hydroplane -
The wing of a submarine, used to help control depth.
Verb
hydroplane -
To skim the surface of a body of water while moving at high speed.
Wikipedia
A hydroplane (or hydro, or thunderboat) is a colloquial term for a Hydrofoil used exclusively for racing. A key aspect of hydroplanes is that they use the water they're on for lift rather than bouyancy, as well as for propulsion and steering: when travelling at high speed water is forced downwards by the bottom of the boat's hull. The water therefore exerts an equal and opposite force upwards, lifting the vast majority of the hull out of the water.
