whipping

"Whipping" is a hull vibration that occurs when a ship's bow emerges from the water and then re-enters it with a heavy impact, often in rough weather. This dynamic event excites a two-noded frequency in the hull, generating stresses comparable to those from static wave-bending. It can also cause high localized stresses at the point of impact. While slamming and whipping can be mitigated by reducing speed or altering course, another type of wave-excited vibration, "springing," arises from resonance between wave frequencies and the hull's natural vibratory frequencies, making it harder to avoid.1