HYDROPLANE • DICTIONARY ONE.COM • Definition of Hydroplane

... was 40 knots, or nearly a mile a minute. They were driven by twin screws coupled to twin engines of 350 h.p. each—working at 1350 revolutions per minute. Being of very shallow draught, some 26 inches, these little vessels could skim, hydroplane fashion, over any ordinary mine-field, and a torpedo fired at them would merely pass under their keel. The risk of destruction from shell-fire was also reduced to a minimum by their small size and great speed. Their principal enemies ...

— Submarine Warfare of To-day • Charles W. Domville-Fife