Ship In A Storm

Boats and ships are kept on (or slightly above) the water in three ways:
- For most vessels, known as displacement vessels, the vessel's weight is offset by that of the water displaced by the hull.
- For planing ships and boats, such as the hydrofoil, the lift developed by the movement of the foil through the water increases with the vessel's speed, until the vessel is foilborne.
- For non-displacement craft such as hovercraft and air-cushion vehicles, the vessel is suspended over the water by a cushion of high-pressure air it projects downwards against the surface of the water.