Abstract: In accordance with one embodiment of the present invention a surface ship having at least one tractor podded propulsor is provided. The vessel having a tractor podded propulsor system comprises a hull means and at least one tractor podded propulsor unit attached to the aft section of the hull means. The at least one tractor podded propulsor unit comprises an axisymmetric pod having a longitudinal centerline associated therewith, at least one propeller mounted for rotation to a forward end of the pod, and a substantially vertically aligned streamlined strut connected at a top end to the aft section of the hull means and connected at a bottom end to the pod. The pod has a forward end and a tapered aft end. Mounted within the pod is at least one rotatably mounted propeller shaft that extends forward of the pod forward end, shaft seals, thrust bearings, and power means functioning to rotate the at least one propeller shaft.

Abstract: A powered swimming aid comprising a stabilizing member attached to the users back, and buoyancy device rigidly attached to the stabilizing member, the buoyancy device being located below the user's hips so as to cause the body to rotate to a good swimming position. The rigid structure also has mounted on it a drive mechanism terminating in a propeller located below the user's hips so as to cause the body to rotate to a good swimming position. The rigid structure also has mounted on it a drive mechanism terminating in a propeller located below the user's knees to provide powered motion in the motor. A buoyant board has side handles and a control for controlling the drive mechanism. A buoyant vest is worn on the user's chest.

Abstract: An auxiliary propelling structure can be attached to an existing propeller system including a propeller having a boss, a propeller shaft and a tightening nut screwed onto the end of the shaft. The auxiliary propelling structure includes an auxiliary boss that is approximately cylindrical to enclose closely the tightening nut of the existing propeller system and having an internal partition with a central through-hole. The partition is pressed against the tightening nut.

Abstract: This invention relates to a device for use with a ducted propeller system r suppressing gap cavitation between a moving rotor tip and duct wall and more particularly to means for supplying fluid to a ducted propeller whereby cavitation or the noise resulting therefrom may be eliminated.

Abstract: Disclosed herein is marine apparatus comprising a boat including a hull, an outboard motor including a propulsion unit having a rear side and mounted on the hull for pivotal movement relative thereto between a trimmed-in position, a tilted-up position, and a trimmed-out position between the trimmed-in position and the tilted-up position, a cover which extends above the propulsion unit and which is mounted on the hull for movement relative thereto about an axis located forwardly of the rear side of the propulsion unit and between a lower position wherein the cover affords movement of the propulsion unit between the trimmed-in position and the trimmed-out position, and an upper position wherein the cover affords movement of the propulsion unit to the tilted-up position, and engaging surfaces on the motor and on the cover for moving the cover from the lower position to the upper position in response to movement of the propulsion unit from the trimmed-out position to the tilted-up position.

Abstract: The invention relates to hand-insertable, rigid plastic cover for use with an individual boat blade of a propeller of an in-board or outboard boat motor wherein each cover of the invention is integrally formed as a single unit using of a conventional plastic material such as polyethylene. Briefly, the plastic cover of the invention comprises a pair of broad side walls of a tear-dropped or elliptically shape placed in a side-by-side relationship and terminating at a U-shaped closed edge or end wall but being open at a concavely formed, transverse open top to permit easily insertion over the leading and trailing edges of each blade.

Abstract: A propeller has a hub affixed to a propeller shaft so as to rotate therewith. The hub is axially locked by a locking arrangement consisting of a lock nut screwed on to the shaft and a lock screw screwed into the end of the shaft to lock the nut. The screw is tightened more than the nut in order to cause the thread on the nut to load the opposite thread flank on the shaft. A portion of the nut which is deformed during tightening of the screw holds the nut and screw together during subsequent removal of the propeller.

Abstract: A sleeve 18 spline-fitted in an outer periphery of a propeller shaft 4 is connected to a propeller boss 12 for surrounding the outer periphery of the sleeve by a damper rubber 20 interposed in superposed relation therebetween, and in a recess formed in the outer periphery of the propeller boss 12 so that a bottom surface thereof comes near the outer periphery of the damper rubber 20, propeller blades are rotatably supported on a blade shaft 33 parallel to the propeller shaft 4. With this arrangement, it is possible to provide a compact variable propeller for a boat which can be mounted on a relatively short propeller shaft and which is provided with a torque limiting device.

Abstract: A plastic propeller for marine electric trolling motors modified to prevent the entanglement and build-up of weeds by the application to its surface of a thin sheet of metal formed in the shape and size of the blade and extending beyond the blade's leading edge.

Abstract: An outboard motor adaptor (10) comprises an upper housing (12) provided with a connection bar (24) having formations (28, 30) thereon for engaging with bar studs (44) on a chainsaw housing (42). A stem (14) extends from the upper housing (12) and a lower skeg and propeller portion (16) is provided on the opposite end of the stem (14). The skeg and propeller portion (16) is provided with a propeller (32) thereon. A drive sprocket (22) is provided on the upper housing (12) adjacent the bar (24). The drive sprocket (22) is operatively connected to the propeller (32) for driving the propeller (32). A drive chain (26) extends around the drive sprocket (22) and the connection bar (24). A space (48) is provided between the bar (24) and the drive chain (26) at the location opposite the drive sprocket (22) for receiving a chainsaw sprocket (46) of a chainsaw motor in the space (48) to engage with the drive chain (26), thereby to drive the drive sprocket (22) and the propeller (32) through the drive chain (26).

Abstract: A boat motor conversion apparatus for converting a line trimmer into a boat motor comprising a tube having an upper end and a lower end, the upper end adapted to be coupled to a line trimmer's motor housing; an elongated drive shaft disposed within the tube, the drive shaft having a tip end extending from the upper end of the tube and a base end extending from the lower end of the tube, the tip end adapted to be coupled to a line trimmer's drive motor, whereby the drive motor rotates the drive shaft within the tube when activated; a boat motor having a plurality of gears coupled to the base end of the drive shaft for redirecting rotational movement therefrom and a propeller coupled to the gears; and a securement mechanism coupled to the tube and adapted for securing the tube to the stern of a boat.

Abstract: A folding blade propeller for a power vessel wherein the blades are synchronized in their pivotal movement as they pivot from one position to the other by flexible links. The flexible links are connected at one end thereof to the base of one propeller blade and at the opposite to the base of another and act as pulling members. When one blade pivots the flexible link pulls on the base of the other blade to which it is attached to simultaneously pivot that blade. Slack in the links is minimized by having each link in rolling contact with rounded surfaces on the base of the respective propeller blades that are interconnected by that link.

Abstract: A marine propeller which includes arcuate ribs extending from each blade surface. Each rib is widely spaced at the blade's leading edge and curves inwardly towards the propeller hub to substantially converge at the blade's trailing edge. Each rib is further configured so as its height above the blade surface is highest at the blade's trailing edge and is tapered to a lower height at the leading edge. This rib configuration provides a greater blade surface area to produce greater thrust and overall higher propeller efficiency.

Abstract: A cover for a propeller is disclosed which is intended to be used while a boat on which the propeller is mounted is being transported on a trailer. The cover is either made of a reflective material or is covered with a reflective material and is intended to reflect light from headlights of vehicles following the trailer to provide an added safety factor when a boat is being towed by a vehicle.

Abstract: A drive for a boat has a propeller hub rotatable about a main axis extending in a normal travel direction, a plurality of blades projecting generally radially of the main axis from the hub and each pivotal so as to be of variable pitch, and respective blade rods extending axially and displaceable axially relative to the hub to vary the pitch of the blades. A stator carried on the boat downstream in the direction from the hub and nonrotatable about the axis rotatably supports a cylinder housing that is releasably connected to the rods for joint axial movement therewith. A piston displaceable along the axis in the cylinder is releasably connected to the hub for joint axial movement therewith. Pressurizable lines extending through the stator are connected to the cylinder for alternately pressurizing the piston and thereby relatively axially shifting the rods and hub.

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: A marine propulsion device including a lower unit, a propeller shaft rotatably supported by the lower unit and to support a propeller, the shaft including a longitudinal axis and a surface defining a plane which is substantially normal to the axis, and a thrust washer for transmitting thrusting force from the propeller to the surface.

Abstract: A marine propeller with break away hub has an insert cavity with pentagonal cross section extending coaxially with the axis of rotation of the propeller, along at least a portion of the length of the propeller. A resilient insert corresponding to the insert cavity is positioned in the insert cavity. The insert is sized for slip fit with the cavity and is adapted for connection with a propeller drive shaft. Preferably, the insert has a cylindrical aperture with a series of grooves disposed circumferentially thereabout extending coaxially through the insert and the insert is connected with the propeller shaft through a shaft sleeve. The shaft sleeve corresponds to the aperture in the insert, has a cylindrical outer surface with a series of teeth disposed circumferentially thereabout, and has a mounting aperture extending coaxially through the shaft sleeve. The shaft sleeve is sized for hand force slip fit engagement with the insert.

Abstract: Hydraulic air compressor and fuel fired turbine apparatus disposed in a vessel or ship includes a hydraulic compressor having an air intake disposed above the water intake for entraining air in falling water, and the output of the hydraulic compressor is used as a compressed air source for turbine apparatus. The turbine apparatus includes a regenerator for heating the incoming compressed air output from the hydraulic air compressor. The hydraulic air compressor includes, in one embodiment, pump elements for providing a flow of water for when the ship or vessel is not moving and a flow of air to be entrained and compressed.

Abstract: The propulsor comprises a main engine, a fixed tubular part, a main transmission which ends with a substantially vertical shaft which operates a bevel gear on the substantially vertical shaft which operates a bevel gear pair on the substantially horizontal outlet of which a propeller is placed, an auxiliary transmission which carries out the rotation around a vertical axis of the bottom end of the propeller, a moveable assembly which moves vertically with respect to the fixed structure of the boat and is integral in this direction with the bevel gear pair and with the propeller. It is characterized by the fact that said moveable group is made of an inner part which can rotate with respect to a vertical axis which rests vertically, on a moveable carriage, the lower end of which extends downwards at least to the level of a fixed support integral with the structure of the boat.

Abstract: A relatively small and light weight personal watercraft includes a driveshaft tunnel which permits the driveshaft housing of a string trimmer apparatus to be installed therein. The string trimmer apparatus is modified by removing the string trimmer or other head which may be attached, installing a propeller(s) or impeller(s), removing any handles from the string trimmer, temporarily removing the power head so that driveshaft housing may be installed within the driveshaft tunnel of the watercraft, installing a fairing (if desired) and/or handlebars, and reattaching the throttle control to the handlebars. The modified string timmer may be used as both a power system for the watercraft and also provides directional control by turning the attached handlebars or fairing in order to rotate the power system about an axis concentric with the driveshaft and thereby change the direction of the thrust line of the propeller(s) or impeller(s).

Abstract: Apparatus for emergency enablement of a boat propeller. The apparatus comprises a central mounting plate having an aperture for engagement with one end of the propeller shaft to which the propeller is attached. A plurality of cantilevered members, the proximal ends of which are fixed at spaced intervals around the periphery of the central mounting plate, extend perpendicular to the mounting plate for disposal within longitudinal spaces of the boat propeller.

Abstract: A marine drive (10) has a propeller (12) with a hub (14) mounted on a propeller shaft (22). A rear thrust hub (30) has one or more slots (40) spaced circumferentially around the propeller shaft. A nut (42) is threaded onto the propeller shaft to mount the propeller. A locking tab washer (60) around the propeller shaft between the nut and the propeller hub has one or more circumferentially spaced tabs (66) bendable forwardly into slots (40) of the rear thrust hub (30) and has ears (68) extending perpendicularly rearwardly from outer tips of the tabs externally of the slots. The ears may be gripped and pulled to bend the tabs rearwardly out of the slots, to enable removal of the nut, and hence removal of the propeller.

Abstract: Apparatus shears foreign matter such as lines, wires, nets and weeds that can entangle and befoul propellers, propeller shafts, bearings and related structure of propeller-driven, water born vessels. The apparatus shears by cooperative action of a rotating blade that rotates in conjunction with the propeller and a non-rotating blade supported on a non-rotating portion of the vessel. The non-rotating blade moves axially within its support. With each revolution, a slot follower connected to the non-rotating blade engages a slot carried by the rotating blade to adjust the axial position of the non-rotating blade to compensate for axial movement of the rotating blade. A wedge and valley mechanism prevents the two blades being forced apart during shearing action.

Abstract: An outboard trolling motor mount for use in mounting an outboard trolling motor on the outboard drive unit of a boat equipped with an inboard/outboard type power unit is disclosed. The motor mount includes a mounting block for supporting an outboard trolling motor and a support structure attachable to the outboard drive unit through the drive unit's top cover for supporting the mounting block to one side of the drive unit at a location behind the boat's transom.

Abstract: A kit for converting a Weedwacker into an outboard engine and a method of using the kit includes the steps of rotating the tubular housing of the Weedwacker through one hundred eighty degrees, replacing the grass cutting device with a propeller, replacing the muffler of the Weedwacker with an elongate exhaust tube, clamping the exhaust tube to the tubular housing, and mounting a swivel support bracket to the tubular housing.

Abstract: Disclosed herein is a marine propulsion device comprising a lower unit including a gear case, a propeller shaft extending in the gear case, an annulus of greater dimension than the propeller shaft and of material weight, and a ring of elastomeric material resiliently connecting the annulus to the propeller shaft is co-axial relation thereto so as to provide for rotation of the annulus in common with rotation of the propeller shaft.

Abstract: A jet propulsion engine submergible in water for driving a water craft wherein a drive shaft is connected to an internal combustion engine for rotation thereof. A first turbine is mounted on the drive shaft for rotation therewith for providing a first high velocity stream of water axially through the propulsion engine. A propeller is journalled on the drive shaft adjacent to and downstream of the first turbine for rotation independently of the drive shaft. A second turbine is mounted on the drive shaft adjacent to and downstream of the propeller for rotation therewith for generating a second high velocity stream of water axially through the propulsion engine. The speed of the propulsion engine increases through the effects of the first and second high velocity streams of water for driving the water craft while the propeller becomes less effective until it is rendered free wheeling at cruising speeds of the water craft.

Abstract: The invention relates to a profiled device configured as a slotted blade head to improve the efficiency in blade-like structural elements that have a gas or a fluid flowing around them such as foils, vanes of jet engines, propellers, keels of ships or the like. The blade head is formed of a group of profiled blade elements (3) having a laminar profile with radially running slots formed between the blade elements at a distance from the base of the blade head. End edges (4) of the blade elements (3) that are consecutive in an initial flow direction (X) are offset relative to each other each in the direction of a pressure zone (6). Slots (2) between the blade edges (4) are of a nozzle-shaped configuration with a flow direction extending from the pressure zone (6) to the underpressure zone (5). The blade elements (3) are located within a profile envelope (73) set by the blade base of the group of blade elements.

Abstract: Discussed herein is an arrangement for reducing migration of weeds into an area between the gearcase and the propeller hub of a marine propulsion device. The arrangement is intended to reduce the problem of weed migration when a small hub propeller is used.

Abstract: A marine drive for a boat (3) includes a longitudianlly extending propeller shaft (17, 37, 38) which effectively carries the propeller hub (18, 41, 42) between a pair of fore and aft conical surfaces (26-29; 44-47; 51-54) which mate with similar conical surfaces associated with the hub. These mating surfaces prevent orbiting movement of the propeller. The mating surfaces also center the hub on its axis and provide for high torque retention. The construction is such that water is kept out of the joint between the hub and propeller shaft, with pre-applied lubricant being retained therein. The inventive concepts may be utilized with a single propeller system (FIG. 2), or dual propeller installation (FIG. 4).

Abstract: A device for increasing the efficiency of operation of an internal combustion engine used in outboard and inboard/outboard motors comprised of a generally cylindrical member having inner and outer peripheral shell members defining a cylindrical annular space therebetween, wherein are located a plurality of turbine vanes spanning the annular volume between said inner and outer shell members. Said inner and outer shell members and said plurality of vanes are drivingly connected to the propeller shaft of an outboard motor and are mounted coaxially with said propeller shaft. The device is located in the forward end of the inner propeller hub and rotatably mounted in association with the lower unit of said outboard or inboard/outboard motor so that exhaust gases flowing through said lower unit pass through said annular volume. Upon rotation of said propeller shaft, said plurality of vanes are caused to rotate at the same angular velocity thereof.

Abstract: An improved lubricating system for the internal combustion engine of an outboard motor. A lubricant sump is positioned beneath the engine and oil is returned to the sump through a drain opening in a spacer plate that separates the engine from the drive shaft housing. The oil sump and drain opening are configured so that oil will not return from the sump through the drain opening to the engine when the outboard motor is laid on its side edge.

Abstract: A device mounted in encircling relation to a propeller shaft. The device cuts lines, nets and weeds, thus preventing entanglement of the propeller and preventing entanglement damage which may result to the parts of the driven assembly of the outboard, inboard/outboard or trolling motor used to propel vessels through the water. The device includes a non-rotatable, annular cutting ring member having one or more double-edged cutting blades, that is disposed in sandwiched relation to two rotatable annular members. One of the rotatable members carries no cutting blades, and the second rotatable member carries a plurality of double-edged, circumferentially spaced blades that individually cooperate with the non-rotatable blade in a shearing action. The non-rotatable member includes a protruding, forwardly expanding, wedge member, the wedge member being configured to define a forwardly opening wedge-shaped cavity.

Abstract: A marine propulsion device including a propeller shaft, a lower unit rotatably supporting the propeller shaft and including a lower unit exhaust passageway, and a propeller adapted to be submerged in water and including an inner hub connected to the propeller shaft. The propeller also includes an outer hub connected to and spaced from the inner hub and defining a propeller exhaust passageway having an inlet in communication with the lower unit exhaust passageway, a plurality of blades extending from the outer hub rearwardly of the inlet, an opening for communicating the lower unit exhaust passageway with water outside of the outer hub, and a member located adjacent and rearward of the opening, and extending forwardly and radially outwardly with respect to the propeller shaft.

Abstract: The present invention relates to an adapter for converting a conventional apparatus used for cutting and trimming vegetation into a device for propelling a boat. The adapter includes a screw propeller mounted to a centrifugal clutch which is driven by the motor of the apparatus for cutting and trimming vegetation.

Abstract: A shell made up of opposed halves is fitted over the propeller screw of the motor on the boat. This shell then becomes an enclosure with inlet and outlet openings at the ends. This shell with the propeller screw forms a pump with the propeller screw pumping water through the shell and through an outlet hose which is extended to the shore. One form has the inlet and outlet openings on the axis of the propeller screw and other forms include the outlet arranged tangentially or angularly. A hose can be connected to the inlet opening for bailing a boat.

Abstract: A propeller assembly (2), a so-called thruster, intended to be fitted to an opening (7) in a bottom part (1) of the shell structure of a watercraft, for example an offshore-platform, is provided with a mounting flange (9) which can be connected in a pressure tight fashion to the shell structure around the opening (7). To enable the assembly to be fitted and dismantled from outside the shell structure and beneath the surface of the water on which the craft floats without requiring the assistance of a diver there are used a plurality of lines (12) which can be connected to lifting devices in the watercraft and passed out through a corresponding number of line openings (13) located in the shell structure on one side of the assembly mounting opening (7), so that the ends of the lines can be connected to the line attachments (16; 37) on the assembly (2).

Abstract: A stop device for application to an outboard marine engine to retain the propeller against rotation while the prop nut is being tightened or loosened. The device is T-shaped and includes side wings and a vertical leg. The wings have slots which permit the device to be slipped onto a tail plate located above the propeller. The leg extends downwardly between the blades of the propeller and engages the blades to prevent propeller rotation.

Abstract: A method and apparatus is provided for converting a gasoline motor powered line trimmer into an outboard trolling motor. The method includes the removal of the trimmer line spool head from the lower end of the trimmer and the replacement of the head with a marine propeller, the removal of the usual handle from the upper end portion of the housing of the trimmer and the replacement of that handle with a conventional trolling motor transom mount and the addition of a clamp mounting steering arm to the upper end portion of the housing of the trimmer and the relocation of the throttle control assembly of the trimmer from the upper end portion of the trimmer housing to the free end of the steering arm.

Abstract: The mounting of a thruster propeller unit in the bottom plating of a vessel is facilitated by the use of lifting lines, operable from within the vessel. Each line is made to pass a lock chamber adjacent to an opening in the bottom plating, outside the opening where the thruster propeller is to be fitted. The lock chamber includes a first, rigid tubular member, which is formed as the housing for a slide valve, as well as a second tubular member, which is resilient at least in the transverse direction. The two tubular members define a passage being substantially wider than the diameter of the lifting line. The second tubular member is at its top provided with a sealing sleeve which fits around the line. The locking chamber is connected to a source of compressed air, which makes it possible to maintain a pressure within the chamber balancing the pressure of the surrounding water.

Abstract: An improved efficiency propulsion system and method of improving the efficiency of a vessel operated in deep and shallow water depths and at constant or variable loaded and ballast waterlines contemplates the use of a variable diameter propeller means capable of varying between a maximum extended diameter D and a minimum effective diameter D mounted on a propeller shaft having an axis of rotation displaced from the bottom keel of the ship a distance less than one-half the maximum diameter D of the propeller means. In this way, because of the use of the variable diameter ship propeller, the propulsion shaft may be located closer than otherwise permissible to the bottom keel of the ship which has the result of lowering the top blade tip trajectory relative to any particular chosen waterline and also providing space for a generally larger diameter more efficient propeller installation.

Abstract: A method is provided for the fabrication of a steel propeller which is designed to have a final shape and size consistent with a conventional propeller design. The resultant formed propeller includes n individual blades, each having boss segments. When the boss segments of the individual blades are joined together they form a propeller having a center boss portion. A center aperture may thereupon be drilled or bored in the boss for mounting the propeller on the shaft of a marine engine. The propeller is formed, in accordance with the method of the present invention, by individually press-forging n steel blanks into individual blade portions which include boss segments. The press-forged blades are then ground with their lateral surfaces beveled to permit them to be welded together into a whole propeller. The center aperture is then formed and the propeller finally heat treated and finally ground.

Abstract: The marine propulsion device lower unit includes a housing having a lower portion submerged in water and defining an internal passage communicating with the water. Corrosion protection for both internal and external parts of the lower unit is provided by a sacrificial, galvanic-type anode mounted on the submerged portion of the housing and including a first or outer portion having a surface exposed to water exterior to the lower unit and a second or inner portion having a surface exposed to water present in the passageway.

Abstract: A propulsion unit for a water-borne vessel has a drive transmission assembly comprising a drive shaft and a steering shaft which can be concentric with the drive shaft, a leg depending from the drive transmission assembly, for instance by way of a horizontal axis pivot connection so that the leg can be swung up, and a propeller housing supported on the lower end of the leg for rotary movement about the axis of the leg, for steering the vessel.

Abstract: A marine propulsion device is provided including a lower unit having a gearcase and a propeller shaft housing located in the gearcase and supporting a propeller shaft for rotation. A propeller is mounted on the propeller shaft rearward portion for common rotation with the propeller shaft. A thrust bushing is carried by the propeller shaft and for transmitting forward thrust from the propeller to the propeller shaft. An annular sacrificial anode surrounds the propeller shaft and is positioned between the thrust bushing and the propeller shaft bearing housing for providing cathodic protection for the rearward end of the gearcase and the propeller shaft bearing housing.

Abstract: A method of manufacturing boat parts submerged when in use comprises producing a metallic skeleton structure shaped for easiest production by conventional metal-forming methods, and covering this structure in a mold with an adhering layer or coating of a thermoplastic resin or a rubber-based vulcanizable substance. The inner walls of the mold have high finish and the desired streamlined outer shape of the finished product, such as a lower unit of a propulsion system, or a propeller and the like. The coating functionally neutralizes the technologically conditioned and generally not streamlined shapes of the skeleton structure and provides a protection of the skeleton structure against electroerosive corrosion.

Abstract: A propulsion device comprises a water intake and a conduit for conveying water from the intake to an aperture. Apparatus is provided for forcing the water through the aperture in the form of a water jet as well as for subdividing the water into segments and accelerating each of the segments into the air. The method for propelling the nautical vessel comprises flowing water through a water intake in the vessel and conveying the water through a conduit from the intake to an aperture. The water is forced through the aperture in the form of a water jet and subdivided into segments which are accelerated into the air so as to provide a reaction force for propelling the nautical vessel.

Abstract: A universal steering and propulsion unit for marine craft utilizes a power train which includes a differential gearing unit with control of the power delivered being accomplished through selective braking of one side of the differential. Steering may be accomplished by a 360.degree. rotating ability of the propeller without interruption of the power delivered to the propulsion unit. The power train also provides a special gearing arrangement whereby the propeller drive shaft may be driven so as to provide forward thrust regardless of the direction of rotation of the output drive shaft of the power unit, thus obviating the necessity for oppositely rotating output shafts when dual drive units are required. The oil pressure about the propeller shaft and gear transfer housing is used for feathering the propeller blades.

Abstract: A propeller (18) having an exhaust discharge passage (22) through the propeller hub has blades (24) symmetrical in thickness about the nose-tail pitch line and symmetrical in plan form about a rake line (26). The propeller (18) is particularly effective to increase reverse thrust when used with an outboard drive unit (10) having exhaust gas relief passages (27).