In a recent project, named SEALAB, a novel marine vehicle has been developed. Its main characteristic is the presence of special skid surfaces surfing over rough water. A suspension system controls the vertical motion of the skid, softening the sequential impacts and vibrations induced by the water, similarly to a wheeled vehicle in off-road trials. The hull-skid-suspension set is modelled by prototypical equations. The system undergoes special regimes when the vessel speed at sea is varied. In particular, for some combinations of the forward speed and sea-state, the skid still maintains the contact with the water. In other navigation conditions the skid indeed jumps out the water with a complete different average transmitted force and vibration characteristics of  the hull. This paper presents a theory that outlines these phenomena identifying conditions that lead to the jumping skid condition. It appears that the global picture of the vessel response can be represented as follows: below a certain sea-state threshold (in terms of wind speed) and whatever the vessel speed, the jumping condition never appears; if this threshold is passed, then two vessel critical speeds emerge: the lower critical speed, beyond which the skid jumps out the water and an intermittent water-skid contact takes place, and a higher critical speed, passed the which, the jumping ceases and again a continuous water-skid contact stabilizes again.

Numerical simulation confirms this picture, named skid fluttering.