Planing power boat

Abstract

The present invention over-comes the prior art deficiencies by, in part, defining a hull bottom that decreases the total resistance and thereby reduces the propulsion power needed to propel a boat of a certain weight to a given speed. The invention separates the functions of the planing process resulting in a hull with staged longitudinal steps wherein each step consists of a fully defined hull underbody with a chine and bow and stern. Each intermediate chine describes a supplemental planing surface which is designed to lift the hull dynamically and to position the hull on the next narrower step that supports the weight of the boat and creates the forces needed to further lift the hull to the next narrower chine in two or more stages depending upon the size and weight of the boat to lift the hull to the central planing surface to achieve the desired top speed. The hull for each step is described by its chine, hull bottom, deadrise angle, bow and stern dimensions optimized to the “ideal beam”(Ref. 7) to cover the range of speed of its stage of supplemental planing surfaces in the planing process by controlling the trim angle and vertical rise in the center of gravity. The hull bottom of each supplemental and central planing stage is separated by a vertical step extending longitudinally from bow to stern with the deadrise angle of the hull bottom of each step equal to or greater than the lower narrower hull stage below it. As a result the trim angle of the speed range for each stage can be optimized to fall in the range of 3.5 to 5 degrees to provide the least total resistance (Ref 5) (the combined wave making and friction resistance) over the range of operation for the hull of each stage and for the overall operating range covering all stages from rest to top speed. The number of supplemental planing surface stages, if more than one, will depend primarily upon the top speed to be attained and the overall length and width of the boat. An intermediate lower speed for long term operation as a cruising speed may be selected to dictate a staging point to assure optimized efficiency at this intermediate stage; such as, to optimize the efficiency at the cruise rating of the propulsion system for extended range (based upon the fuel tankage capacity).

What is claimed per new claims 5 to 19 is:  
     
         5 . A planing boat compromising a hull of greater length than breadth between its sides, means to drive the boat forward in substantially the direction of its greater length with the exterior bottom planing surfaces of its hull consisting of a series of two or more sequentially stacked chines with the widest chine formed by the hull side and the widest and uppermost hull bottom being joined to one or more ever narrower chines separated by vertically walled steps between each chine extending longitudinally from the transom to the bow whereupon when increasing speed the lift created by hydrodynamic forces acting on the hull causes the hull to rise until the widest and uppermost hull bottom's chine drys out by being clear of the spray and wake from the chine of the next narrower hull in stages to optimize the trim angle for each stage and depending upon the number of chine steps needed to cover the speed range from at rest until the speed is achieved whereupon the hull will be supported by the narrowest planning surface hull from that speed and above and with each stage of the planing sequence designed to operate at a trim angle at or near the 3.5 to 5 degree optimum range and the number of stages determined by the design top speed with the option of operating at long periods of time at any stage such as to match an engine rating intended for continuous operation.  
     
     
         6 . I claim a boat in accordance with  claim 5 , in which the low resistance advantages of a narrow hull do not compromise the stability at rest wherein the narrower chines are submerged and the widest hull bottom providing a major contribution to the magnitude of the restoring moment from heeling (side to side tipping.  
     
     
         7 . I claim a boat in accordance with  claim 5 , in which the height in inches of the vertical steps is at least 1.5 times the length of the chine (Lp) measured between perpendiculars taken at the transom and bow intersections divided by the value 21.0 wherein the step is constant from about amidship aft and progressively narrows a from amidship forward until blending into the bow wherein each step contributes to the drying out of the chine above when any portion of the controlling chine's vertical step is at or above the water's surface.  
     
     
         8 . I claim a boat in accordance with  claim 5 , in which the angles (deadrise) of the hull bottoms measured at the transom for each planing stage shall be equal to or less than that of the wider hull bottom surface above it wherein the lower most narrow central planing surface deadrise angle may range from negative to positive but the deadrise angles above the central planing surface must be positive and each surface equal to or greater than the deadrise angle below it for spray direction control and to enable the surface above the controlling chine stage to dry out at the planing stage where the hull bottom surface below it controls the planing performance and the behavior of the water being impacted.  
     
     
         9 . I claim a boat in accordance with  claim 5 , in which the central planning surface controls the top speed performance by using the lift of the stages above it to cause them to dry out sequentially at progressively higher speeds and position the central planing surface so that its chine and vertical step are just below, at of above the water surface so that the spray from the central planing surface is directed away from the hull without wetting any of the surfaces above under most sea conditions wherein the hull when so positioned will be running at a trim angle of from 3.5 to 5 degrees and be achieving the least total resistance and the highest attainable hull efficiency at each stage in covering the range in speed from at rest to the design top speed.  
     
     
         10 . I claim a boat in accordance with  claim 5 , in which the number of planing stages is two or more to accomplish the separation of the planing functions by lifting the hull with increasing speed to position the hull on the central planning surface when approaching and operating at the design speed and to control the trim angle range at the top speed and for each stage between from 3.5 to 5 degrees thereby assuring the least total resistance for each stage is covering the full speed range.  
     
     
         11 . I claim a boat in accordance with  claim 5 , in which the staged planing steps are employed to control the trim angle of each planing stage not to exceed 5 degrees, maintain a safe margin to avoid porpoising and thereby avoid the high trim angles and correspondingly high total resistance at low speed characteristic of wider hulls which may control the power needed to progress from at rest to higher speeds (called, “getting out of the hole”) as well as to prevent operation at trim angles below 3.5 degrees to minimize the wetted caused frictional resistance.  
     
     
         12 . I claim a boat in accordance with  claim 5 , in which the longitudinal steps in separating the staged progressively narrower hull bottoms soften the impact from reentry from being launched airborne in rough water by absorbing the energy of reentry in stages, first by the narrow central planing surface followed by the successively wider hull chines each separated by a step wherein higher speeds in rough water can be tolerated by the helmsman and crew when continued operation is critical to the mission or alternatively the prior art boat speed can be tolerated with shallower hull bottom dead rise angles of in the range of the 12.5 degrees without sacrificing the softer reentry impact forces enjoyed with prior art deep V mono-hulls having dead rise angles in the 24 degree range.  
     
     
         13 . I claim a boat in accordance with  claim 5 , in which the focus upon developing the least total resistance at top speed does not sacrifice potential for equally efficient operation at speeds below hull speed (below a speed of about 1.33 times the square root of the water line length) as is the compromise of prior art hulls which employ transverse steps and of hulls employing spray rails or underwater foils arranged to interrupt a smooth flow of water along the hull underbody generating eddies and associated losses.  
     
     
         14 . I claim a boat in accordance with  claim 5 , in which the dimensions and deadrise angles of the chine for each stage may employ proven and documented tow tank and computational fluid dynamics developed models assuring the low total resistance characteristics from friction and wave making and assuring each stage to be dynamically stable against porpoising over the operating speed range of each of the planing stage and for the overall boat in the operating from at rest to the design top speed.  
     
     
         15 . I claim a boat in accordance with  claim 5 , in which the ratio of the length is greater than the breadth (beam) over the range of from 2.0 to 20.0 to one.  
     
     
         16 . I claim a boat in accordance with  claim 5 , in which each stage of longitudinally stepped chines describes the bottom portion of a complete hull bottom symmetrical about the centerline with a bow, a stern and a chine; wherein, the shape of these surfaces may be original or follow those prescribed in published resistance tests or those of a systematic series of planing hull forms or within the limits established to enable the use of hydrodynamic performance predictions to determine total resistance (wave making and friction), hull rise (lift), trim angle for each stage needed to cover the design speed range; wherein, the total resistance of each stage is minimized and the trim angles of each stage optimized for least resistance and capable of lifting the boat in stages until the top speed is reached and the hull surfaces and chines above the central planing surface dry out under normal operating conditions.  
     
     
         17 . I claim a boat in accordance with  claim 5 , in which one or more of the stages of the longitudinal stepped planing hull is also optimized for an intermediate speed below the top speed for low total resistance planing at optimum efficiency or maximum range at an operating point expected for long term operation at a power boat engine's continuous operation rating or for a particular long term expected point of sailing for a planing sailing boat.  
     
     
         18 . I claim a boat in accordance with  claim 5 , in which the vertical steps running longitudinally are integrated with the longitudinal frames (bilge stringers) enabling the employment of the present invention without introducing a potential weight penalty for the corresponding structure.  
     
     
         19 . I claim a boat in accordance with  claim 5 , in which the hull surfaces may be developed for single plane bending to allow hull construction with materials such as steel plate or plywood in addition to materials that can be molded or formed into three dimensional shapes without restriction.