Paul Kamen and Douglas Railton, Arneson Marine, Inc.
Society of Naval Architects and Marine Engineers
Northern California Section
Propulsion systems involving partially submerged propellers are playing an increasingly important role in the design of high speed small craft. The primary advantages of surface propulsion are examined. These include: unrestricted propeller diameter, suppression of cavitation, elimination of external shaft and strut drag, reduced shaft angle, and shallow draft. In the case of fully articulated systems, variable propeller submergence can extend the efficient operating range of the system in a manner somewhat analogous to controllable pitch. Rudder drag is also eliminated, maneuverability is improved, and operation at extreme shallow draft becomes feasible. Some of these advantages apply to relatively heavy, low-speed vessels with at least equal impact, and new applications of the surface drive in this area are discussed. A number of applications notable for their success, unusual problems, or novel design features are presented in an accompanying video. A disk containing Arneson Marine's planing hull resistance and propulsion program is distributed along with the paper.