This part of ISO 3715 gives terms and definitions for screw propellers used in the propulsion plants of ships and other vessels (such as mobile offshore drilling units) that are self-propelled or propulsion-assisted. The definitions are valid only for the hydrodynamically effective part of the propeller. No definitions are given for the mechanical construction of the hub. Vocabulary for hydraulically operated controllable-pitch propeller plants is given in ISO 3715-2.