Which type of rolling is considered dangerous?

Synchronous rolling is considered particularly dangerous due to the way it occurs in certain conditions, often linked to the ship's natural rolling period aligning with wave periods in a seaway. When a ship is in synch with the waves, it may roll excessively as it meets the waves at optimum intervals, leading to increased heeling angles. This can result in a loss of stability, and in extreme cases, can cause capsizing or other dangerous situations.

This phenomenon often exacerbates existing issues with stability, as the forces acting upon the vessel can become more significant when the rolling frequency matches the environmental conditions. Understanding synchronous rolling is crucial for safe navigation, especially in rough seas where wave patterns and ship behavior can be closely related.

Periodic rolling usually refers to a consistent rolling pattern that a ship may experience but is not as dangerous as synchronous rolling. Random rolling implies a more erratic pattern that is generally less predictable but doesn't present the same immediate correlation with wave patterns as synchronous rolling does. Combined rolling, which may involve elements of both periodic and random behaviors, can also be problematic but typically does not match the specific hazards associated with the alignment of wave and ship rolls that synchronous rolling embodies.