A marine craft having a propeller tunnel in which the sidewalls of the tunnel are essentially parallel and vertical and mate with a descending upper surface of the tunnel which optionally can be divided into a transom plate portion, engine plate portion, and bottom plate portion. The bottom plate portion mates with the bottom of the boat hull in a sharp line intersection. A surfacing propeller and associated drive shaft is mounted in the tunnel with a rudder positioned aft of the surfacing propeller. Baffles are provided on the lateral sides of the tunnel and terminate in a forward portion aft of the bottom plate portion of the tunnel. Optionally the exhaust can be vented onto the bottom plate portion of the tunnel to augment the flow of air. The method of the invention is directed to forcing the flow of air inside a surfacing propeller tunnel on a boat to the end that baffles provided on the lateral side are fed by air from the transom portion of the baffle and induced by the forward motion of the boat as well as the pneumatic effect of the surfacing propeller portion which is not in the water to force the air to go into the tunnel portion and thereby minimize any negative pressure build-up which would otherwise occur absent of venting. In addition the method contemplates augmenting the pressure within the tunnel by directing the exhaust to a forward portion of the tunnel.

Propeller tunnel baffle and method

A marine vessel having a propeller tunnel possessing a flow-favorable cross-sectional configuration following the flow lines of the water. Within the propeller tunnel there is mounted a propeller essentially throughout one-half of its circumference. An adjustable control plate can be extended in order to detach the flow of the water from the surface of the tunnel during rapid travel of the marine vessel. In this case, the propeller functions as a partially immersed propeller at a high rotational speed. There can be provided a control device which adjusts the control plate as a function of the rotational speed range within which the propeller operates. The propeller can be an adjustable propeller conjointly adjustable with the control plate.

Marine vessel with propeller

A novel bottom configuration for a V-type planing hull which consists of a V-shaped section which extends from the bow to a shoulder located aft of amidships, and a section aft of the shoulder consisting of a partial continuation of the V-sidewalls, joined by a generally horizontal bottom wall which extends to the transom.

Planing boat hull

An improved method for raising a propeller up into the hull of a marine water craft for the purpose of reducing the likelihood of underwater impact and improving shallow water operation without encountering the high efficiency losses normally associated with shallow draft drive systems or water jets. It utilizes a unique tunnel which is open bottomed and extends longitudinally in the running surface of the hull. The lead in to the tunnel, which is termed the “chute” forms the entry to a deeper portion of the tunnel located further aft. A super-cavitating propeller is positioned in the aft tunnel section. The propeller is raised vertically into the tunnel such that the propeller blade tips can be above, below or flush with the running surface of the hull but the prop shaft is always above the running surface of the hull. The invention relates to the longitudinal position of the chute with respect to the propeller, the general shape of the chute and its normal method of operation.

Method for reducing vessel draft

The instant invention is directed toward a marine craft having a semi-enclosed surfacing type propeller in a tunnel that draws air through the specific areas located and shaped to enhance performance and compensate for prime mover torque and horsepower characteristics. The invention consists of these air induction features with description of their relationship to craft performance and operating characteristics. This invention also relates certain structures and configuration of these elements, as to enhanced control of said marine craft. The control of these elements having no moving parts or operator interface. Its sequencing is established by the hull movement and the water around it.

Semi-enclosed surfacing propeller driver system including air induction

A propulsion system for high speed planing hulls, employing a tunnel-mounted propeller of the supercavitating type in conjunction with means for causing the propeller to operate partly submerged at planing speeds and, aided by the tunnel, to operate fully-submerged with great effectiveness at low hull speed to enable the propeller to develop ample thrust to drive the craft up to and into planing speed.

P Sherman

Papers

Marine propulsion system