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

Abstract: The invention is a boundary flow control system and method which comprises heating elements 24 to trigger boundary layer transition and audio speakers 83 to provide acoustic suppression 51 of boundary layer turbulence 52. The trigger and suppression control are activated by a feedback amplifier 82 which reads boundary layer flow conditions using an anemometer probe 81. The active control of the boundary layer permits delay of flow separation and a reduction in skin friction drag as compared to natural flow conditions.

Abstract: A finger skirt for an air-cushion vehicle wherein the bottom edge of each finger skirt, when it is in the state of inflation by the pressurized air for the levitation of the hull, is shaped so that it extends horizontally at the location where it comes in contact with the pressure-receiving surface, the bottom edge being formed so that its cross section is a circular arc.

Abstract: Hydrofoil craft, particularly a method of economically modifying a conventional hull by means of foils to obtain enhanced lift and rough water stability. The method is characterized by defining an axial tunnel(s) intermediate the bow and transom of a catamaran hull or V-bottom hull modified with chine mounted aerofoils; positioning a flexible dihedral foil beneath the water line and on either side of the bow so as to obstruct and create a turbulence in the forward end of the tunnel, while cushioning shock and lifting the bow; and simultaneously enclosing the transom end of the tunnel with a foil, so as to compress the turbulence and lift the transom.

Abstract: An improved performance and high stability marine surface vessel that is supported at least in part by a pressurized gas cushion where the pressurized gas is supplied to the gas cushion normally by mechanical apparatus such as a powered blower. The pressurized gas cushion is restrained, at least partially, by a recess built into the underside of the hull with significant advancements including a forwardly extending bow member that helps lift the bow over rough seas, water impact relief openings in the side hulls, movable and optionally remotely controllable stern seal member sections that allow control of recess gas cushion depth, pressure and other gas cushion characteristics, and a control system for a movable stern seal member. The advancements also include a forward movable seal attached structure that greatly increases movable seal life. The above advancements may be used singularly or in various combinations.

Abstract: A hull for a sail boat, wherein devices for the continuous hydrodynamic conversion of a displacement-type hull into a planing-type hull, even during sailing are provided on the stern in front of the hull end.

Abstract: A water vehicle includes a longitudinally elongated hull having a first portion adapted to separate the water by movement of the hull through the water. Foam is generated by the separation of the water. A second portion of the hull is adapted to contain the foam underneath the hull. The vehicle will be supported during propulsion at least in part by a surface of the foam.

Abstract: A surface effect transport vehicle is provided having a structure supported by a cushion of pressurized air generated from a blower. The propulsive source of the vehicle is independent from the power source of the blower. The propulsion source includes at least one retractable propeller device adapted to be made operative during travel over the water and nonoperative during travel over land, and at least one retractable wheel device, for travelling over land or in shallow water, which is made operative when the propeller device is retracted to its nonoperaitve condition, and vice-versa. Preferably the wheel device has at least two lateral faired propellers operative when the propeller device for propulsion over water is retracted to its nonoperative position. The supported structure includes automatic controls that simultaneously controlling the lift properly speaking, the attitude of the vehicle as well as its stability when passing over an obstacle or at the time of a dynamic disturbance.

Abstract: A surface effect ship and a system of cushion pressurization by forcing into the cushion chamber a homogeneous mixture of air and gas. The surface effect ship is provided with a hull, having propulsion device, associated with rudders, and a skirt to confine the pressurized cushion chamber beneath the ship. In order to decrease the empty weight and thus to increase the performance of the surface effect ship, the traditional heavy and complicated mechanical lift system for cushion pressurization is substituted by a combination of a source of gas with a gasdynamical converter, as a lift system, to feed the cushion chamber of the surface effect ship by a homogeneous air and gas mixture. A turbojet engine is used as a source of highly energetic gases, and the gasdynamical converter is used for augmentation and homogenization of the mixture of air and gas.

Abstract: There is disclosed an improved stern seal construction for air cushion surted operating type marine vessels which consists of an array of inflatable, vertically oriented inverted truncated open-ended cones or fingers. These fingers are individually attached to and mounted to depend in side-by-side relation from the bottom of an inflatable bag which in turn is mounted upon and extends transversely across and below the bottom of the stern end of the vessel's hull. The fingers are arranged in side-by-side pressed together relationship, and thus assume in horizontal section generally rectangular forms. In side view sectional profile the finger and bag contours are so balanced that a minimum load at the bottom ends of the fingers will permit them to raise to allow for passages over rough objects. The front or leading panels of the fingers are stiffened somewhat toward their bottom ends, and are extended under the open bottoms of the fingers beyond their trailing panel portions.

Abstract: Disclosed is a hovercraft having a pair of air cushions, associated with each air cushion is a rotatable fan which partly produces lifting force and partly propels and maneuvers the craft. The fans are mounted perpendicular to the direction of travel, peripherally on the craft, wherewith the forces produced have long moment arms, and consequently produce a strong turning torque. The fans are mounted on the craft in such a manner that their orientation may be adjusted both horizontally and vertically with respect thereto.

Abstract: A pneumatic plunger system for use in a commercial seine fishing vessel, comprising apparatus for expelling a mixture of forced air and water through a plurality of nozzles that are located along the keel of the vessel. The forced air and water which is ejected through the nozzles creates a wall of air bubbles extending substantially vertically and downward from the keel. Fish swimming between the net and the wall of air bubbles are startled by the air bubbles and are repelled into the net.

Abstract: A catamaran-type air cushion craft has two floats (211) arranged spaced apart parallel to one another which are connected together at the top by a connecting structure which carries built-in structures and which is sealed at the bottom by an air-tight transverse deck (216). The connecting structure includes at least two double transverse trussed girders (217) arranged spaced apart behind one another, which at least partially contain transverse hollow cavities (212) for passageways and line accomodating hollow cavities (213, 213'), with containers (214) and longitudinal passage and supply elements (215) being mounted at the front and/or rear sides of the double transverse trussed girders.

Abstract: An improved performance marine surface vessel with a recess in its underside that is pressurized with gas to form a supporting gas cushion that carries a substantial portion of vessel weight. The gas cushion is restrained by catamaran-like sidehulls, a movable seal forward, and substantially rigid aft seal. The recess is shaped on its upper surface to provide good ride qualities in rough seas and maximum stability in roll. In some instances a center hull and/or a skeg-like device are utilized to separate portions of the recess. The sidehulls can include secondary lifting surfaces on both sides to aid in operation with the pressurized gas supply not operating. The forward movable seal is best made in several elements that are individually removable through an opening in the front deck. The seal elements are formed at their top portion by a substantially rigid cap that also attaches the seal to the hull.

Abstract: A rapid boat docking and efficient loading/unloading apparatus is provided that utilizes an attachment system. The attachment system also serves as a gangplank in the preferred embodiment to attach the boat to the dock. The principal forces required to attach the boat to the dock are optionally part of the boat itself in the form of an air lifting system that holds the boat at a level higher than its waterline at rest so long as an air blower is in operation that supplies pressurized air to a chamber or recess on the underside of the boat. As blower power is reduced, the boat settles into its docking slip with the attachment system. The attachment system is located preferably at the bow on each side of the boat, and comes into contact with the dock as the boat lowers. In the preferred embodiment, attachment arms which are part of the boat have a half cylindrical track on their underside which fit into a mating socket track on the dock.

Abstract: A surface effect vessel of a type comprising a buoyed structure with two side keels (20), a rear seal apparatus (100) and a forward seal apparatus cooperating to delimit a central buoyancy cushion (300). The rear seal contains a horizontal extension enclosure (100). A first piping system (54) connects a pressurized air generator (50) to the enclosure (100), and a second piping system (58) connects the central cushion (300) and the pressurized air generator (50). Fluid communication holes (150) are provided between the enclosure (100) and central cushion (300). The piping system (54, 58) and the fluid communication holes (150) are defined to ensure inflation of enclosure (100) to a pressure higher than the pressure of the central cushion (300).

Abstract: The present invention relates to a surface effect ship including a catamaran type supported structure with two side hulls connected by a central box structure, able to operate either as a buoyant displacement vehicle or as an air cushion supported vehicle. The ship includes, within the hulls, continuous longitudinal stiffeners mainly to bear longitudinal bending stresses within the central box structure connecting the two side hulls and built-in within these hulls, transverse beams mainly to bear transverse bending stresses, and at least two reinforced transverse bulkheads located in the bow and the stern of the ship respectively to bear transverse bending stresses applied on the bow and the stern of the ship, resulting from twist moments applied diagonally to the ship. Each bulkhead includes a transverse beam within the box structure with a vertical web and extending down within the hulls and strengthened within the box by upper and lower horizontal flanges.

Abstract: A novel exhaust system for both conducting engine exhaust gases away from and aft of the personnel occupied portion of a marine vessel and protecting the sides of the hull of the vessel from damages thereto during docking or other "working" maneuvers of the vessel is provided.

Abstract: A ground effect vehicle consists of a central, wing-like support body (1), floats (5) and/or undercarriage units located on both sides of the support body, a thrust generator (11) located in front of the support body, a control surface (14, 16) and a cabin (17), located on top of the support body for at least one person and, if required, for payloads. In order to increase the ground effect and to realize the ground effect even at low speeds, a nose (6) extending far forwards is provided in front of the support body (1), which nose forms an airflow duct (7) directed under the support body, the thrust generator (11) being located under the front region of the nose (6) in or immediately in front of the airflow duct (7).

Abstract: The present invention concerns hull shapes for a surface effect ship, including a catamaran type supported structure with two side walls (100) connected by a center platform (200), able to operate either as a buoyant displacement vehicle, or as an air cushion supported vehicle, the side walls (100) confining, with two sealing devices (310, 320), the supporting center air cushion (c).

Abstract: In a multiple-hulled marine craft an opening (313) which can be closed in air-tight and water-tight manner by pivotable flaps (314) is located in the transverse deck (312) beneath the connection structure between the two floats (311) (FIG. 2).

Abstract: A self-propelled waterborne vessel has a generally flat hull undersurface aft of the bow region from which extend side walls (10) and keels (11, 12) defining longitudinally extending channels (8, 9) of which the length approximates to one-third of the length of the vessel. Ducted portions of the channels contain propellers (21) aft of which the ducted portion cross-section is selectively variable by transversely pivoted vanes (18). The attitude of the vessel is controllable by the vanes (18) and by further vanes (36) at the stern. Steering is effected by a propulsive steering unit (25) comprising ducts containing propellers (32) and transversely pivoted vanes (34). Additional ducted propellers (46) can be provided aft and may be retractable into the hull.

Abstract: An air-cushion vehicle of the type having a flat rigid platform with rigid longitudinal walls attached to the platform. In such an air-cushion vehicle a plurality of transverse trough-shaped skirts are provided so as to form a space bounded by the skirt and the platform which, when supplied with higher pressure air, serves to provide an air cushion chamber. The vertical height of the air cushion chamber can be varied in accordance with the present invention by extending or retracting the material of the trough-shaped skirts by way of an adjustment mechanism. In a preferred embodiment, the adjustment mechanism comprises a skirt bar attached to each of two longitudinal edges of the skirt and a mechanism for moving the skirt bars sideways closer together or further apart, thus varying the skirt's vertical dimension.

Abstract: A catamaran air cushion water vehicle has two spaced apart floats (111) which extend parallel to one another in the direction of travel, wherein the cross-sections of the floats become broader from the bottom to the top and wherein the floats are rigidly connected together at the top by a deck structure (113). Furthermore, resilient skirts (123, 124) are arranged up to the stem and at the stern between the floats (111), extend at least approximately down to the water surface, and, together with the floats (111), bound an air space (125) between the base of the deck structure and water surface. In accordance with the present teaching the floats (111) each have a hull section (112) which broadens out in step-like manner essentially above their float region (115) which is submerged during travel in the displacement mode. The hull sections (112) serve to accommodate machinery, such as the propulsion units, and the deck structure (113) is attached to the upper end regions of the hull sections (112).

Abstract: An improved seal is provided for an air cushion vehicle which has side hu and a wet deck therebetween. The improved seal includes a flexible sheet like device which is connected to the wet deck and which extends between the side hulls so as to present a forward surface. A plurality of elongated flexible panels are connected to the air cushion vehicle and extend downwardly across the forward surface of the flexible sheet like device, and elongated panels laterally overlap one another so as to provide a continuous field barrier across the vehicle. With this arrangement the panels cooperatively flex and slide with respect to one another to discretely respond to wave actions, thereby minimizing drag and wear capabilities of the seal.

Abstract: A vessel with a ballast system including a plurality of ballast tanks provided with means for feeding water into the tanks and expelling water therefrom and an air bubbling system including underwater openings and means for blowing air through said openings into the water surrounding said vessel. The ballast system and the air bubbling system include a common tube system being alternatively connectable to the ballast tanks, for operating the filling and emptying of the tanks, and to the air bubbling system for conducting air to the underwater openings as described in U.S. Pat. No. 3,580,204.

Abstract: This invention concerns a surface effect vessel whose type comprises a buoyed up structure fitted with two side keels (20), an rear seal apparatus rear and a forward seal apparatus (200) both delimiting a central buoyancy cushion (300). According to the invention the forward seal apparatus (200) consists of an upper horizontal extension shell (210) extending between the two side keels (20) which communicates with the central cushion (300) so as to be supplied by it and two rows of lower multilobe skirts (230, 250) connected below the upper shell (210), which converge towards the center of the central cushion (300) from top to bottom, and whose concavity faces the center of the central cushion (300), the multilobe skirts (230, 250) together delimiting the intermediate chambers (254) which communicate with the upper shell (210) via ports provided in its wall.

Abstract: The disclosure concerns a vehicle which is both lifted and propelled by air flow. The vehicle comprises an upper deck, a depending peripheral side wall and a flexible, perforated sheet secured beneath the bottom of the side wall, thereby defining an open plenum. A propeller in an air flow directing cowl seats atop the deck and part of the air flow is directed into the plenum and the remainder of the air flow is directed to move the vehicle. The underside of the upper deck disperses air in the plenum. Alternatively, the propeller is part of a duct which directs air into and disperses it around the plenum. The cowl includes an air dam for trapping reverse flowing air. A rudder directs the motion of the vehicle. The plenum narrows in width toward the front and diminishes in height away from the plenum inlet through the upper deck.

Abstract: An improved bow and/or stern seal is provided for a surface effect vehicle herein the vehicle has a pair of spaced apart side hulls which are joined by a wet deck, and the bow and stern seals extend between the side hulls so that an air cushion can be formed between the side walls and the bow and stern seals. The improved seal includes a portion of the deck having an opening for providing an air inlet to the air cushion. An elongated pneumatic bag is mounted along its length to the bottom of the wet deck, is sealed at its ends and is positioned to receive air from the deck opening along its forward side. Provision is made for a passageway between the side hulls for directing air around the forward side of the bag.

Abstract: A self-propelled air cushion vehicle includes a traction wheel device comprising at least two separate traction wheel units. Each traction wheel unit includes at least two consecutive wheels surrounded by a common caterpillar track, preferably two such wheel pairs arranged side by side. The traction wheel units are arranged in the longitudinal direction of the vehicle, one at the fore end of the vehicle and the other at the rear end of the vehicle, both at the central longitudinal axis of the vehicle.

Abstract: An improved performance marine surface vessel with one or more recesses that intersect the hull substantially beneath the waterline thereof, the recess bounded by stabilizing, planing, catamaran-like sidehulls with bow shaped members located at its forward and aft portions and optionally therebetween, with the recess being supplied with pressurized gas to maintain a lift-augmenting, restrained pressurized gas layer under the hull that improves load-carrying capability, efficiency and ride quality. The keels of the sidehulls diverge for at least a portion of their length. The fore and aft bow shaped members, and optional intermediate bow sections in some cases, contact the water like small bow sections thereby improving hull ride and handling characteristics and reducing gas leakage.

Abstract: A tunnel-type boat-hull construction is operative with substantially reduced frictional resistance in the water and also with improved high-speed stability. An air-withdrawal port is provided in the bow portion of the tunnel, and exit ports which are interconnected to the withdrawal port are provided along generally downwardly facing submerged surfaces of the hull. When the boat hull is operated in a forward direction, air is captured in the forward portion of the tunnel, and a portion of the air is withdrawn through the withdrawal port and is exited through the exit ports. The air which is exited through the exit ports provides lubrication for the submerged hull surfaces so that the hull is operative with substantially improved efficiency; and because the air is withdrawn from the bow portion of the tunnel, the bow uplift effects which are characteristic of conventional tunnel-hull-type vessels when they have been operated under high-speed conditions are substantially reduced.

Abstract: A vessel with a ballast system including a plurality of ballast tanks provided with pumps for feeding water into the tanks and expelling water therefrom and an air bubbling system including underwater openings and compressors for blowing air through said openings into the water surrounding said vessel. The ballast system and the air bubbling system include a common tube system being alternatively connectable to the ballast tanks, for operating the filling and emptying of the tanks, and to the air bubbling system for conducting air to the underwater openings as described in U.S. Pat. No. 3,580,204.

Abstract: There is disclosed an improved air cushion seal system of the inflatable lobe type such as for operating between the sidehulls of a surface effect ship (SES), wherein in accordance with the invention at least the lowermost lobe of the system is partially closed at each of its opposite ends by a fabric sheet which is inset from the ship sidehulls. These substantially impervious to air passage sheets are affixed to the side edges of the lower loop of the lobe and up and around its aft end, and optionally to the upper loop of the lobe, to minimize scooping and water filling of the lobe, and to operationally stabilize the lobe.

Abstract: An ice lubrication system for easing the passage of a ship through ice laden waters. A pressurized flow of water passes through a nozzle into the inlet of a mixing chamber comprising a venturi where gas from a gas manifold is mixed with the water. The effect of the venturi is to first cause the gas to mix into the water flow and, after passage of the flow through the venturi, to cause the gas to emerge from the water. A frothy combination of gas bubbles and water is thus created which is discharged through openings in the ship's hull below the waterline. Once discharged, the gas and water combination rises up the side of the hull to provide separation and lubrication between the hull and floating ice.

Abstract: A boat hull having at least one extending hull (10), an intermediate hull portion (13), a flexible plenum chamber (14) to raise and lower the intermediate hull portion (13), and a flexible skirt (17) formed integrally with the intermediate hull (13) to entrain air beneath it so that its lower extremities are clear of the ground or water.

Abstract: A fluid flow control system for connecting a source of pressurized fluid with a region of varying pressure, comprises a fluid supply duct having an inlet end connectable to the pressure source end and an outlet end connectable to the region of varying pressure, a vent duct disposed between the inlet and outlet ends, and a vent valve sensitive to change in pressure within the supply duct and operable so as to control the escape of fluid from the supply duct. The vent valve preferably comprises a flexible wall member of hollow, inflatable form. In operation of the system, a relatively small amount of fluid is allowed to escape when pressure at or adjacent the outlet end of the supply duct is substantially less than that at or adjacent the inlet end thereof, and a relatively large amount of fluid is allowed to escape when the pressure differential is reversed. The system is particularly useful as a "ride" control for gas-cushion vehicles operating over rough ground or water.

Abstract: A hull or flotation arrangement for an apparatus moving through water is provided with steps forming a plurality of surfaces on which the apparatus rides. The steps are arranged such that the lower edges of a predetermined number of the steps extend deeper into the water than a predetermined number of the lower edges of the remaining steps. The lower points of the steps are arranged so that predetermined numbers of them are deeper than predetermined numbers of others, so that there is a progression extending deeper and deeper into the water. The steps are so constructed that as the apparatus is moved forward, it rises upwardly in the water, causing the steps to rise out of the water progressively as the speed increases, with the hull then riding on only a few steps, thus reducing drag and increasing efficiency.

Abstract: A water jet propelled boat that includes a source of pressurized air that by a single action control may be delivered to bow and stern portion positioned resilient bags to inflate the same to vary the contour of the wetted portion of the boat to a desired configuration. The boat includes a number of laterally spaced sponsons that have forward bottom surfaces that taper downwardly to merge into substantially straight rearward bottom surfaces on which the boat rides when traveling at high speed. Pressurized air is discharged from the source to flow rearwardly under the boat and impart a lift to the latter. The desired configuration of the bags is one which in combination with the action of the sponsons and the rearwardly flowing bubbles results in the boat moving through the water in a fuel efficient manner.

Abstract: An ice lubrication system for easing the passage of a ship through ice laden waters. A pressurized flow of water passes through a nozzle into the inlet of a mixing chamber comprising a venturi where gas from a gas manifold is mixed with the water. The effect of the venturi is to first cause the gas to mix into the water flow and, after passage of the flow through the venturi, to cause the gas to emerge from the water. A frothy combination of gas bubbles and water is thus created which is discharged through openings in the ship's hull below the waterline. Once discharged, the gas and water combination rises up the side of the hull to provide separation and lubrication betwen the hull and floating ice.

Abstract: A drag reducing device for barges including a flexible mat carrying a plurality of transversely spaced, elongated flexible tubular air passages open at the top and bottom, suspended from one end of a barge, extending transversely of the barge and adapted to swing longitudinally of the barge as the barge moves longitudinally through a body of water, whereby air from the atmosphere is conducted through the tubular air passages to an area beneath the barge.The drag reducing device is particularly adapted for suspension between the adjacent ends of a pair of barges connected in tandem so that the flexible mat and tubular members swing in a trailing longitudinal direction to direct air beneath the bottom surface of the trailing barge.

Abstract: A bottom exhaust type high speed boat has a hull including a grooved bottom. The engine exhaust pipe extends into a midportion of the grooved bottom. A duct fixed to the surface of the hull extends between the opening of the exhaust pipe and the front of the grooved bottom for transporting exhaust gases to the front of the grooved bottom. The grooved bottom is separated into a forward part and a rearward part, having different depths, by a stepped surface. The exhaust opening is on the rearward part whereas the duct is on the forward part. Gas leakage prevention grooves surround the grooved bottom. A triangular projection having dovetail sides extends from the grooved bottom and the engine propeller is positioned on the projection.

Abstract: There is disclosed an improved air cushion supported vehicle of the relatively high speed operating "surface effect ship" type, having a main hull and a pair of rigidly constructed opposite side walls or hulls depending therefrom, and bow and stern air cushion sealing means. Each of the side hulls terminates at its lower extremity into an outwardly side-wise canted water planing bottom surface or keel into which one or more non-coplanar surface discontinuities is/are provided for locally accommodating in slightly recessed relation therein the ship propulsion propellers. The configurations of said discontinuities are such as to reduce the requisite angles of the propeller driving shafts relative to the ship hull; thereby reducing the ship draft (propeller clearance) requirements, while also providing under high speed operating conditions improved propeller operating efficiencies and substantial maintenance of the desired air cushion sealing efficiencies of the side hull keels of the ship.

Abstract: There is disclosed a surface effect ship stern seal system comprising a plurality of side-by-side vertically standing inflatable fingers of open top form, the leading end portions of the fingers being attached to the hull by resilient means and the bottom edges of the sidewalls of the fingers being closed by water planing plate means. The upper edges of the sidewall portions of the fingers are carried by tension ropes connecting at their leading ends to said resilient means and at their aft ends to the ship hull, reclining therebetween in catenary fashion.

Abstract: There is disclosed in a multiple lobe air cushion seal system an auxiliary air inflated bounce damping lobe interfacing the cleft between the lower ends of the two lowermost lobes of the system.

Abstract: A canopy system for deployment around the periphery of a vessel floating on a body of water is disclosed primarily for use in connection with drillships in Arctic waters.

Abstract: A marine vehicle, which may comprise a sidewall gas-cushion vehicle, is provided with a pair of steering rudders, a sensor for detecting incipient undesirable motions of the vehicle, and an electrical, mechanical, and/or hydraulic system, or a hybrid thereof, for operating the rudders so as to apply restoring forces to the vehicle. The steering rudders are mounted beneath the vehicle and on opposite sides of the longitudinal axis thereof, being disposed in planes which are inclined to the vertical and which intersect above the rudders. The sensor for detecting incipient undesirable motions of the vehicle may comprise an angular rate and/or an accelerometer. The signal output of the sensor is applied to a band pass filter of pre-determined transfer function and the filtered sensing signal is applied to a summing point, to which is also applied a steering command signal.

Abstract: A seal structure for an air cushion vessel includes an inflatable bag secured to the hull and a transversely stiffened lobe portion maintained therebeneath. The stiffened lobe portion consists of a membrane with an array of spaced, transverse stiffener members connected thereto. The colinear stiffener members are interconnected in end-to-end relationship. According to one embodiment, the end portions of the stiffener members are connected to support stays which are connected either to the bag structure or to the forward portion of the hull. The support stays may comprise cable elements or membranes which form continuations of the stiffened lobe membrane. Additional support for the stiffened lobe portion is provided in the form of a plurality of rear support elements which set the orientation and configuration of the stiffened lobe portion and limit the downward deflection of the stiffened lobe portion.

Abstract: An apparatus is provided for effecting rapid changes in the geometry of a flexible wall structure forming at least a part of the cushion seal on an air cushion vehicle. The apparatus comprises one or more inflatable members co-operating with the flexible wall structure and an air ejector for rapidly introducing pressurized air into each inflatable member. Each inflatable member may be constituted by a wall structure portion of hollow construction. The invention finds particular application in assisting directional control of an air cushion vehicle.

Abstract: For enhancing the maneuverability, speed, survivalbility, and targeting accuracy of a torpedo moving below the surface of a body of water, ultrasonic vibrations are set-up at the exterior of the torpedo hull, using controlled piezoelectric crystals to generate the vibrations in the 5-50 KHZ and 5-30 KW frequency and power ranges. Ways are disclosed for operating the piezoelectric crystals to steer the hull without need for mechanically moving parts such as flaps or fins.