Aperfeicoada character of helices thrusters of vessels

摘要

Propeller arrangement for marine vessels. A small supplemental and independently drivable propeller is mounted for swivelling in a horizontal plane and is preferably positioned in fore-and-aft alignment with at least one main propeller and slightly above same. Preferably the supplemental propeller is positioned ahead of such main propeller a distance equal to at least three-quarters of the diameter of the blade tip circle of the supplemental propeller. The blade tip circle of the supplemental propeller, when projected onto a common transverse plane may lie wholly within the correspondingly projected blade tip circle of the main propeller or it may extend partially out therefrom. The arrangement is adaptable to a variety of specific propeller arrangements including offsetting or angularly positioning the thrust line of the main propeller to counteract the turning moment of propeller torque and is further adaptable for use with single or multiple screw vessels. The supplemental propeller is adaptable primarily for harbor maneuvering and is of design appropriate to low speed operation as distinguished from the higher speed operation of the main propeller. In addition the supplemental propeller can increase the mean operation speed.