Small Vessel Capable Of High Tow Force

Abstract

A small watercraft with watertight hull and an area at the rear in close proximity to the waterline that provides a means to mount payloads. Engines powering propellers are installed forward of the payload area and are covered by a water-tight deck with openings for intake air. Ancillary systems to support the engines and electrical components are provided in a conventional manner. A feature of the present invention is that the hull has been modified to permit a tow cable to pass through the hull from a towing winch to a towed body. The present invention moves the reaction from the tow force forward of the craft transom and low in the hull which greatly improves the stability of the small vessel particularly when it is operating in rough water. The present invention is applicable to any size of the hull and any materials that the hull is fabricated from.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]Not ApplicableSTATEMENT REGARDING FEDERALLY SPONSORED RESEARCH[0002]Not ApplicableREFERENCE TO SEQUENCE LISTING[0003]Not ApplicableBACKGROUND OF THE INVENTION[0004]This invention relates generally to a watercraft which is used for towing objects at or below the surface of the water. The power to propel the craft through the water is the total of the resistance of pushing the hull through the water plus the tow force. The tow force exerted by conventional watercraft is small compared to the force required to push the hull through the water.[0005]When the tow force is large compared to the force required to push the watercraft through the water, the location where the tow force is applied to the craft can cause the vessel to become unstable. Specific provisions are made to maintain the stability of the vessel. For example, commercial tugboats attach the tow cable as close to the center of gravity of the vessel as possible. The center of gra...

AI Technical Summary

Benefits of technology

[0009]The hull is shaped to develop minimal resistance when moving through the water. There is a vertical slot formed through the hull at the transom along the centerline of the craft extending from the top of the aft deck area to the hull plating. The slot is positioned so that a tow cable can pass through the slot when the angle of the tow cable is below horizontal. Conventional winches and reels are utilized to deploy and recover the tow cable. Wear resistant material is attached to the lower and aft edges of the slot thru the hull to eliminate chafing between the cable and the watertight hull boundary.

[0011]When a cross current is added to the operating conditions above, the watercraft will need to operate at a angle, referred to as yaw angle, to the desired direction of motion to counteract the force of the current. The tow cable will still extend through the slot in the hull and exert both a longitudinal and a vertical force on the craft. However, due the yaw angle of the craft, the tow cable will be in contact with the lower edge of the slot through the hull which will exert a transverse force on the hull. The distance from the vertical center of gravity will be greatly reduced compared to the prior art where the tow cable goes over the side of the upper deck. The result is a significant reduction in the destabilizing moment imposed by the tow cable on the craft.

[0012]The slot through the hull is constructed in such a manner so that the stresses created in the craft structure due to the applied forces, by the water on the hull, by the tow cable, or by forces on the craft from hoisting, do not exceed the yield strength of the material used to construct that area of the craft. The inside surfaces of the edges of the slot through the hull are covered to prevent the tow cable from chaffing on the edge and to increase the bend radius of the tow cable as it passes the edge.

[0013]It is an object of this invention to provide a stable watercraft that has a high tow force compared to the force required to push the craft thorough the water.

Problems solved by technology

When the tow force is large compared to the force required to push the watercraft through the water, the location where the tow force is applied to the craft can cause the vessel to become unstable.

The limitation of conventional small watercraft for towing high forces is increased as the roughness of the water surface increases.

This is because when the additional tow force is combined with the destabilizing forces of the waves, the craft becomes unstable and increases the potential to capsize.

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