starboard and returning. This distinguishes a full cycle from a half-roll, which would be the time to move from one extreme to the opposite extreme and is only half of the full cycle. It’s not a measure of distance rolled per second, nor related to the ship’s entire voyage.