Abstract: The present invention relates to a system and a method for control and reduction of the RPM of at least one main engine of a vessel, which main engine drives at least one first propeller for propulsion, which first propeller is pitch-regulated, which second thruster propeller is pitch-regulated. It is the object of the invention to reduce the RPM of one ore more main engines of a vessel and by increasing the pitch of the propellers to maintain constant propulsion, and by reducing the RPM of the main engines to re-duce the fuel consumption and in this way reduce pollution. The object can be fulfilled by a system analysing the RPM and pitch of the first main shaft propeller, which system analyses the RPM and the pitch of the second thruster propeller, which system based on said analyses performs downward regulation of the RPM of the main engine.

Abstract: A system that controls speed of a marine vessel includes first and second propulsion devices that produce first and second thrusts to propel the marine vessel. A control circuit controls orientation of the propulsion devices between an aligned position in which the thrusts are parallel and an unaligned position in which the thrusts are non-parallel. A first user input device is moveable between a neutral position and a non-neutral detent position. When the first user input device is in the detent position and the propulsion devices are in the aligned position, the thrusts propel the marine vessel in a desired direction at a first speed. When a second user input device is actuated while the first user input device is in the detent position, the propulsion devices move into the unaligned position and propel the marine vessel in the desired direction at a second, decreased speed without altering the thrusts.

Abstract: An outer mounting body is made of semi-soft material having a primarily flat planar shape formed with an upper housing portion, and an outer flange portion having a planar upper surface tapering from the housing portion to outer peripheral edges of the mounting body and adapted to be mounted to flexible or curved surfaces such as those of an inflatable surfboard. An inner mounting insert made of rigid material is molded within the outer mounting body and has an upper recess for sturdily mounting an object such as a surfboard fin. The inner mounting insert may be formed asymmetric for reversibly mounting left and right side fins near the edges of a surfboard.

Abstract: A watercraft has a hull with a first end and a second end and is equipped at its second end with a propulsion arrangement that includes at least three propulsion devices each provided with a propeller. A majority of the propulsion devices are rudder propeller devices, and the propeller of at least one of the propulsion devices is at a first distance from the second end of the hull and the propeller of at least another one of the propulsion devices is at a second distance, greater than the first distance, from the second end of the hull. In ice conditions the watercraft is operated with the second end ahead, so that at least one propeller at the first distance from the second end of the hull breaks ice and at least one propeller at the second distance from the second end of the hull moves disintegrated ice or ice chunks away from the ice build-up.

Abstract: Boat (10) comprising a steering and propelling unit comprising at least one driving shaft (11, 11?) passing in an opening of the transom (12) for transmitting the motion from a motor to at least one propeller (21, 21?), at least one steering (14) provided at the top with at least one rotation pin (13), and a through-hull support (100) able to be associated with the opening and equipped with a plate portion (101) able to be fixed on the outside to the hull (12) of the boat (10) and with a through-hull tubular portion (102) for support of the at least one driving shaft (11, 11?), in which the through-hull support (100) also comprises at least one bush (103) passing through the plate portion (101) to support, in a rotary manner, the pin (13) bearing the steering (14) and in which the wall (12) of the hull where the passage opening of the at least one driving shaft (11, 11?) is formed is inclined from the top to the bottom in the direction of the stem of the boat (10).

Abstract: A propeller drive assembly, for steering and driving a ship (1), comprises a drive motor (2) and a transmission housing (4) secured to a ship hull and a control housing (7) secured to an exterior surface of the hull. The control housing (7) comprises a propeller (8) supported on a driven shaft (6) and the control housing (7) is pivotably coupled, via a steering shaft (10), to the transmission housing (4) for steering the ship (1). A transmission output shaft (5) is connected with the driven shaft (6) and a lubricant circuit of the transmission housing (4) is separate from a lubricant circuit of the control housing (7). At least one sealing element is provided, in a region of a shaft passage of the transmission output shaft (5) and in a region of a shaft passage of the steering shaft (10), for mutually sealing the transmission housing lubricant circuit and the control housing lubricant circuit.

Abstract: A propulsor and control system for an underwater vehicle having annular fore and aft circumferential shrouds surrounding the hull. The fore and aft circumferential shrouds form respective fore and aft circumferential shroud gaps between the fore and aft circumferential shrouds and the hull. Fore and aft propulsor blades are situated substantially or completely within the fore and aft circumferential shroud gaps; the blades counter-rotate in one preferred embodiment. The fore or aft circumferential ring propulsors can have front control vanes located in front of the respective propulsors blade sets, and back control vanes located behind the respective propulsors to control the direction of the flow of water in order to maneuver the underwater vehicle.

Abstract: A marine propulsion assembly comprises or consists of a marine engine, a pair of parallel laterally spaced propeller shafts and a pair of marine propellers with one of the propeller fixed to each of the shafts for rotation. Each of the propellers includes a hub and four equally spaced blades and wherein the hub has a forward portion having the shape of a frustum of a cone with a decreasing radius from a forward edge thereof to the middle of the hub and a rear or second continuous portion having the shape of a frustum of a cone with an increasing radius from the middle of the hub to the rear of the hub. The bases or larger ends of the frustums are of equal size as are the tops of the frustums.

Abstract: The invention relates to a method for improving the propulsion efficiency of vessels. The improvement is obtained by utilizing wave induced variations in propeller inflow, i.e. the speed of water flowing towards the propeller. The wave induced water speed variation is used to calculate the propeller speed in a way so that the propeller speed is optimal with respect to the total propulsion efficiency. The optimal propeller speed is determined by solving an optimization problem formulated as the maximization of the ratio of energy delivered by the propeller and the energy delivered to the propeller. The method may be used for vessels with one or more propellers.

Abstract: A torque transmitting device and related a marine propulsion system include an adapter that comprises a first portion shaped to engage in torque-transmitting relation with a propulsor shaft of the marine propulsion system so that rotation of the propulsor shaft about the axis of rotation causes synchronous rotation of the first portion about the axis of rotation. A second portion is shaped to engage in torque-transmitting relation with a propulsor hub of the marine propulsion system. The second portion is connected to the first portion by a plurality of elongated torsional members that are integrally attached to at least one of the first and second portions. The elongated torsional members are resilient so as to allow the first portion and second portion to rotate relative to each other about the axis of rotation.

Abstract: Boat (10) comprising a steering and propelling unit comprising at least one driving shaft (11, 11?) passing in an opening of the transom (12) for transmitting the motion from a motor to at least one propeller (21, 21?), at least one steering (14) provided at the top with at least one rotation pin (13), and a through-hull support (100) able to be associated with the opening and equipped with a plate portion (101) able to be fixed on the outside to the hull (12) of the boat (10) and with a through-hull tubular portion (102) for support of the at least one driving shaft (11, 11?), in which the through-hull support (100) also comprises at least one bush (103) passing through the plate portion (101) to support, in a rotary manner, the pin (13) bearing the steering (14) and in which the wall (12) of the hull where the passage opening of the at least one driving shaft (11, 11?) is formed is inclined from the top to the bottom in the direction of the stem of the boat (10).

Abstract: A propulsion system of displacement or semi-displacement ships, includes one or more propellers of semi-submerged type, arranged with a partial immersion of the sole bottom blades and with the top blades emerged, regardless of the state of motion and the trim of the craft. The propulsion system allows, employed power being equal, a higher propulsion efficiency and allows to keep the driveline of the propellers entirely above water level, wherein the semi-submerged propellers are arranged at the transom, the ratio of diameter (D) or sum of diameters (Np×D) of the semi-submerged propellers to craft width (L) at the water line (3) is greater than 0.50.

Abstract: A propulsion device of a ship is provided with a port side propeller, a starboard side propeller, a port side propeller axis and a starboard side propeller axis. The port side propeller axis extends backwardly from the hull stern and is connected with the port side propeller. The starboard side propeller axis extends backwardly from the hull stern and is connected with the starboard side propeller. When the propeller diameters of the port side propeller and the starboard side propeller are Dp, the distance between a propeller wing tip of the port side propeller and a propeller wing tip of the starboard side propeller is equal to or more than 0 and equal to or smaller than 0.5 Dp.

Abstract: The invention relates to a propeller pod (14) having a body (16) which has a shaft (18) for attachment to a vehicle (10), in particular to a watercraft, wherein the shaft (18) extends along a shaft axis (AS) and has at least one cross section (Q) with a chord (S), and (b) at least one propeller shaft (20, 24) for attachment of a propeller (22), (c) wherein the chord (S) runs at a direction angle (?) with respect to a propeller rotation axis (AP) of the propeller shaft (20, 24). The invention provides that the direction angle (?) changes, at least in places, with the distance (r) from the propeller rotation axis (AP).

Abstract: The instant invention is a shroud/keel/rudder combination for use on a engine driven marine vessel having a vented tunnel propulsion system. The combination produces acceptable acceleration, minimal loss of speed, resistance to weed entanglement and optimized steering, in both forward and reverse, especially when used with surface piercing propellers.

Abstract: A water propulsion unit having an intake housing, a pump housing and an outlet with two spaced apart counter rotating impellers being located in the pump housing. The impeller blades on one impeller have an opposite pitch to the blades of the second impeller. The impellers are configured so that one of the impellers will impart less energy to the water as it passes the blades of the impeller than the second impeller.

Abstract: A propeller thrust transmission device includes a taper portion of a propeller shaft that is fitted in a spacer divided into a first half and a second half. A thrust force acting on a propeller is received by the taper portion of the propeller shaft through the spacer. The first half includes a taper hole having an inner surface which corresponds in shape to an outer surface of the taper portion and in which the taper portion is fitted. The second half has a smaller diameter portion extending from one side of a ring-shaped wall portion closer to the propeller and fitted in a hole of an attachment device spaced from the propeller shaft, and a larger diameter portion extending from the other side of the ring-shaped wall portion and fitted on an outer peripheral surface of the first half.

Abstract: An enhanced counter-rotating electric motor and an associate propulsion system for use with a water-vehicle includes a motor housing, a stator within the housing that rotates about a central axis in one direction, an armature within the stator that rotates about the central axis in an opposite direction from the stator, a first axel that is secured to the stator and extends out from the housing, a second axel that is secured to the armature and extends out from the housing, water-tight rotational seals about each of the two axels, a centrifugal-force-balancing electrical connection mechanism that supplies functioning electrical communication between the motor and external electrical circuitry while operating the motor, and a propeller secured to each said axel.

Abstract: A propulsion system of displacement or semi-displacement ships, includes one or more propellers of semi-submerged type, arranged with a partial immersion of the sole bottom blades and with the top blades emerged, regardless of the state of motion and the trim of the craft. The propulsion system allows, employed power being equal, a higher propulsion efficiency and allows to keep the driveline of the propellers entirely above water level, wherein the semi-submerged propellers are arranged at the transom, the ratio of diameter (D) or sum of diameters (Np×D) of the semi-submerged propellers to craft width (L) at the water line (3) is greater than 0.50.

Abstract: Disclosed is a floating system. The floating system comprises a floating body, a first propeller and a second propeller. The first propeller is pivotally secured to the floating body. The second propeller is pivotally secured to the floating body and distanced from the first propeller in a first direction and in a second direction perpendicular to the first direction. The first and second directions are generally parallel to a surface of water on which the floating system floats.

Abstract: A ship is disclosed which is driven by inboard engines with propellers and by water jets producing jets of water. The inboard engines are embodied in the form of electric motors and the water jets are used underneath the bottom of the ship. The electric inboard engines are accommodated in skegs on the underside of the ship. A flow channel is formed between the skegs for the jets of water emitted by the water jets.

Abstract: A boat drive system is provided for a power boat which includes an engine having a drive shaft, connected to a pair of propeller shafts. The drive system includes a primary gearbox and opposed outboard gearboxes. The primary gearbox includes a housing and a gear arrangement connected to the engine shaft and the outboard gearboxes, which are connected to the primary gearbox by a transverse shaft, include a housing and a gear arrangement connected to associated propeller shafts. A cooling system is provided including a cooling pad for each gearbox. A support system is provided for each outboard gearbox including a cradle connected to the bearing points on the hull. The engine includes an adapter plate attached to the primary gearbox for movement of the primary gearbox with the engine. In a modified drive system only one outboard gearbox is used in conjunction with a single engine. In another modified drive system a single engine and propeller are used in conjunction with a gearbox having a take-off shaft.

Abstract: A water propulsion unit having an intake housing, a pump housing and an outlet with two spaced apart counter rotating impellers being located in the pump housing. The impeller blades on one impeller have an opposite pitch to the blades of the second impeller. The impellers are configured so that one of the impellers will impart less energy to the water as it passes the blades of the impeller than the second impeller.

Abstract: A drive shaft supporting structure for a small boat is provided which permits simplification of a hull and for which manufacturing productivity is increased. The drive shaft supporting structure includes a shaft-supporting member for rotatably supporting a drive shaft inside of a hull, and an elongate cylindrical sleeve. The cylindrical sleeve is arranged between the shaft-supporting member and a hull opening which permits penetration of the drive shaft through the hull. The drive shaft supporting structure is configured in such a manner that a front end portion of the cylindrical sleeve is connected to the shaft-supporting member and a rear end portion of the cylindrical sleeve is connected to the hull opening.

Abstract: A ship hull includes at least one float (10) and a centre of buoyancy (CB) situated behind the centre of flotation (CF), the distance between the centre of buoyancy and centre of flotation is greater by 5% than the waterline length L of the hull.

Abstract: In an outboard drive or an inboard-outboard drive, power generated by a single engine is transmitted in left and right directions from a main drive shaft, thereby finally causing left and right propellers to be rotated, the left and right propellers being arranged about the main drive shaft so as to be spaced apart from the main drive shaft at approximately equal distances from the main drive shaft and facing a travel direction of a marine vessel, the outboard drive or inboard-outboard drive being provided with left and right shift cam assemblies for causing rotation situations of the propellers to be controlled dependently from each other, the rotation situations including normal rotation, reverse rotation and non-rotation situations of the propellers.

Abstract: The invention relates to a watercraft, particularly a river boat, with a hull for receiving useful devices and with propulsion units for generating a driving force and which are located on the hull. The watercraft according to the invention is characterized in that guiding elements are provided in the bow area on the underside of the hull, which have a vertical, forwardly tapering wedge shape, that the propulsion units in the bow area are set back from the wedge-shaped guiding elements, that between the guiding elements is provided a partial area of the hull constructed in the form of a horizontal wedge and that the propulsion units are pivotably mounted.

Abstract: A boat hull comprises a hull body having two lateral flanks linked by a bottom surface, and at least two propulsion compartments provided in two bulges protruding below the bottom surface of the hull body. Each propulsion compartment lodges a propulsion engine located below the bottom surface of the hull body. The propulsion engines are located at the deepest position in the hull and below the water plane.

Abstract: A method for controlling the movement of a marine vessel comprises steps that rotate two marine propulsion devices about their respective axes in order to increase the hydrodynamic resistance of the marine propulsion devices as they move through the water with the marine vessel. This increased resistance exerts a braking thrust on the marine vessel. Various techniques and procedures can be used to determine the absolute magnitudes of the angular magnitudes by which the marine propulsion devices are rotated.

Abstract: A bow mounted vessel propulsion system is designed to exploit the characteristics of a self-producing vessel lubricating boundary layer of air or air bubbles formed during water surface interaction by the vessel's hull during vessel movement. This boundary layer of air/air bubbles will be produced at the bow of the vessel and, during forward motion, is superimposed upon the surface of the water as the vessel's hull passes over, reducing the frictional drag of the hull as it moves across and through the water. The system has a propulsion means such as a water surface-piercing propeller or water jet nozzles, which will propel the vessel forward and, at the same time, by action of propeller rotation (drawing air into and intermixing) in the water or water jet movement, will create the air bubbles which produce the hull-lubricating phenomenon. The hull is a substantially flat-bottomed planning hull with two linear rails on each lengthwise outer edge of the bottom surface of the hull.

Abstract: An efficient double-ended watercraft is disclosed that comprises four low-Froude number hulls: two forward, two aft, two on the port side, and two on the starboard. Each hull comprises an independent engine that drives a propeller shaft and propeller that is located amidships. The propeller shafts on the starboard are collinear, as are the propeller shafts on the port. The propellers on the starboard are near each other and counter rotate, as do the propellers on the port. The propellers are variable-pitch propellers. When the ferry is changes from moving forward to moving in reverse and from reverse to forward, the propellers on the starboard exchange pitch. This enables the ferry to move as efficiently in reverse as it does when forward. The propellers on the port also exchange pitch when changing from moving forward to moving in reverse and from reverse to forward.

Abstract: The dual propeller surface drive propulsion system for boats is a combined propulsion and steering system for vessels with inboard engines comprising an enclosed thrust bearing assembly mounted to the transom of the vessel, a transom box mounted to the transom of the vessel that encompasses the thrust bearing assembly, an articulated outdrive pivotally connected to the transom box, a gearbox contained within the articulated outdrive, two counter rotating propeller shafts equipped with surface-piercing propellers and a steerable rudder system. Counter-rotating propellers reduce propeller-induced torque. By combining an articulated outdrive with a steerable rudder greater maneuverability of the vessel is achieved.

Abstract: Hull and propeller arrangement for a surface watercraft (1), provided with at least one propeller (3), in addition to which the propeller (3), at high speeds of the watercraft, is surface-piercing, and the propeller (3) is arranged in such a manner that only the propeller blades (11) or parts thereof are submerged in the water at high speeds of the watercraft (1), in addition to which the hull (2) is provided with at least one streamlined projecting part (4) extends essentially in the longitudinal direction of the hull (2), the projecting part (4), in terms of its outer shape, has, at its aft end (6), an end edge (15) which, at least in part, extends essentially transversely to the longitudinal direction of the projecting part (4), the propeller (3) is locaded immediately astern of the end edge (15), and a part of the propeller, in the radial direction, extends beyond the delimiting surfaces of the projecting part (4).

Abstract: A wake adapted propeller drive mechanism delays or reduces cavitation or stall in a propeller drive mechanism mounted for rotation at the stern of a hull so as to be rotatable in a wake produced by forward motion of the hull through the water. The wake adapted propeller drive mechanism skews the drive shaft of the propeller sideways of the hull in a horizontal plane so as to adjust the angles of attack of the propeller to maintain the angles of attack below that which could produce cavitation or cavitation noise.

Abstract: In a watercraft drive for a watercraft having front and rear propellers respectively mounted on a drive shaft in coaxial longitudinally displaced relationship, each of said propellers having at least two blades, the front and rear propellers having equal diameters and being driven at like rotational velocities. The central portion of the rear propeller up to a diameter equal to the diameter of the water jet arriving at the rear propeller, which due to the action of the front propeller has a contracted cross section, is designed to optimize the jet energy exiting the front propeller. The rear propeller has an annular area extending from the central portion to the outer circumference of the rear propeller, being designed with the same design as characterizes the front propeller. The annular area of the rear propeller receives a flow of surrounding ambient water.

Abstract: Boat propeller drive with an underwater housing which is connected in a fixed manner to a boat hull and has tractor propellers arranged on that side of the housing facing ahead. In the rear edge of the underwater housing, a rudder blade is mounted for pivoting about a vertical rudder axis.

Abstract: An aquatic shredder includes a watercraft and a pair of large, high speed propellers mounted at both the bow and stern ends of the watercraft. The propellers are configured to not only propel the watercraft through the water but also to chop vegetation at or near the water surface. Moreover, the bow propellers are similar in construction to the stern propellers so that they similarly effect comminution of the vegetation and propulsion of the watercraft. In particular, each pair of propellers extends completely across the width of the watercraft and projects laterally outward beyond the port and starboard sides of the watercraft. Each pair of propellers is preferably supported by a swingable frame that permits the user to raise and lower the propellers as desired. To enhance the cutting action of the propellers, the blades of the propellers may be provided with fore and aft extending knives.

Abstract: The invention relates to a pod unit comprising a pod housing (1) and an assembly unit (6), a so called seating, for the pod housing (1), wherein the seating (6) comprises a lower portion (6A) and an upper portion (6F) as well as a base (15) for the installation of said pod housing (1) which comprises a lower casing portion (1A) for the accommodation of a propulsion unit (2, 3, 4), an intermediate portion (1B) comprising air ducts (9, 10), and an upper portion (13), which is fixedly connected to a steering engine (14, 18, 19), with a gear ring (14) to be fixed at said base (15). The invention is characterised therein that a cooling system comprising at least a fan (7) is mounted within the seating (6).

Abstract: A propeller attachment is disclosed including a body, the body including an anodic material, at least one projection projecting from the body, and a fastener coupled to the body. An anode is also disclosed including an annular body constructed from an anodic material, a fastener disposed centrally in the annular body, and at least one extension coupled to the annular body, the at least one extension is configured to allow for gripping of the anode. A fastener for coupling a propeller to a drive shaft of a lower unit is disclosed including a fastening portion configured to threadably engage the drive shaft and retain the propeller. The fastener further includes an anodic portion disposed around the fastening portion. The anodic portion is shaped to form at least one grip, and the anodic portion preferentially corrodes to prevent corrosion of the lower unit.

Abstract: An aquatic shredder includes a watercraft and a pair of large, high speed propellers mounted at both the bow and stern ends of the watercraft. The propellers are configured to not only propel the watercraft through the water but also to chop vegetation at or near the water surface. Moreover, the bow propellers are similar in construction to the stern propellers so that they similarly effect comminution of the vegetation and propulsion of the watercraft. In particular, each pair of propellers extends completely across the width of the watercraft and projects laterally outward beyond the port and starboard sides of the watercraft. Each pair of propellers is preferably supported by a swingable frame that permits the user to raise and lower the propellers as desired. To enhance the cutting action of the propellers, the blades of the propellers may be provided with fore and aft extending knives.

Abstract: A water jet apparatus with counter-rotating impellers for propelling a boat. The impellers are coupled by an assembly comprising an impeller shaft secured to a first impeller and a gear train coupling the impeller shaft to a second impeller for counter-rotation. Preferably the gear train comprises one beveled gear secured to the impeller shaft, another beveled gear secured to the second impeller, and a beveled pinion meshed with the first and second beveled gears. The counter-rotating impellers can be driven by a drive shaft coupled to the first impeller for boats having an inboard motor or by a drive shaft coupled to the pinion for boats having an outboard motor.

Abstract: A marine propulsion assembly comprises a drive shaft, a first propeller fixed to the drive shaft and turnable therewith in a first direction, an annular array of gear teeth disposed on the first propeller and turnable therewith, a second propeller aligned with the first propeller, and an annular array of gear teeth disposed on the second propeller. Bevel gears are disposed between the first and second propellers and engaged with the first and second annular arrays of gear teeth. The bevel gears transmit rotation of the first propeller to the second propeller, such that the second propeller turns in an opposite direction relative to the first propeller.

Abstract: An impeller for a marine waterjet propulsion system has blades that are configured to reduce cavitation, vibration, noise and physical damage to the major components of the propulsion system or host vessel of installation. The leading edge of each blade of the impeller is skewed forwardly over at least the outer 70% of its span, the forward skew being maximum at the tip and being not less than 35.degree.. The impeller has a blade area ratio of not less than 1.5. The chord lengths of each blade increase progressively from the point of minimum skew to the tip, resulting in reduced loading in the cavitation critical region. A partial or full tip band may be affixed to the blade tips.

Abstract: An aquatic vegetation shredder includes a double hull watercraft, with a space being defined between the hulls. The machine also includes an aquatic vegetation shredding assembly mounted to the watercraft adjacent the bow end, and a pair of propellers rotatably mounted to the watercraft adjacent the stem end. The propellers are configured to propel the watercraft through the water and draw water through the space defined between the hulls. Such a design causes the vegetation to be drawn toward the vegetation shredding assembly, while preventing the shredded vegetation from accumulating at the assembly; thereby eliminating the need for feeding devices for feeding the vegetation to the shredding assembly and discharge chutes for discharging the shredded vegetation away from the assembly. In addition, the propellers are operable to shred vegetation, thereby ensuring destruction of vegetation below the water surface and further commination of vegetation received from the shredding assembly.

Abstract: A propulsion system and power plant for boats, preferably for naval vessels, consisting of two Diesel engines, a gas turbine and two drive shafts located next to one another with propellers, is characterized by the fact that there is also a water jet or hydrojet propulsion unit (1) between the two drive shafts (2, 3) which are located next to one another with propellers (4, 5), that the Diesel engines (6,7) are used to drive the two propellers (4, 5), that the water jet propulsion (1) is provided by the gas turbine (8) and that the gas turbine (8) is located between the Diesel engines (6, 7) and the stern of the vessel (9).

Abstract: Ferries in particular may have identical drives at the bow and stern in order to avoid turning the ship when the direction of travel changes. Normally, when travelling, the rotation speed of the front screw is selected to be lower than the rotation speed of the rear screw. According to the invention, minimum-value regulation of the sum of the recorded real power levels of both drive systems is used for efficiency optimization. In the case of the associated arrangement, a regulator (10) is provided, with the real power levels of both drives as input variables, that rotation speed of the bow screw at which the sum of the real power levels is a minumum being determined in the regulator (10).

Abstract: A propeller drive for watercraft, preferably for ferry boats and car ferries, which has two propellers located one behind the other in the center-line plane. The forward propeller is preferably located on a marine shaft which exits the hull, and can be driven by means of a drive system. The aft propeller is preferably driven by means of a separate drive system, and the aft propeller is realized so that it can pivot by at least about 90 degrees around an axis, the axis being preferably vertical.

Abstract: A number of embodiments of outboard drive systems that include a combined vertically extending drive shaft driven by the propulsion unit and which drives a generally horizontally extending drive shaft that drives a propulsion device positioned substantially rearwardly of the transom. The propulsion system is supported for steering and trim movement about respective spaced apart axes and these axes are both disposed substantially below the transom of the associated watercraft.

Abstract: A propulsion system for a vehicle having a longitudinal axis comprising a single driving source having a driving shaft; a pair of driven elements, each of the pair of driven elements being spaced from and on opposite sides of the longitudinal axis; a first differential device having an input shaft coupled to the driving shaft and two output shafts; a second differential device having an output shaft coupled to one of the pair of driven elements, a first input shaft coupled to one of the two output shafts of the first differential device and a second input shaft coupled to the driving shaft; a third differential device having an output shaft coupled to the other of the pair of driven elements, a first input shaft coupled to the other of the two output shafts of the first differential device and a second input shaft coupled to the driving shaft; and a control arrangement coupled to the driving source, the first input shaft and the output shaft of the second differential device and the first input shaft and the

Abstract: A jet propulsion unit for a watercraft that employs a pair of counter rotating impellers that are disposed immediately adjacent each other so that the need for straightening vanes is eliminated. The impellers are driven by a bevel gear transmission to rotate in opposite directions, which bevel gear transmission is contained within the jet propulsion unit outer housing but forwardly of the flow path of water therethrough. This bevel gear transmission is driven by a single input shaft through a flexible coupling.