Abstract: A skeg assembly for a marine propulsion unit includes a generally U-shaped saddle that is removably attached to the lower torpedo section of the gearcase of the propulsion unit, and a thin wedge-shaped skeg extends downwardly from the saddle. During planing conditions of the boat, the water line is slightly below the lower torpedo section so that the saddle is out of the water. The side surfaces of the skeg having opposed water intake openings each of which is bordered rearwardly by a laterally projecting shoulder that terminates in a sharp vertical edge and the intake openings are bordered forwardly by a curved surface that connects the side surfaces of the skeg. The water intake openings communicate with a water passage in the skeg which, in turn, communicates with a water passage in the torpedo section so that water can be delivered to the cooling system of the propulsion unit.

Abstract: A propulsion system for a marine drive, which includes a pair of counter-rotating propellers, provides improved acceleration from idle or low speeds. Engine exhaust from an engine which powers the marine drive is conveyed to the water about each of the propellers. The exhaust gases aerate the water about each propeller to reduce drag resistance on each propeller. Several embodiments of the propulsion system are disclosed which convey the exhaust gases to both propellers for this purpose.

Abstract: A stationary screw induction system for improving performance of a watercraft has a cylindrical housing with a first closed end and a second open end. A housing inlet opening is disposed within the housing between the first and second ends. Disposed within the inside of the cylindrical housing is an induction screw which is a helical shaped surface radially disposed about a spine which is coincident with the central axis of the cylindrical housing and forms the central section of the induction screw. The helical shaped surface has a leading edge in contact with the spine and an outside edge in contact with the inner surface of the housing. An induction channel acts to conduct fluid from the surrounding environment into the stationary screw induction system. The induction channel has an induction inlet which acts in fluid communication with the housing inlet opening.

Abstract: A hydrofoil wing structure is disclosed to be employed as an accessory for a marine propulsion device, to be disposed above and mostly aft of the propelling means of such a device, to contour and concentrate the kinetic energy in the hydrodynamic vortex created by the propelling means; to reduce turbulence, vibration and noise by reflecting acoustic energy downwardly from the surface of the water; to increase the efficiency of such a device powered by an electric battery; to improve the steering and maneuverability of the vessel by providing a rudder for the device; and to serve as a guard preventing the propelling means from entanglement in vegetation or its damage from submerged objects, and to similarly shield a sonar transducer or other instrument used in conjunction with the device for finding fish or gauging the depth of the water.

Abstract: An improved fin structure for attachment to the propeller shaft mount of a surface piercing marine outdrive apparatus. The fin structure has one fin member at one side of the mount for the propeller drive shaft of the marine outdrive. The fin member is so situated that it is in a position to destroy any side thrust exerted by the propeller on the water so as to avoid "walking" of the mount on the water and the propeller laterally.

Abstract: An air encircled marine thruster apparatus for a bow or stern thruster includes an outer pipe or duct that surrounds a first pipe carrying a propulsive stream of water to provide an annular blanket of air around the stream. An inner surface of the first pipe is shaped to radially converge at an outlet of the first pipe to form a nozzle. The outer pipe is larger then the first pipe to provide an annular space around the first pipe and propulsive stream exiting the first pipe. A duct leads air into the annular space to form a blanket of air around the propulsive stream, which increases the thrust produced by the propulsive stream.

Abstract: Propulsion unit for marine vessels with a gear or bearing housing (6) in which a propeller shaft (7) with a surface-breaking propeller (8) is carried. In a horizontal plane the propeller shaft forms an angle (.alpha.) to a guide fin (9) so as to create a resultant force (R) of the pressure force (P) of the propeller and the side force (S), with the resultant force being aligned with the longitudinal direction (C.sub.L) when the vessel is travelling straight ahead.

Abstract: An inflatable boat (1) includes at least one inflatable buoyancy tube (2) forming two substantially parallel branches (3) that are united towards the forward end (4). A bottom (5) that is rigid in the transverse direction is held between the two branches (3) of the inflatable tube (2). A transom (6) is provided for supporting an outboard motor assembly. The boat is characterized in that the stern portion of the underside of its bottom (5) supports at least one projecting bulb (7) that is elongate in the longitudinal direction of the boat and that is constituted by a flexible bag which is inflated by a fluid under pressure. This bulb (4) is disposed facing the position occupied by an arm of the motor assembly that plunges into the water and that supports at least one thrust member together with anticavitation plates.

Abstract: A propulsion unit for watercraft that employs a pair of counter-rotating propellers disposed one in front of the other in order to improve the performance upon acceleration, a cavitation effect is generated around at least one of the propellers at least during acceleration. Various ways in which this can be done employing the exhaust gases from the powering internal combustion engine for driving the propellers are illustrated.

Abstract: Apparatus for further improving the efficiency of a propulsion unit having a driveshaft depending from the stern of a boat, while protecting flora and fauna in the water as well as the propulsion unit. A plate member has an upper end adapted to be positioned forward of a driveshaft housing, and to depend downwardly and rearwardly to terminate in a trailing lower end below a propeller. The plate member tapers outwardly along lateral edges from the upper end to the lower end to divert flora and fauna around and under a housing and a propeller attached thereto. A lower portion of the plate member is divided into a plurality of spaced plate-like components defining passageways therebetween to enable water to flow therethrough for more efficient operation of a propeller. At the same time, the forward surfaces of the plate-like components react with passage of water when under way to urge a boat's stern upwardly to a more efficient hull operating position.

Abstract: A nautical propulsion performance enhancer for a propeller of a marine propeller type propulsion system, comprising a facility for twisting and directing a flow of water into the propeller, in such a manner that swirling water will hit the propeller in a direction opposite to rotation of the propeller. A structure is for mounting the twisting and directing facility to the marine propeller type propulsion system adjacent the propeller, in order to overcome unwanted effects of cavitation and porpoising.

Abstract: A marine propeller using the circulation control principle of blowing tantially over a Coanda surface at the trailing edge of each blade to develop high blade lift (thrust). Each blade has internal chambers and two blowing slots so that blowing is controllable for forward and for reverse thrust without reversing rotational direction of the propeller. This propeller is capable of generating much greater thrust and ship speed at lower RPM and noise levels than conventional propellers.

Abstract: A torque balanced propulsor unit for a submersible vehicle of the type having a bow, a stern, a longitudinally extending central section axisymmetric about a longitudinal axis of the vehicle and including therein a maximum diameter of the vehicle, and a tapered aft section axisymmetric about the longitudinal axis is provided. The torque balanced propulsor unit includes a rotor for providing a forward thrust to the vehicle. The rotor includes a central axisymmetric hub and a plurality of circumferentially spaced apart impeller blades extending radially from the central hub. The rotor is rotationally mounted to the tapered aft section of the vehicle. The rotor has a first torque associated therewith. The torque balanced propulsor unit further includes a stator for producing a second torque on the vehicle. The stator is secured to the vehicle at a location aft of the rotor.

Abstract: The present invention relates to an aquatic propulsion system of modular construction. The system includes an electric motor and a gearbox that are removables as a unit. The electric motor and gearbox are housed in a two piece enclosure. A retaining ring threadably engages one of said pieces while engaging a flange on the other piece to secure the two pieces together. Optional struts are attached to the retaining ring that support a shroud around the system's propeller.

Abstract: A planing boat having a stern and a bow includes a hull having a generally flat central bottom surface forming a portion of a pad with the surface tapering from a specified width at the stern towards the bow. Reverse wedge surfaces blended with the central bottom surface at the stern and deadrise surfaces blended with the central bottom surface and intersecting with the reverse wedge surfaces continue forward towards the bow. The rear portion of the flat bottom surface is tipped upwardly towards the stern.

Abstract: A device for permitting an outboard motor boat to operate in shallow water, comprises a first support for securing to a transom of a boat and extending rearwardly therefrom; a keel secured to the first support and extending downwardly therefrom and rearwardly from the transom; a vertically adjustable motor mount for supporting an outboard motor with a propeller housing having a leading surface, the motor mount for positioning the motor in a raised position to permit the boat to operate in shallow water and a lowered position in normal-depth water; and the keel includes a rear edge substantially parallel and adjacent to the leading surface of the propeller housing when the motor mount is in the raised position.

Abstract: Apparatus for improving the efficiency of a propulsion unit having a driveshaft housing depending from the stern of a boat, while protecting swimmers and the propulsion unit. A plate member has an upper end to be positioned forward of a driveshaft housing and to depend arcuately downwardly and rearwardly to terminate in a trailing lower end below a propeller. The plate member tapers outwardly along lateral edges from the upper end to the lower end to divert swimmers around and under a housing and a propeller attached thereto. The plate member reacts to the passage of water when under way to urge the boat's stern upwardly toward a more efficient operating position. The outer corner areas of the upper and lower ends are connected by outwardly curved rods to define a protection zone to protect body parts of swimmers by diverting them outwardly and downwardly under a propeller.

Abstract: A marine drive (10) has two counter-rotating surface operating propellers (12 and 14). The upper end (302) of the leading edge (288) of the skeg (194) is spaced forwardly of the lower end (310) of the trailing edge (306) of the skeg (194) by a horizontal distance greater than the horizontal length of the torpedo (188), for full rudder control. The skeg (194) has a first zone (318) with outer surface profiles (12P-15P) which are continuous and define continuous skeg sidewalls (320, 322) therealong. The skeg (194) has a second zone (324) above the first zone (318) and with outer surface profiles (9P-11P) along horizontal cross-sections, which profiles are discontinuous and define skeg sidewalls with openings (192, 193) therein. The horizontal cross-sections along the second zone (324) have discontinuous gaps (332, 333, 336) therein defining a cored passage (196) within the skeg (194) communicating with the openings (192, 193) in the sidewalls (320, 322).

Abstract: The invention relates to attachments to the anticavitation plate of a boat motor for making and controlling small variations in boat speed below the normal motor idling speed to facilitate trolling for fish. The trolling speed control includes an incrementally adjustable unitary plate mounted for movement between a position fully across the normal paths of the propeller wash, thereby to slow the speed of the boat and to a fully retracted position out of the path of the propeller wash. This invention relates to motorboat low speed control devices.

Abstract: The invention provides an improved SWATH type vessel having pontoons and a stern plane located in a position to influence water flow in the region of the tail cone portions of the pontoons and the propellers to reduce depression of the water adjacent the propellers which would otherwise cause propeller ventilation when the vessel is moving at speed.

Abstract: A low-aspect ratio propeller system is provided with a multiple ring structure formed with a plurality of circular or non-circular, annular, narrow equivalent air foil rings which are held by rails in a predetermined relationship with the propeller blades. The upstream ring is located downstream from the tip vortex of the propeller within the axial span of the propeller. One or more additional downstream-located rings are used so as to provide at least one annular multiple ring-defined pump aperture through which peripheral vortices generated by the propeller blades or fan blades may enhance the mass flow. In one propeller system, a low-aspect-ratio propeller is employed with high blade angles of attack and non-stall capability to generate strong vortices which enhance the beneficial effect of the multiple ring structure. These vortices increase thrust because their induction action on the rings increase beneficial ring flow circulation.

Abstract: Disclosed herein is a lower unit for a marine propulsion device, such as an outboard motor or a stern drive unit, which lower unit comprising a gear case including a torpedo having a fore and aft axis and including a forward portion, a central portion extending rearwardly from the forward portion and having a generally cylindrical configuration concentric with the axis and defined by a radius, and an aft portion extending rearwardly from the central portion and including a circumferentially extending cylindrical sub-portion which is concentric with the axis, and which is defined by the radius, and a circumferentially extending conical sub-portion which is concentric with the axis, which extends for a circumferential length of not more than 180.degree., and which is defined by radii which are greater than the radius and which gradually increase in the direction toward the aft end.

Abstract: The invention discloses a pontoon boat adapted to be propelled by an outboard motor, the boat having a deck and pair of longitudinally extending parallel spaced apart pontoons depending from the deck and a means for mounting the outboard motor to the boat. The mounting means depends from the deck between the pontoons and comprises a pair of elongated substantially vertical spaced apart side walls having front and aft ends, the side walls becoming deeper and more spaced apart as they extend from their front ends to their aft ends, a substantially vertical and laterally extending transom positioned between the side walls at the aft ends thereof and a bottom portion, the bottom portion depending from the side walls and having a V-configuration in cross section and extending rearwardly of the side walls and the transom.

Abstract: A strut mounted, counter rotation marine propeller propulsion system of the single engine is provided including a depending propeller shaft strut from which aligned front and rear propeller shafts are supported including remote ends disposed exteriorly of the strut and having front and rear propellers, respectively, mounted thereon and adjacent ends drivingly interconnected through the utilization of bevel gearing within a journal hub carried by the lower end of the strut. The forward extremity of the front propeller shaft is removably coupled to the rear end of a rearwardly and downwardly inclined power shaft journaled through the bottom of the associated hull and the strut includes horizontally outwardly projecting and forwardly and upwardly inclined opposite side water deflector plates for smoothing out the water discharge, in conjunction with the strut itself, from the front propeller.

Abstract: A turbine type, jacketed propeller which has a venturi jacket formed around and with the propeller. The propeller blades are shaped in conjunction with the jacket so as to load the blades with more water and keep the water on the blades to help maintain pressure for propulsion.

Abstract: An asymmetric set of pre-swirl vanes (stators) and a specially matched propeller for use on an inclined shaft. The propeller is designed by considering the mutual interaction of the propeller on the vanes and the vanes on the propeller. The propulsor unit provides the following:1. increased propulsion efficiency due to the reduced rotational (swirl) and axial kinetic energy losses in the propulsor's slipstream;2. reduction or elimination of propeller cavitation;3. reduction or elimination of unsteady propulsor forces as well as propulsor-induced hull vibrations.A unique feature of the present invention is that a prior art flat faced commercially available propeller can be modified to match the vane flow field for optimum propulsor performance. The use of commercially available propellers reduces the installation or hardware cost significantly and allows the propeller to be repaired easily if damaged.

Abstract: A device, such as a boat hull and propulsion system, for effecting relative movement of a flowable substance, such as water. A channel having open upstream and downstream ends at least partially defines a flow path. The channel includes a fully laterally closed core section distal the upstream end with a fluid moving rotor rotatably mounted therein and a transition section extending forward from the upstream end of the core section. The channel configuration and rotor are adapted to permit a continual decrease in the transverse cross-sectional area of the flow path downstream along the transition section. If the device is a boat hull, the bow is configured to cause gas lubrication thereof by interaction with the water in motion. The transition sections of the channels may be open-bottomed, and ribs are provided to house drive shafts extending downwardly to the rotors.

Abstract: A watercraft performance type device for facilitating the on-plane operation of a watercraft comprising a plate-like member which is specifically designed to be removably attachable to the underside portion of the cavitation plate associated with the lower drive unit of a typical outboard motor or stern drive assembly, the plate-like member including an angularly related tab portion extending downwardly substantially across the rear end portion thereof, an opening strategically positioned for receiving the downwardly extending torque tab commonly associated with most cavitation plates, the torque tab opening being located and dimensioned so as to enable the torque tab to extend therethrough when the plate-like member is attached in operative position to the underside portion of the cavitation plate, and a cut-out arrangement associated with the front end portion of the plate-like member for positioning and locating the same in close abutting relationship with that portion of the lower drive unit located adjac

Abstract: The invention relates to a pair of five-sided hydrofoils for use in conjunction with the lower unit of a conventional outboard motor. The invention improves the stability of a boat and reduces the time required for a boat to achieve a planar configuration with respect to the surface of a body of water. The hydrofoils include leading edges having upturned angular portions and trailing edges having downturned angular portions. The leading and trailing edges are designed to simultaneously apply a lifting force to the stern and a downward force to the bow of a boat as the boat is propelled through the water. The invention improves the performance, safety, comfort, and useful life of a boat and a conventional outboard motor.

Abstract: The device induces cavitation in at least a propeller of an engine-driven watercraft with a planing or semiplaning keel. The device generates a depression area in the front part of the same propeller and connects the area with atmosphere by air ducts, thereby allowing planing speed to be attained more rapidly and better utilization of the engine power during the transient stages before attaining planing speed.

Abstract: A hull for a water vessel which includes an elongated displacement vessel having bow and stern extremities, a major longitudinal and normally horizontal axis, a vertical and normally perpendicular axis, a length of about L along the longitudinal axis, a propeller mechanism near the stern extremity and a guide vane which is located at a distance of between about 1/4 L and 1/2 L (preferably about 1/3 L) ahead of the propeller mechanism.

Abstract: A hydrofoil for mounting on the lower unit of a marine outboard engine/marine outdrive which improves the performance and stability of a boat driven by the lower unit. Each hydrofoil includes an upwardly angled wing segment and a wingtip fin at the outer end of the wing segment. The hydrofoils are preferably mounted in a pair on the lower unit and form a V-shaped assembly. Alternately, the hydrofoils may be formed as a single unit in which they are joined near their trailing edges. When mounted on the lower unit on a boat with a V-shaped hull bottom, the hydrofoil assembly generally matches the hull bottom shape to lower drag and water resistance during operation and to prevent interference with the forks of a fork lift truck when the boat is lifted.

Abstract: An asymmetrically arranged hydrofoil and propeller system is disclosed for improving the speed and lift of watercraft such as amphibious vehicles. When the vehicle is propelled through water by propellers, a downwash of water from the upper surface of the asymmetrically arranged hydrofoils is intercepted by upwardly moving propeller blades which improve the speed, lift and efficiency of the watercraft.

Abstract: A combination steering attachment and stand for electric trolling motors to permit the more efficient use of low thrust electric trolling motors for steering a boat and to also provide a stand to set the trolling motor on when it is removed from the boat. The attachment includes two flanking plates that extend parallel to and alongside the electric motor and the propeller and remain in a fixed parallel relationship to the axis of rotation of the propellor to continually direct all of the motor thrust along the axis extending through the propeller. The flanking propellor plates also protect the propellor from hitting obstructions in the water.

Abstract: Apparatus for reducing cavitation erosion is disclosed which includes ducts and openings (30, 32, 34, 40) for discharging a stream of gas positioned upstream of and adjacent to a propeller (11), in a direction perpendicular to the oncoming flow and at a lateral position relative to the propeller rotation axis.

Abstract: Method and arrangement for the reduction of the resistance to rotation of the propeller (3) of a ship (1) going in ice when the ice increases the resistance to rotation of the propeller to a level higher than when sailing in open water. When the resistance to rotation increases, gas is passed to the propeller (3), and the supply of gas is adjusted when the resistance to rotation is changed. The supply of gas may be continual, but as a rule it is used only for short periods in order to correct the speed of rotation of the propeller to the appropriate level.

Abstract: In a drive arrangement for a planing hull boat in which a drive shaft extends from a motor within the hull through the stern wall to a propeller arranged in a tunnel-shaped water flow guide structure extending backwardly from the bottom edge of the stern wall and upwardly in a curved fashion, the propeller is mounted so as to be rotatable about an axis which is essentially parallel to and in alignment with the hull bottom. The flow guide structure has a top end section hinged so as to be tiltable about a horizontal axis between the guide structure side walls and, at its front end adjacent the rear hull bottom edge, a scoop adapted to scoop up a stream of water which is directed over the flow guide structure to form a water seal preventing in leakage of air into the water flowing through the flow guide structure.

Abstract: The device induces cavitation in the propeller of engine-driven watercraft with planing or semiplaning keels, thereby allowing planing speed to be attained more rapidly and greater utilization of the engine power during the transient stages before attaining the planing speed.

Abstract: An outboard motor supporting arrangement of a boat includes a stern bracket fixed to a transom of the boat. The stern bracket is U-shaped, and has a flat bottom and left and right side walls extending upwardly from left and right ends of the bottom. Each side wall includes a slant section and a vertial section extending upwardly from an upper end of the slant section. In each side wall, there is further formed a projecting portion projecting outwardly, and extending longitudinally of the boat, for preventing water from be splashed on the outboard motor.

Abstract: Disclosed herein is a propeller guard device, including a laterally extending fin and a vertical extension, or sleeve. The fin and sleeve could be manufactured as a singular item. The vertical sleeve is attached to the midline area of the fin, with the leading edge of the sleeve being generally co-terminus with the leading edge of the fin. The fin is at least as wide as the rotational path of the propeller blades. The singular fin extends laterally on either side of the sleeve in a generally coplanar relationship. The leading edge of the fin is elevated from three to five degrees higher than the trailing edge of the fin. The trailing edge of the fin is located forwardly of the rotational path of the propeller blades, or is lengthened and extends towards the rear of the device to the extent of being even with the midline of the rotational path of the propeller blades.

Abstract: Each stabilizing fin is provided with a thickened trailing edge in order to act as a flap for inducing drag during start-up. The induced drag serves to minimize the time within which the fin moves into a planing position. The recess on the bottom surface of the fin enhances the lifting force on the fin during stabilization without imposing undue drag forces during high speed travel of a boat.

Abstract: A control surface design for submerged vehicles. The control surfaces are vably mounted or radially extending support members such that the wake created by the deflection of the control surfaces will not be transmitted to the propeller. The support members have a cross section that minimizes flow disturbances in the region of the propeller.

Abstract: Method and arrangement for the reduction of the resistance to rotation of the propeller (3) of a ship (1) going in ice when the ice increases the resistance to rotation of the propeller to a level higher than when sailing in open water. When the resistance to rotation increases, gas is passed to the propeller (3), and the supply of gas is adjusted when the resistance to rotation is changed. The supply of gas may be continual, but as a rule it is used only for short periods in order to correct the speed of rotation of the propeller to the appropriate level.

Abstract: The present invention provides a stabilizer attached to the cavitation plate on the leg of a motor boat motor. Two elongated tubular members are attached by mounting brackets to the motor's cavitation plate. The tubular members are attached at a downward angle away from the boat so that an upward force is created by the hydrodynamic jet action of water flowing through the tubular members at the rear of the boat when the boat moves in a forward direction. The upward jet created force at the rear of the boat keeps the boat horizontal and stable at increasing speeds and at high speeds.

Abstract: A hull for a water vessel which includes an elongated displacement vessel having bow and stern extremities, a major longitudinal and normally horizontal axis, a transverse and normally perpendicular axis, a length of about L along the longitudinal axis, a propeller mechanism near the stern extremity and a guide vane which is located at a distance of between about 1/4 L and 1/2 L (preferably about 1/3 L) ahead of the propeller mechanism.

Abstract: Flow guiding faces (1,2) adapted to be arranged at the rear end (4) of a ship with at least one propeller (5). Each flow guiding face is located in front of a propeller (5). The center of the area enclosed by each flow guiding face (1,2) and the hull lies above the centerline of the propeller (5). The spatial angle between the centerline of the flow guiding faces (1,2) and the longitudinal axis of the ship is adjustable.

Abstract: A boat or ship's propeller system utilizes a rotary propeller comprised of a plurality of short blade elements arranged annularly and supported from a central propeller shaft by spokes, there being an annular "funnel" with the large end forward which scoops water and delivers it under some pressure to the rotating annular ring of blade elements.

Abstract: An asymmetric set of pre-swirl vanes (stators) and a specially matched propeller for use on an inclined shaft. The propulsor is designed by considering the mutual interaction of the propeller on the vanes and the vanes on the propeller. The propulsor unit provides the following:1. increased propulsive efficiency due to the reduced rotational (swirl) and axial kinetic energy losses in the propulsor's slipstream;2. reduction or elimination of propeller cavitation;3. reduction or elimination of unsteady propulsor forces as well as propulsor-induced hull vibrations.A unique feature of the present invention is that a prior art flat faced commercially available propeller can be modified to match the vane flow field for optimum propulsor performance. The use of commercially available propellers reduces the installation or hardware cost significantly and allows the propeller to be repaired easily if damaged.

Abstract: The invention is a manoeuvring device for boats, comprised of a pair of pivotal tube plates (17, 18) mounted outside a propeller 14 and, under normal operation, forming a tube (19) around the propeller. These plates can be swung to one side relative to a medial position to enable sideways steering of the vessel, and be brought together astern of the propeller to form a blade when reversing. The tube plates (17, 18) extend down beneath the propeller (beside 19B). A tube wing (20), extending in a longitudinal direction, is mounted immediately beneath the propeller (14) and is arched upwards towards the propeller wings. Under normal operation, a tube that is sickle-shaped in cross section is delimited between the tube wing and the lower portion of the tube plates. The pivot axis of the tube plates (17, 18) is preferably located close to the propeller wing plane.