Patent Publication Number: US-2007113772-A1

Title: Shallow Draft Boat

Description:
This application claims the benefit of U.S. Provisional application Ser. No. 60/597,250 filed Nov. 18, 2005. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates generally to recreational boats and, more particularly, to a shallow draft boat which permits access to extremely shallow in-shore areas.  
     BACKGROUND OF THE INVENTION  
      Fishing as a recreational sport is popular throughout the world. Sport fishermen often fish from boats near the shore or in other shallow areas which attract fish. Boats used in fishing in shallow areas must have a variety of characteristics.  
      As described in U.S. Pat. No. 6,406,341 to Morejohn, a shallow draft boat must get fishermen to the place they wish to fish quickly and comfortably. Transit to choice fishing areas sometimes includes long passages over open water in which waves may be encountered. Stability and speed thus become important. In a small boat (about 16-22 feet in overall length), speed is obtained by causing the boat to ride on top of the water in what is often referred to as “planing” rather than in the water in the displacement mode. Adequate power and a proper hull shape are necessary for planing. Once at the location of fishing, shallow draft characteristics become more important. Reefs, sandbars, shallow flats, and various obstructions are common near the shore in smaller lakes and rivers. A boat with a shallow draft may ride over a particular obstruction when a boat with a deeper draft will hit it and possibly suffer damage.  
      With fishing boats, a shallow draft is important in two different modes of operation. When the outboard motor is in a down position providing power to the boat, the outboard motor is often the lowest portion of the boat. Thus, the shallow draft with the outboard motor down is important to protect the motor from damage. When one is fishing, one often shuts the motor off and tilts the outboard motor into the up position. In this position, the outboard motor is entirely out of the water and the draft of the boat is now determined by the most downwardly extending portion on the boat hull. This is important to fishermen as the boat may drift or is sometimes polled to move it quietly through shallow areas. A shallow draft boat can quietly pass over obstructions which would stop a deeper draft boat.  
      Obtaining good performance characteristics and good shallow draft characteristics both with the motor down and motor up is difficult. Design elements which help in one performance or draft area often appear to hurt in another performance or draft area. Thus, conventionally, high speed planing can be traditionally addressed with a flat bottom and the propeller portion of the outboard motor extending well below the flat bottom. Additionally, the hull must be designed and constructed in a manner which allows operation in rough sea conditions with waves coming from the bow, the stem, or either side. Rough sea operation is sometimes addressed with a deep V hull shape. These design considerations sometimes increase the draft of a boat.  
      Morejohn, in the &#39;341 patent, proposed a solution to these competing design criteria by including a tunnel in the bottom of a shallow draft boat. The tunnel allows one to place an outboard motor higher with respect to the hull of the boat than permitted by conventional designs. The tunnel is relatively short with respect to the overall length of the boat, has a small volume, and is provided with a recess at its leading end and a vent communicating between the recess and the port in the transom above the water line. However, in the Morejohn design, the bow of the boat defines a V hull shape of conventional boats, thus cutting a deeper draft than is desirable.  
      Another shallow draft boat was proposed by May in U.S. Pat. No. 4,652,245. May taught a shallow draft boat which could be used for coastal fishing or shrimping operations. The boat included 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 was preferably of decreasing cross-sectional area along its length so that prop wash created by the motor was forced through a progressively smaller volume, thus producing an uplifting force adjacent the boat&#39;s stem. Hence, the boat rode on the motor prop and flattened stem areas of the hull with very little draft. The trough construction also facilitated turning by creating a wall of water which must be shifted right or left; this allowed the bow to come around very quickly for easy handling in restricted areas. However, as with the Morejohn design, the axial trough of May began some distance aft of the bow, and in addition to the additional draft, also tended to make the craft more difficult to control at speed as it cut through the water.  
      Thus, there remains a need for a shallow draft boat which provides minimum draft at speed and at idle, and further provides a stable, easily controlled aspect as the craft moves through the water. The present invention is directed to solving this need in the art.  
     SUMMARY OF THE INVENTION  
      The present invention addresses these and other needs in the art by providing a main channel which extends from the bow region of the boat through to the transom region of the boat. As used herein, the term “bow” refers to the forward hull surface of the boat, whereas the term “prow” refers specifically to the forewardmost tip of the boat.  
      Preferably, the axially extending main channel is of substantially uniform width along most of its length. A term “shoulder” will be used herein to refer to the point along the hull at which the boat begins to taper at the bow. Preferably, the channel will also begin to widen or flare at substantially the same point along the axis of the boat at the shoulder. The channel thus extends to the bow at a point aft of the prow, while expanding in width. In this way, the unitary hull simulates a pair of side-by-side twin hulls or pontoons, offering the benefits of enhanced buoyancy and stability, which are not offered by the V-hull designs of other shallow draft boats in the art.  
      The present invention also provides relatively short channel at the transom of the boat, extending above the main channel. This relatively short channel may be referred to herein as a “shooter” or cooling channel. The purpose of this cooling channel is to direct cooling water to the input port of an outboard motor. It should be noted that, without the cooling channel, the propeller of the outboard motor would have to be lowered by a distance equal to the height of the cooling channel, thereby increasing the minimum depth at which the boat may be safely operated.  
      These and other features and advantages of the present invention will be readily apparent to those of skill in the art from a review of the following detailed description along with the accompanying drawing figures.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a bottom plan view of a shallow draft boat of this invention.  
       FIG. 2  is a side, elevation view of the shallow draft boat in partial section.  
       FIG. 3  is a top view of the boat illustrating an outboard motor receiving recess.  
       FIG. 4  is a stern elevation view of the boat.  
       FIG. 5  is a section view of the boat, taken along section lines  5 - 5  of  FIG. 2 . 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT  
      As shown in  FIGS. 1 and 2 , a shallow draft boat  10  includes a main channel  12  extending substantially the length of the boat  10 . The boat has a transom  14  with a motor recess  16  defined therein. The main channel  12  opens into the recess  16 , so that an outboard motor (not shown) mounted within the recess  16  does not have to extend down into the water as far as it otherwise would have to, but for the channel  12 .  
      The boat includes a starboard gunwale  20  and a port gunwale  22 . For most of the length of the boat, the gunwales  20  and  22  are parallel to one another. However, the perimeter of the boat includes a shoulder  24 , as previously defined. At the shoulder, the boat begins to define a tapered edge  26  along the starboard side and a corresponding tapered edge  28  along the port side. From the forward edges  26  and  28 , a fairly blunt prow  30  extends.  
      The main channel  12  is of substantially uniform width from an opening  17  into the recess  16  to a point roughly adjacent to the shoulder  24 . Beginning at an initiation point  25  roughly adjacent the shoulder, however, the channel  12  widens in an arcuate fashion until the main channel  12  opens at a point  32  along the bow  34  of the boat (see  FIG. 2 ). Thus, as the boat moves through the water, the main channel  12  receives water at the opening of the main channel at the point  32  and the received water moves along the length of the main channel to provide side-to-side stability for the boat as it moves.  
      The main channel  12  serves a number of other functions, in addition to the function of stability as just described. For example, any boat moving through the water will aerate the water that it moves through. In the main channel, however, since the channel tapers down from the point  32  back to the point  25 , the water in the main channel is “squeezed”, thereby compressing the air that has been introduced into the water. This reduces the aeration of the water within the main channel, which improves the efficiency of the propulsion of the boat, since the water within the main channel  12  is directed aft into the propeller blades of an outboard motor. The design also allows the use of more efficient propeller designs and raises the engine higher in relation to the hull bottom, providing even shallower draft operations of the boat.  
       FIG. 3  depicts a top down view of the stern of the boat  10 .  FIG. 4  shows the stem of the boat, and  FIG. 5  shows a section view along section lines  5 - 5  of  FIG. 2 . With the main channel  12  extending axially through the boat from end to end, a starboard pontoon  40  and a port pontoon  42  are formed. This feature provides the benefit of a split hull, with the hull formed of a single, continuous material.  
      Further, each of the starboard pontoon and the port pontoon defines a concave surface, with each concave surface slanting inwards toward a centerline  44  of the boat ( FIG. 1 ). The outer edges of the pontoons  40  and  42  also include concave arcuate surfaces  40 ′ and  42 ′, respectively, for greater straight-line travel stability.  
      Although the present invention includes port and starboard pontoons  40  and  42 , this design is not a catamaran because the main channel  12  includes a ceiling  46 . Furthermore, the ceiling  46  is not parallel to a bottom-most extent  48  of the boat, but rather slants downward from the bow to the stem, as shown in  FIG. 2 . If a ceiling height h is defined as the vertical distance between the ceiling  46  and the bottom-most extent  48 , then a forward ceiling height h f  defines a ceiling height at the forward end of the boat and an after ceiling height h a  defines a ceiling height at the aft end of the boat, with h f  greater than h a . This feature of the invention provides a lift force vector to the stem of the boat, thereby keeping the boat more level at speed and permitting the boat to move at higher speeds through shallower water.  
      Preferably, the boat  10  as shown in the drawing figures is formed as a single molding of a composite or fiberglass material. This feature provides greater buoyancy to the vessel, and the vessel can be completely submerged and still float.  
      The present invention also includes a secondary channel  50 , referred to as a cooling or “shooter” channel. An outboard motor includes a cooling water intake port at about 4 to 9 inches above the centerline of the propeller shaft of the outboard motor. The cooling channel  50  directs cooling water to a height above the ceiling  46 , thereby raising the height at which the outboard motor may be mounted to the boat and still receive adequate cooling water. The cooling channel preferably includes a horizontal ceiling  52  for the aftermost portion of the channel, and a slanted ceiling  54  for the forwardmost portion of the channel, to minimize the amount of turbulence and drag introduced by the channel. The width of the cooling channel may also taper at the forwardmost portion of the channel for the same reasons, if desired. The cooling channel feature of the invention further lowers the minimum depth at which the boat may be operated. Note also that, if the cooling channel were to be extended the length of the main channel, then a great loss of efficiency of the propulsion system of the boat would result.  
      As described herein, the present invention provides enhanced stem lift, which improves high speed performance of the craft. Added stern lift also allows one to travel at extremely slow speeds which is desirable to fishermen, since at slow speeds one is more able to spot schools of fish on flats and to stop before one runs through and spooks the fish. Slow speeds also give the pilot added time for maneuverability, to avoid obstacles that might ground or damage the vessel and to maneuver around schools of fish. The hull design shown and described herein provides the capability of holding on-plane in as little as 5 inches of water and a firm bottom at speeds well under 10 miles an hour, verified with GPS. Further, these capabilities of the present invention were accomplished with a standard, out-of-the-box outboard engine, with no modifications to the cooling system. Additionally, the more stern lift that is created, the shallower a boat will go and since the stern (having more weight due to the placement of the engine) travels further below the water surface, any lift at the stern results in significant increases in a boat&#39;s shallow-water capabilities.  
      The principles, preferred embodiment, and mode of operation of the present invention have been described in the foregoing specification. This invention is not to be construed as limited to the particular forms disclosed, since these are regarded as illustrative rather than restrictive. Moreover, variations and changes may be made by those skilled in the art without departing from the spirit of the invention.