Abstract: A screen system for marine thrusters having at least one constrictor for reducing exit jet cross-sectional area to increase exit jet velocity of a thruster.

Abstract: An assembly for an underwater vehicle that includes a motor, a duct assembly, and an actuator. The duct assembly includes a duct and a propeller mounted within the duct, where the propeller is driven by the motor. The actuator is connected to the duct assembly and the vehicle. The actuator pivots the duct assembly with respect to the vehicle. Alternatively, the assembly includes a motor, a duct having a generally cylindrical shape oriented about a longitudinal axis, and a propeller having an axis of rotation. The propeller is mounted within the duct and is driven by the motor. The propeller and the duct are connected such that the axis of rotation and the longitudinal axis have a fixed orientation with respect to one another. The assembly includes a configuration for changing an orientation of the axis of rotation and the longitudinal axis with respect to the vehicle.

Abstract: A reduced drag marine vessel providing a mechanism that will reduce or even eliminate the drag along the water-solid interface at the hull of the marine vessel. This mechanism is made up of a revolving elastic shell which is similar to a donut shaped belt. This belt forms an interior volume which houses rollers and a framework to support the tubular belt which can be further inflated with a gas to counter the hydraulic pressure of the water outside. Finally, this belt may be housed within a rigid outer tubular shell and contain a propeller within its center so as to form a marine nozzle.

Abstract: An assembly for an underwater vehicle that includes a motor, a duct assembly, and an actuator. The duct assembly includes a duct and a propeller mounted within the duct, where the propeller is driven by the motor. The actuator is connected to the duct assembly and the vehicle. The actuator pivots the duct assembly with respect to the vehicle. Alternatively, the assembly includes a motor, a duct having a generally cylindrical shape oriented about a longitudinal axis, and a propeller having an axis of rotation. The propeller is mounted within the duct and is driven by the motor. The propeller and the duct are connected such that the axis of rotation and the longitudinal axis have a fixed orientation with respect to one another. The assembly includes a configuration for changing an orientation of the axis of rotation and the longitudinal axis with respect to the vehicle.

Abstract: A marine propulsion unit supported from a vessel by a strut contains an electric motor within a housing and a forward propeller driven by the electric motor and having a diameter larger than that of the housing. Hydrodynamic vanes projecting from the surface of the housing counteract tangential flow generated by the forward propeller. An aft section with a pair of counter-rotating blade rows driven by the electric motor is mounted at the rear of the housing and including a shroud surrounding the aft blade rows. The shroud is spaced from the housing so as to receive the boundary layer of liquid passing along the surface of the housing to inhibit cavitation and improve efficiency. Rearward portions of the shroud are movable to form a clamshell causing a reversal of the flow of the liquid passing through the shroud.

Abstract: An ETV-type pump jet having a stator housing with an attachment for minimizing the mismatches between the velocity and direction of the exhaust gas stream flowing out of a stator vane outlet and the velocity and direction of boat and pump jet motion. In one embodiment, a multiplicity of exhaust ducts are attached to the external surface of the stator housing, each exhaust duct being positioned to be in flow communication with the exhaust gas outlet of a respective hollow stator vane. Exhaust gases exiting the exhaust outlets are redirected by the inner surfaces of the ducts to flow in parallel with the rotor shaft axis. In another embodiment, a circumferential exhaust skirt made of sheet metal is substituted for the exhaust ducts. The exhaust skirt surrounds the stator housing and redirects the exhaust gas stream to be substantially parallel with the surrounding water flow.

Abstract: In the embodiments described in the specification, a SWATH vessel has a superstructure supported by strut members from a pair of pontoons and each pontoon has a propulsion module removably attached to the rear end of the pontoon. The propulsion module has a self contained propulsion system including a module body with a longitudinal water passage, a rim drive electric motor, a row of rotatable blades, and an inlet opening at the forward end of he cowl member which is arranged to draw in the boundary layer of water flowing along the pontoon to which the propulsion module is attached. Spaced vanes are provided at the inlet opening to block objects from being drawn into the longitudinal passage.

Abstract: A screen system for marine thrusters is devised having directionally streamlined screens with geometrically-shaped contoured gratings capable of imparting thrust-enhancing effects, thereby permitting high operational efficiency and the ability to operate with little or no reduction in thrust due to cavitation.

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: A deflection snubber assembly for preventing damage to a propeller which is subjected to instances of high force is disclosed. The propeller includes a hub for mounting the propeller on a shaft and a number of blades exteng radially outward from the hub. Outer tips of the number of blades are interconnected by a continuous, circular band. The propeller is constructed to accommodate a predetermined amount of deflection upon instances of high force before being permanently damaged. The deflection snubber assembly includes a housing circumferentially surrounding the propeller, the housing having a number of deflection limiting members, each of the deflection limiting members limiting deflection of the propeller to within the predetermined amount of deflection upon occurrences of the instances of high force.

Abstract: There is described a tugboat (1) having three azimuthal propelling units (10, 20, 30), two (10, 20) of which are juxtaposed below the stern (7), symmetrically relative to the main plane of symmetry (2), while the third azimuthal propelling unit (30) is disposed in the main plane of symmetry (2) the stern (6), preferably before the rearmost towing point (8).

Abstract: A service vessel that is designed for navigating both in the open sea and in ice conditions is provided with a demountable propeller nozzle. For an ice-free navigation period the propeller nozzle is mounted around the propulsion propeller of the vessel, whereas for a navigation period in ice conditions the propeller nozzle is removed. The power absorption of the propulsion propeller is maintained constant during nozzle and nozzle-free operation.

Abstract: The invention features a unique surface configuration which fosters atmosric ventilation and thereby uncomplicatedly reduces drag which is normally associated with implementation of shrouding for a marine impeller. Typical inventive embodiments include a blunt trailing edge and a circumferentially stepped impeller shroud (below the blunt trailing edge), the harmonious union of which affords a generally smooth and unbroken surface which encourages drag-defeating air circulation. During marine navigation, circulation of the air generally describes a path wherein the air first travels linearly downward along the blunt trailing edge, then travels curvingly downward (both clockwise and counterclockwise) along the circumferential step, forming a circumferential air pocket which extends a backward distance increasing in accordance with increasing navigational speed; upon attainment of a threshold navigational speed, the air pocket (virtually) completely surrounds the shroud.

Abstract: A thrust block is positioned by a steerable support in spaced relation to e hull of a seagoing vessel for angular displacement about a propeller axis and the axis of said hull intersecting the propeller axis. Forward and aft sets of propellers are rotatably mounted by hubs in the thrust block for contrarotation by propulsion motors having rotors respectively fixed to the radially outer tips of forward and aft propeller blades and electrically energized by current conducted thereto through stator and rotor windings of transformers respectively mounted in the thrust block and the propeller hubs to avoid propulsive torque transmission by the thrust block. The rotors of the propulsion motors are protectively enclosed by a radially outer shroud assembly which accommodates hydrodynamic cooling during motor operation.

Abstract: A screen system for marine thrusters is devised having directionally streamlined screens with geometrically-shaped contoured gratings capable of imparting thrust-enhancing effects, thereby permitting high operational efficiency and the ability to operate with little or no reduction in thrust due to cavitation.

Abstract: A propeller shroud affixable around the propeller of a water craft. The shroud has a generally cylindrical member which closely surrounds the outer periphery of the blades of the propeller. The front edge of the shroud is deeply concaved to reduce water resistance. Preferably the shroud has several reinforcing blades which are vertically oriented when viewed from the front, but angled rearwardly from the top of the shroud to the bottom. The shroud protects the propeller against damage from rocks, sandbars and the like.

Abstract: A hydrofoil stabilizer for a marine motor includes a hydrofoil wing having a generally planar configuration and a shroud member affixed to an underside of the hydrofoil wing. The shroud member has a generally tubular configuration so as to extend around an exterior of the propeller of the marine motor. The hydrofoil wing is affixed to an underside of the anti-cavitation plate of the marine motor. The hydrofoil wing has a first edge with a notch formed therein so as to receive a portion of the marine motor. A forward edge of the hydrofoil wing has inwardly curved forward edges on opposite sides of the notch. The shroud member is affixed to the hydrofoil wing such that a central axis of the shroud member extends at an angle of between 50.degree. and 20.degree. relative to the plane of the hydrofoil wing.

Abstract: A watercraft drive has a double rudder propeller driven by a driving engine via a driving shaft (1), an angular gear (3, 4) and an output transmission shaft (5). A propeller (6, 7) is arranged at each end of the output shaft. A guiding device made of guide blades (8a, 8b) is arranged between the propellers to correct aerodynamic conditions between both propellers (6, 7) and thus to reduce energy losses.

Abstract: A propeller for fluid propulsion comprises a pair of substantially rigid blades which rotate about their longest dimension in opposite directions, the blades each being oppositely helically twisted along the longest blade dimension and positioned together in synchronously opposite, rotatable condition, with the rotating blades passing by each other in closely spaced relation substantially without physical contact. The blades occupy a tubular housing enclosing the rotating blades in closely-spaced relation between the housing and blades. Further sealing is provided by each blade side carrying a hemicylindrical wall with a concave side facing outwardly, each hemicylindrical wall being helically twisted in a manner identical to the helical twist of the blade. The hemicylindrical walls have a cross-sectional diameter that permits, upon blade rotation, an edge of the other blade to sweep across the concave side of each hemicylindrical wall in closely spaced relation for sealing purposes.

Abstract: A propeller for fluid propulsion (such as air or water) comprises a pair of substantially rigid blades. The blades are mounted for rotation about respective, separate, parallel rotation axes, with the axes being also substantially parallel to the longest dimension of the blades. The blades each define a plate that is oppositely helically twisted along the longest blade dimension compared with the other blade. The blades are positioned together in synchronously opposite, rotatable condition, with the rotating blades passing by each other in closely spaced relation without physical contact. A tubular housing encloses the rotating blades in closely-spaced relation between the housing and blades. Such a blade system can provide a high velocity jet of large mass at relatively low rotational speed.

Abstract: A circular nozzle disposed in front of a propeller of a ship has a leading edge thereof which divided an upper leading edge and a lower leading edge. The upper leading edge approaches progressively the propeller disc toward the lower part thereof, the angle of inclination of the upper leading edge and that of the lower leading edge become different, with the junction part at which the upper and lower leading edges meet being the border, and the junction is positioned in the proximity of a horizontal plane including the axis line of the propeller shaft.

Abstract: A duct fixed to a vehicle propelled through an ambient fluid medium is innally provided with spaced channel passages from which the fluid medium is ejected under pressure tangentially of local duct surfaces through Coanda affected slots at the trailing edge of the duct from which only the ejection of the fluid medium occurs. The supply of the pressurized fluid medium under selective control is limited to different angular segments of the channel passages in order to modify the flow stream through the duct so as to perform certain functions such as thrust control and steerage control effects enhancing vehicle maneuverability.

Abstract: A marine propulsion system comprised of a housing unit having forward and rearward openings, a rotational unit, having forward and rearward openings and having an inner and outer periphery, rotatably secured in the housing unit such that the forward and rearward openings are aligned with the forwards and rearward openings of the housing unit, a plurality of blades rigidly secured to the inner periphery of the rotational unit, and drive means which rotate the rotational unit within the housing unit. Operation of the drive means causes the rotation of the rotational unit and the blades direct water into the forward openings of the housing unit and the rotational unit and out the rearward openings of the housing unit and rotational unit, thereby creating thrust.

Abstract: A propulsion arrangement for a marine vessel having a propulsion unit. The propulsion unit includes a non-rotating housing in the form of a nozzle extending along a principal axis, the nozzle having an inlet opening, an outlet and an internal diameter; a propeller mounted for rotation within the nozzle, the propeller having a plurality of blades radially outwardly delimited by a periphery; a support shaft extending along the principal axis of the nozzle and to which shaft the propeller is affixed; and a support shaft support member in the form of a plurality of arms extending substantially radially from the inner surface of the nozzle to a bearing hub for the support shaft. The plurality of arms are located upstream of the propeller, the arms being shaped so as to impart a pre-rotation on the flow of water upstream of the propeller. The internal diameter of the nozzle gradually decreases from a maximum at the inlet opening to a minimum within the nozzle and then increases towards the outlet.

Abstract: A ship of a displacement type with a pointed bow and a transom stern, a longitudinal length of L, and defining a base plane and a design waterline plane, the ship comprising: approximately sinusoidal waterlines; a surface extending from the transom stern at the design waterline plane to the base plane at about L/2 and defining an angle between: the base plane and an oblique plane, the oblique plane being defined by: a line at the intersection of the transom stern and the design waterline plane and a point located on the surface at about 0.2 L from the transom stern, and a first propeller which is attached to the ship so that the hull wake through the first propeller is less than 0.50.

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

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

Abstract: An air encircled marine thruster cowling includes a cowling that surrounds a propeller and provides an annular blanket of air around the slipstream from the propeller. The cowling includes an inner conical section around the propeller and an outer tubular section around the conical section to form an annular space around the conical section. A duct leads exhaust gas from the engine into the annular space, and an additional duct leads moving ambient air into the annular space, as when a boat is in motion.

Abstract: The present invention relates to a propeller enclosure for enclosing a skeg and propeller. The invention includes a fence portion which defines a first chamber. The first chamber is designed for receiving the skeg of a watercraft motor. The fence portion allows the passage of water therethrough. The invention also includes a solid band portion which defines a second chamber. The second chamber receives the propeller. A first end of the solid band portion is attached to the fence portion. So that the first chamber communicates with the second chamber. The invention also includes a cover which is mounted on a second end of the band portion. The cover allows the passage of water therethrough. The cover includes means for causing trim-tab-like action. The propeller enclosure of the present invention is intended for mounting to a cavitation plate.

Abstract: The present invention entails an outboard power unit comprising an upper drive train compartment, a lower propeller housing, and a pair of laterally spaced connector housings connected between the upper drive train compartment and the propeller housing. An internal propeller assembly is mounted within the lower propeller housing and driven by a flexible drive that is trained around the propeller assembly and extends through the laterally spaced connector housings where the flexible drive is trained around a driven member housed within the upper drive train compartment.

Abstract: A propulsion system for water vessels comprises a rotor located at the rear end of the vessel body, which rotor rotates inside a shroud to generate a propulsion force, and a stator located behind the rotor for recovering the rotation energy created by the rotor. An unexpected high noise reduction is accomplished because the rotor is mounted on a hollow drive shaft, through which an axle extends which is fixed to the body of the vessel, and which axle support the stator and the shroud that surrounds the rotor, without further supporting devices.

Abstract: A housing for the prop of a conventional gasoline or diesel powered marine engine is provided attachable to a bracket mount on the engine. The housing completely encloses the engine's prop and drive shaft and defines a tubular flow path for the water engaged by the prop with the flow path being generally coaxial with respect to the prop's rotation axis. The housing has an anterior inlet port of cross-sectional area A1 and a posterior outlet port of cross-sectional area A2 wherein A1>A2. A smooth transition of the different cross-sectional areas of the tubular housing is effected by an intermediate tapered section. Drive shaft extension means are provided so that the prop rotates in the region of the housing's least cross-sectional area.

Abstract: A protective enclosure and propulsive system for a motor-driven multi-bladed marine propeller includes a shroud housing which is positioned about the propeller that rotates on its axial through bore, the shroud, providing a safety barrier for the propeller and its underwater enviroment, while also improving the thrust of the propeller by having a converging exit cone containing a horizontal control vane between the sides of this cone, where the cone and control vane both extend rearward of the propeller and at the same negative angle relative to the shroud's centerline.

Abstract: A thrust tube is arranged for mounting about the propeller of an associated motorboat unit, as the thrust tube is fixedly secured to the lower housing unit of such a motor unit.

Abstract: The nozzle ring associated with the propeller and rotatable together with it around the vertical axis is designed as a partially open annulus and arranged such that the inner circle of the nozzle--and consequently practically the wing tip circle as well--approximately touches the respective local separating surface between the flow and the floating body or boat.

Abstract: A jet propulsion drive element is disclosed for the increasing of the power yield of jet engines, in particular for watercraft, employing a rotary-driven jet propulsion pipe (11). A thrust propulsion element is disposed at the inner jacket of the jet propulsion pipe (11), covers an outer annular face (A), and is formed as a screw (17). The outer edge of the screw (17) is connected to the inner jacket of the jet propulsion pipe (11). The edge screw (17) is furnished with a through borehole, such that a part of the fluid entering into the jet propulsion pipe (11) is not directly accelerated by the edge screw (17). In addition, drive elements such as a screw propeller (18) can be furnished at the outer jacket of the jet propulsion pipe (11). The invention structure can be employed also for circulating pumps in addition to applications in aircrafts.

Abstract: A propeller system for an outboard motor, comprising a revised propeller, a symmetrical or Kort-type accelerating nozzle, and re-routed exhaust passages, is described. This system permits modification of a standard outboard motor intended for use with a planing type hull to make it applicable to a sailboat immersion type hull. The motor fuel consumption may also be improved.

Abstract: A propeller guard including a cylindrically shaped ring which includes a plurality of evenly spaced openings therethrough. The openings in the ring are formed so as to allow water to pass therethrough during operation so as to improve the performance characteristics, specifically acceleration, plaining, speed and steering, of the motor. The ring is attached to the motor by an attachment bracket which is designed to inhibit fatigue and cyclical loading failure caused by vibrations of the ring during use. The ring is formed in a generally tapered recangular cross section in order to minimize the drag and vibration characteristics thereof during use. The ring is formed so as to be attachable to an outboard motor to surround the propeller thereof to protect the propeller from underwater objects.

Abstract: An ocean-going vessel comprises a stern power plant and side propulsion units attached to the starboard side and to the port side of the ocean-going vessel. Each side propulsion unit comprises two combined propulsion systems having tubular propellers and magnetohydrodynamic drives. The front and rear combined propulsion systems or the starboard side and the port side are united by a tube. Side propulsion units are adapted to provide additional thrust and maneuverability to the ocean-going vessel. Side propulsion units are adapted to provide braking actions by reversing combined propulsion systems.

Abstract: An inherently safer propeller design is disclosed. A conventional propeller has a substantially cylindrical ring affixed to the distal ends of the blades. Preferably, the leading edge of the ring extends beyond the forward most extending portion of the leading edges of the blades. The leading edge of the ring is constructed to absorb the energy of impact with an object. In this manner, damage to the object is substantially reduced. The propeller of the present invention presents a design which, in certain preferred embodiments, substantially eliminates the possibility of severe injury when a moving propeller collides with a human or animal. Preferably, the energy absorbing leading edge is comprised of a hollow sheet metal section, which may be foam-filled. Alternatively, the leading edge may be comprised of an elastomer or other material which absorbs energy. Several ways of attaching the leading edge to the ring to create a detachable and replaceable structure are disclosed.

Abstract: A water jet propulsion module is generated about a central axis and has an inlet opening and a discharge opening concentric with said axis. The module includes a stator having an inner wall and an outer wall with curved stator vanes connected between said inner and outer walls. An impeller shroud is adjustably connected to the outer stator wall. A motor secured to the stator drives a planetary gear drive attached to an impeller by a parabolic impeller cone. The impeller draws water into the inlet opening and drives the water past the stator vanes out of the discharge opening along a substantially linear path at high speed and pressure.

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

Abstract: A motor-boat hull (10) includes a planing bottom (C) having a V-shaped forward portion, two float-like side portions (14) connected forwardly to the V-shaped portion (12), and a flat recessed aft portion (16) delimited by the side portions (14) and forwardly by a transverse step (18) connecting it with the V-shaped forward portion (12) of the bottom (C).

Abstract: A device for protecting a propeller of a boat motor and for improving the efficiency and therefore the performance characteristics of the motor. The device includes a tubular shroud main body portion which includes a pair of half-sections pivotally secured to one another about a first pair of lower, axially aligned edges. Fastening devices are provided along a second pair of upper, axially aligned edges for clamping the half-sections about the propeller. Mounting plate assemblies are mounted on the main body portion half-sections adjacent the upper, axially aligned edges for resiliently gripping a pair of anti-cavitation plates projecting horizontally outwardly from the motor housing. The shroud main body portion is also provided with an elongated slot along the first pair of axially aligned edges for receiving a skeg projecting downwardly from the housing below the propeller. Forward and rearward grills are provided to prevent inflow of trash or other debris into the shroud.

Abstract: A ship's propulsion duct surrounding a propeller is constructed with a main body of glass-reinforced synthetic plastics material, and at least the throat of the duct is protected from the erosive mechanical effects of flow breakdown at the tips of the propeller blades by force-absorbing resilient material. The resilient material may be an inset ring of elastomer, or a lining of elastomer secured over the whole inner surface of the duct, or a resilient coating applied to the duct surface by painting.

Abstract: A screw propeller (10) for boats includes two counter-rotating screws (12, 16) coaxial with an annular nozzle (20). The aft screw (16) has a smaller diameter than the forward screw (12) and the nozzle (20) has an annular duct (B) situated upstream of the rear screw (16) and arranged to discharge the exhaust gases from the engine.

Abstract: A propeller enclosed in an open tube and attached to the tube, with the tube being driven by an engine through a ring gear rack on the outside of the tube, a stationary housing concentrically outside the tube and attached to the boat hull, bearings and seals between the housing and the tube to permit the space between the housing and tube to be filled with lubricating oil, and a pivotable rudder located partially inside and partially outisde the aft end of the tube.

Abstract: This arrangement concerns a flow guide surface for ship propellers, at least for twin propellers, the propellers being mounted by means of propeller brackets. It is provided for to arrange, at least in the region between the arms of the propeller brackets, a sectioned arcuate guide surface. This guide surface possesses a mean camber line converging backwardly towards the propeller shaft and the outlet edge has a distance to the propeller shaft amounting to between 70 and 130% of the propeller radius. This arcuate section of the guide surface is connected, on the side facing the ship's hull, to an approximately horizontal radial part.

Abstract: A flow guide is employed with a marine propeller having blades, and:(a) the guide is substantially cylindrical and has fore and aft opposite ends,(b) the propeller has an axis of rotation, and said flow guide has an axis, said axes being substantially coincident,(c) the flow guide having a rim defining a bore diameter at said aft end which is substantially the same as the propeller blade tip diameter, and(d) the blades having tips and the propeller having a location characterized in that the blade tips rotate adjacent said rim at the aft end of the flow guide. Typically, the guide is mounted to the hull so that the guide axis extends downwardly and rearwardly, at an angle to horizontal.