What happens during parametric roll?

During parametric roll, the phenomenon occurs when the frequency of the waves encountered by the ship coincides with the ship's natural roll frequency. As the ship moves through a regularly spaced wave pattern, it can begin to resonate with the waves, leading to an amplification of its rolling motion. This can result in significant and abrupt changes in the ship's heeling angle.

When the frequency of the waves matches the ship’s natural roll frequency, the ship can roll more significantly than it would under normal conditions, potentially leading to hazardous situations. This resonance can cause the ship to roll to extreme angles and could even lead to capsizing if not adequately managed.

In contrast, the other choices describe scenarios that do not accurately reflect the conditions during parametric roll. The ship experiencing constant stability, becoming completely submerged, or experiencing no significant movement does not align with the dynamic and potentially dangerous nature of parametric roll. Understanding this phenomenon is critical for safety in maritime operations, as it highlights the importance of ship design and operational procedures in relation to wave conditions.