Abstract: Dual propeller assemblies for driving engagement by a propeller drive shaft may include at least two propellers having a forward propeller and a rear propeller rearwardly of the forward propeller. The forward propeller may include a forward propeller hub with a forward propeller hub wall having a forward propeller hub outer diameter. A forward propeller hub bore may be formed by the forward propeller hub wall and configured to receive the propeller drive shaft for driving engagement of the forward propeller hub thereby. The forward propeller hub bore may form a passageway for flow of exhaust gas configured to traverse the forward propeller between the propeller drive shaft and the forward propeller hub wall. The rear propeller may include a rear propeller hub with a rear propeller hub wall having a rear propeller hub outer diameter less than the forward propeller hub outer diameter of the forward propeller hub wall of the forward propeller hub.

Abstract: A system for propelling a paddleboard or surfboard along the surface of a body of water, comprising a controller motor coupled to a propeller, a rechargeable battery, a controller which may be wearable on the wrist of a user, and a housing structure that is adapted to be attached to the fin box of a paddleboard without the need to remove the fin. The apparatus presents a low-drag profile, has a long battery life for extended range, and is able to be controlled so that user may operate the paddleboard at any desired speed, and in a forward or rearward direction, or in a controllable direction of thrust. The housing structure is adaptable to various fin box T-bolt separation distances.

Abstract: Embodiments of the present invention are directed to devices adapted to enhance propulsion (i.e., propulsion enhancing devices) of watercraft such as, for example, personal watercraft and the like. To this end, a propulsion enhancing device in accordance with the disclosures made herein may be attached to or integral with (e.g., formed unitarily with a housing thereof) a propulsion unit of a watercraft. The propulsion unit generates a stream of water that provides for propulsion of the watercraft. A propulsion enhancing device in accordance with the disclosures made herein includes internal structures that enhance velocity and/or volumetric attributes of a stream of water generated by the propulsion unit by transforming non rotational flow at the inlet of the propulsion enhancing device to rotational flow at the outlet of the propulsion enhancing device.

Abstract: The trolling motor for an overboard person comprises a trolling motor and a wrist worn device. The trolling motor may be a battery-operated propulsion device that is operable to propel and steer a water craft. The wrist worn device may be worn by a person on the water craft. A control unit within the trolling motor may communicate wirelessly with the wrist worn device and may be cognizant of a relative position of the wrist worn device with respect to the water craft. If the person falls overboard, a separation distance between the wrist worn device and the control unit may increase. Upon a determination that the separation distance has exceeded a predetermined distance threshold, the control unit may direct the trolling motor to energize, deenergize, or reverse direction such that the trolling motor may move the water craft closer to the person.

Abstract: Embodiments of the present invention are directed to devices adapted to enhance propulsion (i.e., propulsion enhancing devices) of watercraft such as, for example, personal watercraft and the like. To this end, a propulsion enhancing device in accordance with the disclosures made herein may be attached to or integral with (e.g., formed unitarily with a housing thereof) a propulsion unit of a watercraft. The propulsion unit generates a stream of water that provides for propulsion of the watercraft. A propulsion enhancing device in accordance with the disclosures made herein includes internal structures that enhance velocity and/or volumetric attributes of a stream of water generated by the propulsion unit by transforming non rotational flow at the inlet of the propulsion enhancing device to rotational flow at the outlet of the propulsion enhancing device.

Abstract: Methods, systems, and apparatus for drone collision avoidance and acoustic sensing are disclosed. An example apparatus to detect acoustic data from a drone includes a controller to set a target revolutions per minute (RPM) for a motor of the drone. The controller is to modify the target RPM based on a modulation pattern to cause the motor to rotate a propeller of the drone at a modulated RPM. The modulated RPM creates self-generated noise. The example apparatus also includes a sensor to gather acoustic data and an analyzer to remove the self-generated noise from the acoustic data to create external acoustic data for processing.

Abstract: A marine propulsion system for shallow waters, swamps, savannahs and the like includes a rotating propeller shaft supporting a propeller. An anti-cavitation body defines a partial cylinder having a longitudinal axis adjacent to the propeller. The propeller generates a vacuum between the anti-cavitation body and a surface of a water body. First and second wings adjacent to edges of the anti-cavitation body are generally planar and operatively angled towards the bottom of a water body. The first and second wings are adjusted to run below the water body surface and seal the anti-cavitation body to maintain generated vacuum. A first thread is cut in a first helical direction at an end of the rotating propeller shaft adjacent the propeller, and slightly more distal therefrom a second thread is cut in a second helical direction opposed to the first thread helical direction. The second thread drives matter away from the bearing.

Abstract: A water diverter for outboard marine motors is presented. In one embodiment, the water diverter is adapted to be secured to a transom bracket which includes a portion adapted to be mounted on a boat transom. The water diverter includes a body and a bracket. The body has a horizontal deflection plate with a triangular shape. Two vertical deflection plates extend upward along the edges of the horizontal deflection plate. The bracket includes a horizontal mounting surface having a triangular shape. Two vertical attachment walls extend downward along the sides of the horizontal mounting surface. The bracket is sized to fit within the body with alignment of attachment openings of the vertical deflection plates and attachment holes of the vertical attachment walls determining a fastener-based selectively adjustable vertical displacement between the horizontal deflection plate and the horizontal mounting surface.

Abstract: Disclosed are a method and a virtual sensor system for determining the speed through water of a marine vessel. The method includes obtaining propeller revolutions per minute and at least one of torque at propeller, propulsion power, thrust and engine fuel flow, obtaining speed over ground of the vessel and using the obtained data and hydrodynamic modelling to determine the speed through water of the vessel.

Abstract: A marine propulsor comprises: a stationary part and a movable part which is movable relative to the stationary part; and a wireless communication system, comprising at least one transmitter which is disposed in the movable part and is configured to transmit an electromagnetic data signal and at least one receiver which is disposed in the stationary part and is configured to receive the electromagnetic data signal. The wireless communication system includes a diversity scheme for mitigating multipath distortion of the electromagnetic data signal between the at least one transmitter and the at least one receiver.

Abstract: An electrolytic protection system for stern drive marine motors having a cavitation plae, said system comprising an adaptors fixedly secured to said cavitation plate, and an anode mateable with said adopter.

Abstract: A propeller device for a marine vehicle with a main shaft; a front propeller is provided on the main shaft, the front propeller having a hub and a plurality of blades extending radially outwardly from the hub; a rear propeller being co-axially to and spaced from the front propeller, the rear propeller having a hub and a plurality of blades extending radially outwardly from the hub. A second shaft being communicated with the hub of the front propeller; and at least one support for supporting the rear propeller on the second shaft, the support prevents the second shaft to rotate in the direction of rotation of the main shaft, and being free to rotate thereof in the counter direction of rotation of the main shaft.

Abstract: A wake adjustment system for a boat may include a pair of wake adjustment devices mountable at the stern of the boat to deflect water moving past a stern trailing edge of the boat's running surface. A wake adjustment device includes a water deflector that is rotatable about a first pivot axis for varying a degree of wake adjustment. The pivot axis is non-parallel to the boat's stern trailing edge.

Abstract: A water jacketed exhaust component includes an exhaust pipe having a radially inwardly tapered tail end, a water jacket disposed in surrounding relation with the exhaust pipe, and a generally V-shaped spray ring. The spray ring includes a first and second set of apertures that create diverging streams of cooling water. A first set of apertures creates an annularly disposed series of streams that are directed downstream and radially inward. These streams are generally directed toward the outer surface of the exhaust pipe structure which extends downstream of the spray ring. A second set of apertures creates an annularly disposed series of streams that are directed downstream and radially outward. These streams are generally directed toward the inner surface of the water jacket structure extending downstream of the spray ring.

Abstract: A wake adjustment system for a boat may include a pair of wake adjustment devices mountable at the stern of the boat to deflect water moving past a stern trailing edge of the boat's running surface. A wake adjustment device includes a water deflector that is rotatable about a first pivot axis for varying a degree of wake adjustment. The pivot axis is non-parallel to the boat's stern trailing edge.

Abstract: Systems and methods for watercraft and marine propulsions systems having marine environment enhancement capabilities are disclosed.

Abstract: Exhaust gas from an engine passes through a lower unit, and passes through a propeller boss coupled to a propeller shaft to be discharged into water. An outside diameter of a front end portion of the propeller boss is set to be equal to or larger than an outside diameter of a rear end portion of a gear case in the lower unit.

Abstract: A prop shaft holder for an outboard motor includes a forward end for engaging a gear casing of the outboard motor and a rearward end axially spaced apart from the forward end. The rearward end includes an inner radial surface for engaging an outer radial surface of a propeller. The prop shaft holder further includes a tapered surface extending from the forward end to the rearward end. The tapered surface includes a surface feature for inducing turbulent flow to water passing thereover.

Abstract: A passively stable personal hydrofoil watercraft that has a floation device, wherein a user can ride in a prone, kneeling, or standing position. The watercraft includes a strut having an upper end interconnected with the flotation device and lower end connected with a hydrofoil. The hydrofoil greatly reduces the power required to travel at higher speed. The watercraft also includes a propulsion system connected to the hydrofoil. Both longitudinal and directional control of the watercraft is via weight shift, eliminating the need of any movable surfaces. The floation device, strut, and hydrofoil may be permanently interconnected or may be detachable.

Abstract: A displace hull with a shape that is both laterally symmetric and fore-to-aft symmetric is disclosed. The hull includes a pair of channels that help to manage a flow of water around the hull. The hull also includes sponsons and propellers that are located amidships on the port and starboard sides.

Abstract: A guard for protecting wildlife is mounted on an outboard motor having a propeller and keel below an anti-ventilation plate. The guard has a spaced pair of bars each with an upper section, a lower section and between them a midsection. The upper sections of the bars can be attached to opposite sides of the anti-ventilation plate in order to position the lower sections below the propeller and keel. The lower sections have a smooth, projection-free streamline for avoiding snagging on sea weed.

Abstract: A drive system for a watercraft has a water inlet opening, a water outlet opening, and a fin system. A propellerless pre-nozzle for the drive system is configured rotationally asymmetrically in order to further improve the drive efficiency.

Abstract: A marine propulsion system for shallow waters, swamps, savannahs and the like includes a rotating propeller shaft supporting a propeller. An anti-cavitation body defines a partial cylinder having a longitudinal axis adjacent to the propeller. The propeller generates a vacuum between the anti-cavitation body and a surface of a water body. First and second wings adjacent to edges of the anti-cavitation body are generally planar and operatively angled towards the bottom of a water body. The first and second wings are adjusted to run below the water body surface and seal the anti-cavitation body to maintain generated vacuum. A first thread is cut in a first helical direction at an end of the rotating propeller shaft adjacent the propeller, and slightly more distal therefrom a second thread is cut in a second helical direction opposed to the first thread helical direction. The second thread drives matter away from the bearing.

Abstract: An all-speed-range propeller having stern fins comprises an all-speed-range propeller installed on a propelling shaft of a boat, and a plurality of stern fins installed between the all-speed-range propeller and a hull of the boat. When the all-speed-range propeller having stern fins is applied to the oblique boat on which the propelling shaft is disposed obliquely, the stern fins directly guide the water flow toward the all-speed-range propeller, so that the uneven inflow caused by the obliquely-designed propelling shaft can be conquered to promote the operating efficiency of the all-speed-range propeller.

Abstract: A stern bracket for mounting a drive unit to a watercraft including a transom. The drive unit is pivotable with respect to the stern bracket about a tilt axis. The stern bracket includes a support member for fixing the drive unit to the transom and a water deflector. The water deflector comprises a mounting bracket attached to the support member and a deflection plate connected to the mounting bracket. The deflection plate, disposed at a vertical position lower than the tilt axis, extends between the transom and the drive unit mounted to the stern bracket mounted to the transom. A left deflection wing, connected to at least one of the deflection plate and the mounting bracket, extends downward and laterally outward therefrom. A right deflection wing, connected to at least one of the deflection plate and the mounting bracket, extends downward and laterally outward therefrom. A watercraft is also disclosed.

Abstract: An aeration control system and method for a marine vessel. The system includes a valve configured to be coupled to an aeration conduit of a marine vessel. The valve is configured to be responsive to a valve control signal having a first value so as to be open and to provide air to the aeration conduit, and the valve configured to be responsive to the valve control signal having a second value so as to be closed and not provide air to the aeration conduit. The aeration control system also includes a control device, electrically coupled to the valve, that provides the valve control signal to the valve.

Abstract: The invention provides a powered water sports board (10) which includes a motor (16) and a power supply (18), both of which are mounted inside a cavity (20) formed inside an elongate buoyant body (12) of the powered water sports board, and a propeller (36) which is capable of being driven by the motor (16) and which is housed inside a fin (14) of the elongate buoyant body (12) thereby to shield the propeller.

Abstract: A powerboat with a rooster tail depressor (RTD) includes a hull, a propulsion subassembly on the hull, and a rooster-tail-suppressing canopy on the stern that includes a downwardly facing surface no less than six inches above the dynamic water line of the stern where it functions to suppress the powerboat rooster tail for radar signature reduction and increased propulsion efficiency. Various embodiments include one or more of (i) a canopy having a downwardly facing surface that is arched (either curved or faceted), (ii) lift-to-drag ratio enhancing steps in the downwardly facing surface of the canopy, (iii) a rooster-tail-suppressing subassembly configured to enable articulation of the canopy in yaw and in trim, and (iv) operator-controlled port and starboard venting arrangements on the canopy that result in desired laterally directed thrust for enhanced maneuverability.

Abstract: A prop shaft holder for an outboard motor includes a forward end for engaging a gear casing of the outboard motor and a rearward end axially spaced apart from the forward end. The rearward end includes an inner radial surface for engaging an outer radial surface of a propeller. The prop shaft holder further includes a tapered surface extending from the forward end to the rearward end. The tapered surface includes a surface feature for inducing turbulent flow to water passing thereover.

Abstract: Marine tunnel thruster includes a duct, within which at least a propeller is fitted that is operatively connected to a rotational drive system. The duct is composed of three sections, which include a first central section and two end sections. The first central section has a specific length and a specific diameter, while the two end sections have a specific length and a specific diameter greater than the diameter of the central section.

Abstract: An outboard marine drive with an engine is described. The marine drive can include a drive housing with an upper drive housing and lower drive housing. The drive housing can be attached to a transom of a marine craft. An upper gear drive assembly can be located in the upper drive housing. A transmission can be provided with the upper gear drive assembly in the upper drive housing. In addition, a lower gear drive assembly can be located in the lower drive housing and coupled to the upper gear drive assembly. A propeller shaft may also be coupled to the lower gear drive assembly.

Abstract: An assembly (10) is provided for mounting a hydrofoil, trolling plate or trolling motor (or other accessory) on the anti-ventilation plate (14) of a sterndrive or outboard motor (16) without the need to modify the plate or motor. The assembly (10) has lower and upper elements (20, 22) which are secured about the plate (14) by bolts (34). The upper element (22) has a bolt pattern (40) to mount the hydrofoil or other device. A catch (60, 88, 88a, 88b, 88c, 88d) mounted on the lower element (20) can be engaged in the trim tab or anode recess. Grip devices (50) can be mounted on the lower element (20) that are adjusted to grip the edges of the plate (14).

Abstract: A water flow limiting system for a boat including a water flow limiting plate, a coupling mechanism and a controllable bite ram. The water flow limiting plate is positioned below the propeller shaft and forward of the propeller for limiting water flow to the propeller. The coupling mechanism is provided for steering the water flow limiting plate relative to the boat. The coupling mechanism may be a mounting mechanism which maintains the flow limiting plate generally aligned with the propeller shaft, or it may be a steering mechanism which steers the flow limiting plate relative to the propeller shaft. The controllable bite ram controls vertical displacement of the flow limiting plate relative to the propeller shaft. A propeller guard system positioned above the water flow limiting plate may be included. A cooling coil may be affixed to the water flow limiting plate.

Abstract: An outboard motor for a marine vessel application, and related methods of making and operating same, are disclosed herein. In at least one embodiment, the outboard motor includes a horizontal-crankshaft engine in an upper portion of the outboard motor, positioned substantially positioned above a trimming axis of the outboard motor. In at least another embodiment, first, second and third transmission devices are employed to transmit rotational power from the engine to one or more propellers at a lower portion of the outboard motor. In at least a further embodiment, the outboard motor is made to include a rigid interior assembly formed by the engine, multiple transmission devices, and a further structural component. In further embodiments, the outboard motor includes numerous cooling, exhaust, and/or oil system components, as well as other transmission features.

Abstract: A marine drive has a lower drive unit including a gearcase with a vertical strut having a lower horizontal torpedo with an aft propeller. An anti-ventilation plate on the strut is spaced above the torpedo. A spray shield plate on the strut is spaced above the torpedo and below the anti-ventilation plate.

Abstract: An outboard motor for a marine vessel application, and related methods of making and operating same, are disclosed herein. In at least one embodiment, the outboard motor includes a horizontal-crankshaft engine in an upper portion of the outboard motor, positioned substantially positioned above a trimming axis of the outboard motor. In at least another embodiment, first, second and third transmission devices are employed to transmit rotational power from the engine to one or more propellers at a lower portion of the outboard motor. In at least a further embodiment, the outboard motor is made to include a rigid interior assembly formed by the engine, multiple transmission devices, and a further structural component. In further embodiments, the outboard motor includes numerous cooling, exhaust, and/or oil system components, as well as other transmission features.

Abstract: A stern structure of a ship includes a plurality of propellers, a plurality of propeller shafts and a stern structural body. A plurality of propeller shaft tubes is provided correspondingly to the plurality of propellers, and the plurality of propeller shafts connected to the plurality of propellers is inserted into the plurality of propeller shaft tubes. The stern structural body extends backwardly from the stern body, spreads externally with respect to a ship body center line C, and contains portions of the plurality of propeller shafts extending backwardly from the stern body. An inner side of the stern structural body is equivalent to an interior portion of a ship body. The stern structural body supports the plurality of propeller shaft tubes in the interior portion of the ship body.

Abstract: A propeller drive for boats features a transition cone between the gearbox housing and the propeller hub(s). The propeller hub (that is closest to the gearbox housing) is smaller in cross-sectional dimension than the gearbox housing. The dimension of the front end of the transition cone corresponds to the cross-sectional dimension of the gearbox housing, and the dimension of the rear end of the transition cone corresponds to the cross-section dimension of the (closest) propeller hub. The transition cone has a bulging shoulder between the front and rear ends, the largest peripheral cross-sectional dimension of which is greater than the cross-sectional dimension of the front of the transition cone.

Abstract: A device for reducing the drive power requirement of a ship and even for not very quick ships of all types, in particular for slow, wide ships, such as tankers, bulkers and tugboats, and for improving the propeller blower stream as well as for producing a pretwist includes a front nozzle fixedly installed on the hull with fins or hydrofoils placed in the inner space thereof.

Abstract: A twin-skeg ship that allows for an improvement in propulsion performance (propulsion efficiency). A twin-skeg ship has a pair of left and right skegs on the bottom of a stern has reaction fins, each comprising a plurality of fins extending radially from a bossing fixed to a stern frame provided at a rear end of the skeg, or from a fin boss provided on the bossing, in a range where a flow immediately in front of a propeller attached to the skeg with a propeller shaft therebetween has a component in the same direction as a rotational direction of the propeller.

Abstract: A drive system for a watercraft has a water inlet opening, a water outlet opening, and a fin system. A propellerless pre-nozzle for the drive system is configured rotationally asymmetrically in order to further improve the drive efficiency.

Abstract: A hydrofoil boat stabilizer having a cross-sectional area with the configuration of a true hydrofoil is provided. The hydrofoil includes a slip-on yoke designed to compressively fit on a cavitation plate of a boat motor lower drive unit. The wings of the hydrofoil include at least one angle of attack, and preferably, a plurality of angles of attack. The hydrofoil is shaped to reduced drag and minimize cavitation. A low-drag surface is included on at least a portion of the outer surface of the hydrofoil.

Abstract: The invention provides a powered water sports board (10) which includes a motor (16) and a power supply (18), both of which are mounted inside a cavity (20) formed inside an elongate buoyant body (12) of the powered water sports board, and a propeller (36) which is capable of being driven by the motor (16) and which is housed inside a fin (14) of the elongate buoyant body (12) thereby to shield the propeller.

Abstract: A boat propulsion engine includes a buoyant member (20) disposed on a case body that houses a drive shaft (47) in order to lift the stern. The buoyant member has a lower surface (32) that slopes downward in the rearward direction.

Abstract: The main propulsion and drive system of a merchant vessel such as a freighter or tank vessel, or a military vessel is supplemented by an auxiliary propulsion and drive system that includes at least one, but preferably a pair of auxiliary propellers that flank the main propeller at port and starboard positions and each of which are attached via a drive shaft through a gear train, which can optionally include a clutch mechanism, to an auxiliary motor or motors. In order to reduce the drag when the main propeller is disabled, segments of a wake field modifying propeller duct are mounted for repositioning to form at least a partial housing or cowling that diverts the water over the exterior surface of the duct and minimizes contact with the stationary blades of the main propeller as the vessel moves through the sea when powered by the auxiliary propulsion system.

Abstract: A device for reducing the power demand for the propulsion of a ship, and for broad-built or non-broad-built not-very-fast ships of any type which is affixed to the hull at a short distance upstream of the propeller, comprises a fore-nozzle with fins or hydrofoils that are arranged within the fore-nozzle, wherein the fore-nozzle, at the top, can be tilted forwards by up to 8°, on a horizontal transverse axis that extends through the centre of the fore-nozzle.

Abstract: The invention as disclosed is an apparatus that controls the wake of stator blades on an underwater vehicle. The apparatus comprises one or more stator blades each with a movable trailing edge that when actuated in a controlled manner produces a periodic flapping motion upstream of a propulsion rotor. The controlled periodic flapping of the trailing edge the fills the stator blade wake enough to overcome the stator blade's own drag and fill its wake deficit. This has the effect of reducing the blade rate tonal noise of the propulsion rotor.

Abstract: An assembly (10) is provided for mounting a hydrofoil, trolling plate or trolling motor (or other accessory) on the anti-ventilation plate (14) of a sterndrive or outboard motor (16) without the need to modify the plate or motor. The assembly (10) has lower and upper elements (20, 22) which are secured about the plate (14) by bolts (34). The upper element (22) has a bolt pattern (40) to mount the hydrofoil or other device. Grip devices (50) can be mounted on the lower element (20) that are adjusted to grip the edges of the plate (14). A catch (60) mounted on the lower element (20) can be engaged in the trim tab or anode recess.

Abstract: A marine drive system (1) with a partially submerged propeller located at the transom of a boat comprising, for each propeller (2), a forward-opened shroud (20), positioned above the propeller (2), such as to define, between it and the water level, a channel (23) extending longitudinally and having, at the propeller (2), a cross-section whose area decreases from the transom (30).

Abstract: A boat propulsion engine (1) comprises a main body (4) that extends substantially vertically in relation to a hull (Si), a lift generator (20) disposed in a rear portion of the main body (4), and supporting bodies (24) that support the lift generator (20) on the main body (4). The lift generator (20) has a surface (21g, 21h) that extends transversely relative to the main body (4) and that is located behind at least the main body (4). The supporting bodies (24) extend backward from the main body (4) to the lift generator (20) in a single vertical direction relative to a surface (21g, 21h) of the lift generator (20).