Submarine

Submarine A ship capable of operating underwater. The first prototype modern submarine did not appear until 1898. Powered by electric motors underwater and a petrol engine on the surface, it was designed by J.P. Holland. Later submarines had a diesel engine for use on the surface and to charge the batteries. In 1954 the Americans launched the first nuclear submarines, Nautilus. Nuclear submarines have a boiler to raise steam and steam turbines for propulsion. Submarines dive and surface by letting water into and expelling it (with compressed air) out of ballast tanks.

Submersible The name usually given to small submarine craft used, for example, to make underwater surveys and to assist divers. They may be equipped with mechanical arms and diving chambers.