Abstract: A boat provides full operation even in shallow water utilizing an outboard motor. The boat includes a main hull, a displaceable transom to which the motor is mounted and a displaceable hull section. The displaceable transom is received in sliding engagement within two guide brackets mounted to the main hull. The displaceable hull section is connected to the displaceable transom by a hinge along a rear edge. The leading edge of the displaceable hull section is received and rests within a lip in the main hull. Actuator cylinders mounted in alignment with the guide brackets raise and lower the transom and the rear end of the displaceable hull section while the leading edge of the displaceable hull section pivots and slides in the lip. When the motor is raised for shallow water operation the displaceable hull section forms a flow channel for directing water to the propeller and intake port of the motor so as to prevent damage and provide proper and efficient water cooling.

Abstract: A marine craft having a propeller tunnel in which the sidewalls of the tunnel are essentially parallel and vertical and mate with a descending upper surface of the tunnel which optionally can be divided into a transom plate portion, engine plate portion, and bottom plate portion. The bottom plate portion mates with the bottom of the boat hull in a sharp line intersection. A surfacing propeller and associated drive shaft is mounted in the tunnel with a rudder positioned aft of the surfacing propeller. Baffles are provided on the lateral sides of the tunnel and terminate in a forward portion aft of the bottom plate portion of the tunnel. Optionally the exhaust can be vented onto the bottom plate portion of the tunnel to augment the flow of air.

Abstract: A tunnel boat design that is not dependent upon turbulent or resurgent water flow is disclosed. A V-shaped portion of the tunnel and its adjacent rectangular-shaped tunnel portion "direct" water toward a funnel-shaped tunnel portion which "funnels" the water into a semi-circular tunnel portion surrounding the propeller. By obliquely positioning the V-shaped portion, the rectangular-shaped portion and the funnel-shaped portion of the tunnel at pre-determined angles with respect to the keel line of the boat, sufficient water is "lifted" upwardly within the tunnel and directed toward the propeller to propel the boat without causing turbulent or resurgent water flow and/or cavitation.

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 improved shallow draft boat useful for coastal fishing or shrimping operations is provided which substantially reduces drag and thus power requirements, and is so maneuverable that the boat can actually be turned completely within its own length without spinning out. The boat includes an elongated hull having an amidships, funnel-shaped motor well along with an axial trough extending from the well to the boat fan-tail; the trough is preferably of decreasing cross-sectional area along its length so that prop wash created by the motor is forced through a progressively smaller volume, thus producing an uplifting force adjacent the boat's stern. Hence, the boat may pass through very shallow water (as little as about eight inches in depth), at full power inasmuch as the boat actually rides upon the motor prop and flattened stern areas of the hull with very little draft.

Abstract: A full or partial tunnel wedge is positioned in the propeller shaft tunnel ft of the propeller on a waterborne craft. The size and angle of the wedge is determined by the characteristics of the particular craft. The wedge converges water flow and increases water pressure aft of the propeller. The higher water pressure increases the propeller thrust and reduces the hull drag of the propeller shaft tunnel thus reducing the shaft horsepower required to maintain a given speed.

Abstract: A boat hull having a two-stage flow chamber. The first stage flow chamber starts about amidships as a V-shape fairing upward at a shallow angle and flattening out about halfway to the stern. The second stage flow chamber starts at the end of the forward flow chamber curving upward at a greater angle than the first stage and curving downward slightly at the stern. The second stage flow chamber has an inverted V-shape portion connected to the bottom by a pair of narrow sidewalls spreading slightly outward. The forward flwo chamber delivers water to the aft flow chamber free from turbulence. The propeller is disposed in the aft flow chamber and splayed slightly to port. Water exits from the aft flow chamber with minimum turbulence and cavitation.

Abstract: A fan-powered water vessel in which an essentially flat-bottomed main hull portion is provided with a central friction reducing, relatively shallow tunnel whereby air forced into the forward portions thereof serves to form an air film between the major parts of the bottom of the boat and the supporting water surface. In addition, a pair of relatively narrow secondary tunnels are provided on either side of the central tunnel and are of a depth substantially greater than that of the central tunnel so as to confine the friction reducing air film between said secondary tunnels. This construction enables the boat to be utilized both on relatively calm inland waters and swamps as well as in choppy waters. An elevated bow provided at the forward section of the main hull divides and spreads waves to further enhance efficiency. The rear of the hull includes a power supply support housing including an air fan.

Abstract: Essentially one-half of the circumference of the propeller of the marine vessel is arranged in a tunnel having a flow-favorable cross-sectional configuration which follows the flow lines of the water. At the starting region of the tunnel there is arranged a pivotable control plate which can be moved out of a retracted position where it lies in the surface of the tunnel into an extended position removed or remote from the aforesaid retracted position, in order to detach the flow of the water from the surface of the tunnel during rapid vessel travel. The propeller which is driven at a high rotational speed accordingly operates as a partially or semi-immersed propeller. The vessel floor and the control plate are interconnected by an elastically deformable cover plate which is secured to the vessel floor and the control plate in a bending or flexurally resistant fashion.

Abstract: A ski boat for producing a relatively small, well-defined wake and a relatively smooth working table includes a V-shaped keel section. The angle of the "V" increases towards the stern of the hull. A chine panel is mounted at each of the outboard edges of the keel section. A secondary chine is located on each side of the keel section, being parallel to the centerline of the V-shaped keel section and following the contour of the keel section. A concave depression panel is located at the stern of the boat, extending forwardly therefrom into the keel section.

Abstract: A boat includes a transom with an inboard engine disposed closely adjacently forward of the transom, a straight propeller shaft extends rearwardly and downwardly from such engine into a propeller pocket or tunnel extending from a smooth entrance end with respect to the bottom adjacent the transom, the shaft carrying a screw propeller disposed aft of the transom. The propeller pocket terminates rearwardly aft of the propeller and the transom. The tunnel and propeller are completely submerged below the at-rest waterline and the aft extension of the tunnel connects with aft extensions of the bottom to form a bottom extension generally the full width of the boat adjacent the transom. This bottom extension increases the lift of the boat if the tunnel does not interrupt the bottom, and if the tunnel does interrupt the bottom, the bottom extension compensates for the reduction of lift caused by the tunnel portion in the bottom, and a diving platform also extends across such full width above such bottom extension.

Abstract: A marine vessel having a propeller tunnel possessing a flow-favorable cross-sectional configuration following the flow lines of the water. Within the propeller tunnel there is mounted a propeller essentially throughout one-half of its circumference. An adjustable control plate can be extended in order to detach the flow of the water from the surface of the tunnel during rapid travel of the marine vessel. In this case, the propeller functions as a partially immersed propeller at a high rotational speed. There can be provided a control device which adjusts the control plate as a function of the rotational speed range within which the propeller operates. The propeller can be an adjustable propeller conjointly adjustable with the control plate.

Abstract: A clear annular space is provided around the propeller shaft shroud between the aft end of the helical channel proper and the propeller disc. The helical channel is brought far enough around the shaft shroud root so that the aft end of the web formed where the helical channel becomes tangent to the outer hull skin is at an angle not exceeding 40.degree. above the horizontal and preferably not more than 35.degree.. The overall cross-sectional taper of the afterbody takes into account the shaft shrouds as well as the rest of the hull. Because it has been found that the effectiveness of helical channels in smoothing out the torque loads on propeller blades is difficult to predict and sometimes is negative, the method of establishing the configuration by model tests is important. In that method, the radial component of water flow with respect to the propeller disc may be neglected, but both the axial and the peripheral component must be considered in establishing a favorable hull configuration.

Abstract: There is disclosed a water board or surfboard wherein a screw propeller mounted on the underside of the board generates thrust in response to the push-pull action of a hand lever which protrudes from either side of the board. The push-pull action on the lever causes a ratchet-type mechanism to rotate a gear assembly which is connected to the screw propeller shaft.

Abstract: The invention pertains to a propeller pocket for reducing the draft of propeller driven marine craft, and the propeller pocket of the invention utilizes an increasing vertical dimension in the direction of the craft stern, the pocket being defined by planar surfaces, and the water within the pocket being "gathered" as the water approaches the stern to minimize cavitation at the propeller. The pocket is advantageous for use with either inboard, inboard/outboard or outboard driven installations and provides increased drive efficiencies with a reduction in hull draft.