Abstract:
A boat hull configured to create a desired wake shape through a combination of two distinct hull types that interact with the water flow at specified moments. Controlled shaping of the wake shape is achieved through redirection of water flowing across the transom of the main hull, onto a secondary transom of a secondary “diffuser” suction hull that creates a negative pressure that sucks the aft portion of the boat hull into the water, thereby immersing the secondary transom into the water where it can effectively interact with the water and “carve” the desired wake shape desirable for wake surfing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority to U.S. Provisional Patent Application Ser. No. 61/648,833, filed May 18, 2012 and U.S. Provisional Patent Application Ser. No. 61/642,823, filed May 4, 2012, which are hereby incorporated by reference herein in their entirety, including any figures, tables, or drawings. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to boat hulls, and in particular to a towboat boat hull manipulating various wakes popular in water sports activities. 
       BACKGROUND OF THE INVENTION 
       [0003]    Towboats are a certain type of boat used for water sports, such as skiing, wakeboarding, or most recently, wake surfing. Towboats designed for towing skiers in water sports activities such as wakeboarding, water skiing, or wake surfing are generally designed with hull bottoms and hull forms that create distinct wake shapes, that cater specifically to the desirable characteristics. Wake surfing is a relatively new water sport, and it is vastly different than other water sports such as skiing or wakeboarding. Contrary to other water sports, wake surfers do not hold onto a tow rope that is attached to the boat. Rather, they utilize a wake board to surf a wake that is created by the towboat moving through the water. However, desirable wake characteristics for a wake surfer are vastly different than the characteristics desired by a wake boarder, or skier, since wake surfers prefer to “ride” the cresting wake close behind the boat without the use of a towrope, and traditional water skiers usually prefer a softer and flatter wake, while the wake boarder generally prefers a tall wake that act as a “ramp” to jump off of when crossing the wake behind the boat. Wake surfing is a new type of water sport that is becoming extremely popular, and the desired wake shape is rather difficult to achieve with traditional boat hulls. 
         [0004]    Since wake surfing is relatively new, and the characteristics of the desired wake shape are very specialized, building a purpose-built boat hull useful for only this type of water sport would limit the boat&#39;s utility for other tow boating activities, such as skiing, and wakeboarding. Building a purpose-built wake surfing boat would also severely hinder the boat&#39;s performance for pleasure cruising, as the wake surfing boat&#39;s hull characteristics would negatively affect its ability to travel at moderate or high speeds. Consequently, there is a need to design a boat hull that can adequately create distinctive wake shapes for both wake surfing water sports, and traditional skiing and wakeboarding water sports. 
       BRIEF SUMMARY 
       [0005]    Embodiments of the present invention are directed to boat performance and desired wake shaping through a combination of two distinct hull types that interact with the water flow at specified moments. Controlled shaping of the wake surfer wake is achieved through redirection of water flowing across the transom of the main hull, onto a secondary transom of a secondary “diffuser” suction hull, that by careful shaping, will achieve a negative pressure in which to suck the aft portion of the boat into the water, thereby immersing the secondary transom into the water where it can effectively interact with the water and “carve” the desired wake surfing wake. In keeping with the teachings of the present invention, a boat having a hull with a transom extending across the aft side of the hull may include a secondary running surface extending aft of the primary hull with a diffuser type of design that will cause suction when water flowing off of the initial transom is redirected, and adhered to the secondary suction hull. The secondary suction hull includes a transom of a specific shape that will “carve” the desired wake surfing type of wake into the water as the boat moves through the water. The secondary suction hull may be defined as a diffuser surface that begins aft of the primary hull transom extending longitudinally, and slightly above the primary hull bottom, so that the water flow will break cleanly off of the primary running surface at the primary transom, and will not interact with the secondary suction hull unless the water flow is specifically redirected. The secondary suction hull extends slightly upward toward its exit portion at the transom, so that its surface area increases and the water flow is redirected along its bottom surface, causing a measurable negative pressure at the secondary hull bottom. A pair of pivotal tabs (by this inventor—application Ser. No. 12/626,280, which is hereby incorporated by reference) are positioned at the primary transom with the axis of rotation perpendicular to the hulls centerline, wherein the forward edge of the tab is level with the primary hull bottom in its neutral position. In the neutral position, the water flow will continue aft from the primary hull surface, and under the pivotal tabs, where the flow will have no further interaction with any part of the boat, specifically the secondary suction hull, as this would prevent normal operation of the boat. The pivotal tabs are positioned so that the leading edges can rotate upward, where their trailing edges will interact with the water flow and divert the water flow down, keeping the water flow further away from the secondary suction hull when the hull speed is low, and the secondary suction hull function is not desired. The pivotal tabs are also positioned so that the leading edges rotate down, and into the water flow coming off of the primary hull at its transom, thereby directing the water flow on the top surfaces of the pivotal tabs. The water flow coming off of the tops of the pivotal tabs is redirected to act on the secondary suction hull that has drastically different performance qualities than the primary hull. The suction generated by the secondary suction hull will inherently change the running attitude of the boat, with a very deep stern down condition that will increase as more power is applied. This performance characteristic is in stark contrast to boats utilizing weight from a typical water ballast system where increased speeds cause the desired wake surfing wake shape to diminish. Additionally, the transom shape of the secondary suction hull is shaped so that it interacts with the water flow in a manner that specifically “carves” and shapes a desirable wake for wake surfing. This is also in stark contrast to typical tow boats utilizing weight from water ballast systems, as their primary hull and transom shapes are designed for high speed performance and general boat handling characteristics that have different qualities than a specific wake surfing type of hull, and their additional weight only lowers the standard transom lower into the water to change the position of the wake table&#39;s distance from the boat, with no actual method of “carving” a wake shape. This embodiment will allow the boat to utilize both a standard type of transom for most boating needs, and a specialized wake shaping secondary hull for specialized wake surfing qualities. 
         [0006]    Those skilled in the art may employ various combinations of the secondary suction hull and method to redirect the water flow once having the benefit of the teachings of the present invention. By way of example, a single pivotal tab may be positioned at a transom of primary hull with a flat bottom, where dividing the pivotal tabs to interact with two planes of a typical V style hull is not necessary. In addition, other methods of redirecting water flow to a secondary hull with vastly different characteristics may be achieved. 
         [0007]    The secondary suction hull may be positioned in a manner where the water flow is redirected by a rotating tab recessed into a pocket in the primary hull bottom. Alternatively, water flow from the primary hull may be redirected onto the secondary suction hull from deflectors mounted on the sides of the primary hull. 
         [0008]    Furthermore, a secondary suction hull may be separately affixed to a conventional hull in order to achieve similar results. 
         [0009]    As will be detailed later in this specification, the transom shape of the secondary suction hull when viewed from the rear view, will differ greatly from the primary hull transom shape, as the transom shape necessary for controlling a wake surf style wake is usually not conducive to high speed operation necessary in other types of water sports where a flatter wake is desirable. The transom shape of the primary hull will serve to create the optimal performance for normal operation, and water sports activities, such as skiing and wakeboarding. 
         [0010]    In order to achieve desirable wake surfing wake shapes, the secondary suction hull transom profile may curve with complex shapes to resemble the profile of a wave in section view in order to create smaller wakes that crest further away from the transom of the boat so that the wakes can be ridden by more than one wake surfer at a time. This type of secondary transom may have a similar deadrise angles to the primary hull transom angles, when view in section. 
         [0011]    Additionally, the secondary suction hull may employ an inverted deadrise angle, that would create an immense single wake, where the transom surface is higher in the center, than at its outside edges. This embodiment may create a large diffuser at the suction hull, that combined with a curved section that transitioned down at the outboard edges near the chines, would cause the wake shape to “fold over” and curl. This wake shape would be extremely desirable for single riders desiring a large crest to surf close to the boat. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0012]      FIG. 1  is a side elevation view of a tow boat having two distinct running surfaces with the pivotal tab in place; 
           [0013]      FIG. 2  is a plan view of a tow boat hull having two distinct running surfaces with the pivotal tab in place; 
           [0014]      FIG. 3  is an enlarged partial stern elevation view of the tow boat of  FIG. 1  shown without the pivotal tab in place; 
           [0015]      FIG. 4  is an enlarged partial bottom plan view of the tow boat stern of  FIG. 1  having two distinct running surfaces shown without the pivotal tab in place; 
           [0016]      FIG. 5  is an enlarged partial stern elevation view of the tow boat of  FIG. 1  shown with the pivotal tab in place, in its neutral position 
           [0017]      FIG. 6  is an enlarged partial stern elevation view of the tow boat of  FIG. 1  shown with the pivotal tab in place, with its leading edge in the upper position 
           [0018]      FIG. 7  is an enlarged partial stern elevation view of the tow boat of  FIG. 1  shown with the pivotal tab in place, with its leading edge in the upper position 
           [0019]      FIG. 8  is a stern elevation view of the tow boat of  FIG. 1  shown with two distinct running surfaces shown without the pivotal tab in place; 
           [0020]      FIG. 9  is a partial cross-sectional along line A-A in  FIG. 8 ; 
           [0021]      FIG. 10  is an enlarged partial stern elevation view of a hull with two distinct transom shapes and pocket for the actuator of the pivotal tab assembly, with an alternate transom shape in keeping with the teachings of the present invention; 
           [0022]      FIG. 11  is a stern elevation view of a hull with two distinct transom shapes and pocket for the actuator of the pivotal tab assembly, with an alternate transom shape in keeping with the teachings of the present; 
           [0023]      FIG. 12  is a perspective view of a boat creating a wake having specific cross-sectional shapes and curls behind the boat; 
           [0024]      FIG. 13  is a perspective view of a boat creating a wake having specific cross-sectional shapes and curls behind the boat; 
           [0025]      FIG. 14  is a perspective view of a boat creating a wake having specific cross-sectional shapes and curls behind the boat; 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    The present invention will now be fully described with reference to the accompanying drawings, in which various embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the invention to those skilled in the art. 
         [0027]    Referring initially to  FIGS. 1-8 , embodiments of the present invention are directed to performance of a tow boat  10  and resulting creation of a wake  00  through a redirection of water flow  7  flowing from a primary hull  15  to a secondary suction hull  20  and the wake shaping effects of a specialized secondary transom  25 . In keeping with the teachings of the present invention, the boat  10  is herein described as having the hull  15  with a keel  13  extending fore and aft, a chine extending fore and aft defined by a transition from the hull bottom panel  15  at  11 , as seen in  FIG. 4 , and its outer chine edge  12 , and a transom  14  which extends transversely across the hull bottom panels  15 . As illustrated with reference to  FIGS. 1-8 , one embodiment of the present invention includes a secondary suction hull  20  extending aft of the primary hull  15 . The secondary hull  20  is described as having a secondary keel  29  extending fore and aft, an inner diffuser edge  21  extending fore and aft, an outer diffuser edge  22  extending fore and aft at a height lower than the inner diffuser edge  21 , and a secondary transom  25  which extends transversely from the hulls  10  centerline  50  to the intersection of the side of the hull at  26 .  FIG. 9 , by way of example, shows a section view of  FIG. 8 , where the secondary hull  20  may be defined as having an entrance portion  16  positioned above transom  14  at a height  19  sufficient to break the water flow  7  and inhibit interaction with the secondary hull  20 , and extend aft to an indentation  17  where water flow  7  will be reattached to hull surface  20  when redirected by pivotal tab  90 . 
         [0028]    As illustrated with reference to  FIGS. 3 ,  8 ,  9 ,  10 - 11 , a recessed pocket  30  may be included to allow clearance for the pivotal trim tab  90  mechanism. 
         [0029]    As illustrated with reference to  FIG. 7 , the secondary hull  20  will achieve its desired effect of sucking the aft portion of the secondary hull  20  downward by redirecting water flow  7  off of the primary transom  14  onto the top of pivotal trim tab  90  whereby water flow  7  will reattach to secondary hull  20  where the surface is angled upward and with a rocker concave section as illustrated in  FIG. 9   
         [0030]    As illustrated with reference to  FIGS. 8 and 11 , the secondary hull surface  20  will hold its suction to the outer corners of the hull  10  by lowering the outer diffuser edge  22  past the upper edge of the secondary hull panel  20  at the inner diffuser edge  21 , where outer diffuser edge  22  will function as a “seal” to the water flow  7  preventing air from entering a concavity  35  formed within the secondary running surface or hull  20  and breaking the suction. As illustrated with reference to  FIGS. 1-11 , the outer diffuser edge  22  transitions into the secondary transom  25  at the corner  26  of the hull  10  thereby sucking the secondary transom  25  into the water flow  7  where it can manipulate the water flow to create the desired wake shape. 
         [0031]    As illustrated with reference to  FIGS. 10 and 11 , in one embodiment the secondary suction hull  20  includes a secondary keel  29  that curves upward so that the aft end of the keel  29  is above inner diffuser edge  21  when viewed in elevation to warp the secondary hull surface  20  into a concavity  35  defined by the inner and outer diffusion edges of the secondary transom  25 . The lower corners  27  of the secondary transom  25  would create a forward face in the water flow  7  that would serve as an ideal surfing wake. It is expected that alternate transom shapes will become apparent to those skilled in the art now having the benefit of the teachings of the present invention. Such alternative, which perform the same function, in substantially the same way, with substantially the same result are considered to be within the scope of the subject invention. 
         [0032]    As illustrated with reference to  FIG. 12 , the wake shape with the water flow  7  redirected to act upon the secondary hull  20  will be determined by several factors including the secondary transom shape  25  seen in  FIGS. 1-9 , hull speed, and prop wash  82  which is caused by the accelerated water coming off of the propeller. The prop wash  82  usually exits a certain distance from the boat  10 , and is often referred to as the rooster tail  82 . The wake shape will have different sections and qualities at different distances from the boat  10 . By way of example, the secondary transom  25  and the edge of the secondary hull  26  will create the initial shape of the wake as the boat travels over the water and the water flow converges together afterward. A vertical face  83  of water created by the side of the hull  26  can be defined by its upper edge  81  which is determined by the top level of the water that the boat is riding through and the lower corner  80 , which is carved by the outer diffuser  22  as it sucks down and contacts the water. The water flow  7  coming off of the transom  25  will ultimately create the trough  86  that will converge back together some distance from the boat, depending on the hull speed. The prop wash  82  will emerge from under the water flow  7  and interact with the vertical face  83  creating a curl  85  that will be a desirable wake shape for a wake surfer. Additionally, the trough  86  specifically shaped by the secondary transom  25  will present an ideal trough  86  with two opposing faces  83  in which to surf in between at a higher speed more commonly found in naturally breaking waves. 
         [0033]    As illustrated with reference to  FIG. 13 , the wake shape with the water flow  7  redirected to act upon the secondary hull  20  will also be determined by several factors including a modified secondary transom shape  25  as seen in  FIGS. 10 and 11 , hull speed, and prop wash  82 . The prop wash usually exits a certain distance from the boat  10 , however, the suction force created by the secondary hull  20  and its specialized secondary transom  25  will lift the water flow  7  up to blend in with the rooster tail  82  creating a large swell  87 . The swell will have different sections and qualities at different distances from the boat  10 . By way of example, water exiting the transom  25  through the concavity  35  will be manipulated by the vertical edge  27  and will form a secondary vertical face  84  on either side of the swell  87 , as shown in  FIG. 13 . A vertical face  83  of water created by the side of the hull  26  can be defined by its upper edge  81 , which is determined by the top level of the water that the boat is riding through and the lower corner  80 , which is carved by the outer diffuser  22  as it sucks down and contacts the water. When the vertical face  83  converges back into the larger secondary vertical face  84 , it causes the lower edge of secondary vertical face  84  to trip and create the most ideal curl face  85  with an outer trough  89  in which two wake surfers can utilize. The ability to have two wake surfers able to surf next to each other is a feature not found anywhere in the industry or nature. 
         [0034]    As illustrated with reference to  FIG. 14 , the wake shape with the water flow  7  not directed to act upon the secondary hull  20  will be that of an ordinary tow boat with a standard hull  15  and primary transom shape  14 . With the pivotal trim tab  90  in the neutral position or in a position with its leading edge above the primary transom  14  the water flow will bypass the secondary suction hull  20  allowing greater speed and a flatter trough  86  that is preferred by water skiers. Additionally, greater speeds attained with the primary hull  15  will position the rooster tail  82  farther back which is ideal for the rope length utilized for wakeboarding. 
         [0035]    As will become apparent to those skilled in the art now having the benefit of the teachings of the present invention, various combinations of the secondary suction hull  20  and the secondary wake shaping transom  25  can be employed depending on the wake to be achieved. By way of example, the secondary transom  25  may embody different sections to create specific wake shapes not mentioned in these teachings. 
         [0036]    Many modifications and other embodiments of the invention will become apparent to one skilled in the art after having the benefit of the teachings presented in the included descriptions and drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments within the scope of the invention.