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).

Description

RELATED APPLICATION

[0001] Amendment to patent application Ser. No. 10/308,363 filed by the present applicant on Mar. 4, 2004. Provisional Patent Application Serial No. 60/338,632 filed by the present applicant on Dec. 3, 2001 (priority date claimed for the present application and this amendment).

FIELD OF THE INVENTION

[0002] The invention relates to power boats having planing hulls.

BACKGROUND OF THE INVENTION

[0003] Fast planing power boats have long had racing as their objective (e.g., the famous Cigarette boats). Boat speed became important for other purposes later, such as, survival (in the case of rum running during U.S. National Prohibition), and for military purposes. As World War II approached the renowned PT boats were developed for U.S. and Allied use, each driven to planing speed by three powerful inboard engines, and planing on an essentially V-shaped bottom surface. Generally similar boats were later developed for pleasure and commerce, the latter mostly using twin Diesel engines for propulsion. Some were developed for off-shore cruises by parties wishing to go out fast, fish awhile, and then return fast, within a day for the whole cruise.

[0004] As fuel costs have risen, interest in fuel efficiency has increased for all kinds of power boats, including planing boats. Owners of smaller planing boats (such as outboards and inboard-outboards) are likely to be less interested in fuel efficiency than owners of larger power boats, but owners of both sizes are interested in increasing speed through hull improvements with equal to or lower power ratings. A time honored way of doing this is to make it easier to drive the hull forward by increasing the ratio of length to beam, but this has the disadvantage of reducing stability against rolling (sidewise tilting) of the hull while at rest or running at sub-planing speeds. It also reduces space inside the hull.

[0005] The stability problems of increasing the length to beam ratio are sometimes dealt with by going to a multihull construction, but that brings in new problems. It is preferable to retain monohull construction, subject to improving it to optimize planing speed, fuel efficiency and stability against rolling.

[0006] Fast planing power boats where high speed is the prime objective such as for racing, patrol and military purposes exampled by the now famous Cigarette boats, PT boats and the new MK V Special Operations Craft have the common characteristic of having a very narrow width(beam) for their length. The MK V, for example, is 82 feet long with a 17.5 foot maximum beam at its deck (even narrower at the at-rest waterline) for a ratio of 4.68 length to beam. A Hp/Rough Rider Cigarette racing boat is 46 feet long and has a narrow beam of 8 feet for a length to beam ratio of 5.75.

[0007] Reference 7 describes a method developed by the US Navy David Taylor Model Test Basin personnel to determine the Ideal Beam for Different Speeds. The factors they identified included the design top speed, the length and position of the center of gravity of the boat along that length, and the total weight (displacement) of the boat. The Ideal Beam calculation for the MK V indicates a beam at the deck of about 16 feet which is close to the 17.5 design value. For the 46 foot Cigarette, however, at its much higher relative speed the Ideal Beam would be less than 3′ compared to the already narrow design of 8 feet. A 3′ beam would be unstable at rest and restrict the interior space needed for crew and engines, yet finding a way to incorporate the 3′ beam into the planing hull shows promise for performance improvement. Optimizing the total resistance of hull in accordance with the procedures of Ref. 2, 5 & 6, guided by the narrow hull from the Ideal Beam analysis, Ref. 7, yields a dramatically lower value. The tests per Ref. 1,2,3 &4 confirm these lower values as long as the hull dimensions are adhered to, the hull is complete with a chine from bow to stern and hull bottom profile and deadrise angles controlled, bottom loading within the range tested, longitudinal center of buoyancy within the range of the tests and entire geometry of the entire hull kept within the boundaries of the tests and calculation procedures. Only then will the boat behave as predicted for all points of speed and the predictions be assured.

[0008] Another example is for a 16 foot runabout sport boat used primarily for water sports. Such a boat typically weighs about 1200 pounds and has a 6 foot beam enabling side by side seating for two. With a top speed goal of 35 mph the Ideal Beam indicates a beam of 2 feet (length to beam ratio of 8). The performance of boats where the actual beam deviates from the ideal by large amounts is seen in the higher than optimum resistance from friction and wave making required to propel the boat. When the function of the boat demands beam widths higher than optimum, the power to drive that boat will also be higher than the optimum. Finding a way to incorporate the 2′ beam into the planing hull shows promise for performance improvement.

[0009] Prior art, model tests and analysis techniques have suggested the benefits of narrower hulls for high speed. The positioning of spray rails and employment of a central planing surface (pad) of varying configurations are currently used with varying results that hint at the potential should an optimization process be revealed, per the present invention.

[0010] Two examples of the impact the present invention has on reducing the power needed to achieve a target speed are shown below for a trailerable fishing boat with an overall length of 24.42° and an ocean going sport fishing boat with an overall length of 50.61′(shown in FIGS. 1 through 8): 1 Boat Length 50.615′ 24.42′ Design Weight 42,500 lbs 2804 lbs Top Speed Target 40 knots 62.5 knots Maximum Beam 15.17′ 8.0′ Prior Art Reference Ocean 48 Maverick 21 Prior Art Power - SHP 1600 225 Ideal Beam, Ref 7 10.6′ 1.4′ Present Invention: Planing Stages 2 4 Central Planing Surface Beam 9.0′ 1.24′ Power-SHP 1023 141.2 SHP Improvement - % 36% 37%

[0011] Ref. 8 is another source used to check the prior state of the art performance of power boats and confirm the advantages of employing the present invention.

[0012] The narrower the hull the lower the stability against rolling especially noticeable at rest and when running at sub-planing speeds. Also, narrow hulls provide less internal space to perform the functions for which a certain boat would be intended.

[0013] Another direction in the quest of efficient high speed boats has been in the application of one or more transverse steps with various approaches to vent the vacuum created behind a transverse step at higher speeds. Transverse steps create turbulence behind the steps that add resistance at lower, sub-planing, speeds.

[0014] A boat at rest is supported in the water by its buoyancy and the line around the boat intersecting the side of the hull and the water is called the load water line. The characteristics of the underbody of the boat that is displaced at rest will affect the resistance of the boat as it is propelled. The intersection of the side of the hull to the hull bottom forms the “chine”. The angle of the surface of the bottom of the hull relative to the plane of the water surface is called dead rise angle. The intersection of the bottoms of the hull forms the fairbody keel. This is a line closely parallel to the load water line (LWL) but varies with different designs. Any change in the attitude of the bottom of the hull in the Profile view relative to the water surface as the boat is moved from rest is called, “trim angle”. The position of the center of gravity of a power boat hull will be aft of the amidship position and above the LWL. As the boat is propelled, the vertical center of gravity will change. From the at-rest position as the boat is propelled at low speed the vertical center of gravity reduces (sinks). As the speed is further increased the boat begins to rise and the trim angle will increase. This rise and change in trim is a result of the lift forces generated by the force of the water against the bottom of the hull. This force is proportional to the square of the boat's velocity. When the vertical center of gravity has returned to its at-rest position, the boat will have transitioned from the “displacement” to “planing” mode. The relative speed for this transition ranges from a Froude Number of 1.00 to 1.85. (Froude Number is a dimensionless number equal to the speed of the boat divided by the square root of the product of the acceleration of gravity times the cube root of the at rest displacement volume.) The Froude Number range of 1.0 to 1.85 corresponds to a boat speed to square root of water line length of 1.34 to 2.57. The wave created by the bow entry disturbance has its second peak located (and still supporting the stern of the boat) at a speed of about 1.34 times the square root of the water line length (speed-length ratio). The narrower hulls create lower bow waves and have a higher boat speed at the transition into “planing” mode. A US Navy developed planing boat, referred to as Series 62, Model 4669, with a length to beam ratio of 7.0 exhibited a Froude Number of 1.85 to be “planing”. The total resistance to boat displacement ratio of the narrow and wide hulls is about the same when each hull reached their point of zero CG rise, but the velocity of the narrower hull was 71% higher and would have been expected to have a much higher resistance corresponding to this higher speed.

[0015] The narrower hull creates less disturbance and a smaller bow wave peak height at any given speed in the displacement speed range. When the speed of a wider boat exceeds the 1.34 limiting speed-length ratio and the second peak of the bow wave passes beyond the transom, the stern will follow the drop of the valley between the wave peaks. The stern of a wider boat with its higher bow wave will have a deeper valley to drop into with a higher resulting trim angle. To achieve higher speeds the wider boat must be powered to get “over the hump” of the bow wave, also referred to as, “getting out of the hole”. The power needed to pass the hump may be higher than the power needed to drive the boat at top speed! The narrower the hull the lower the bow wave, the shallower the valley between the bow wave and its second peak and the lower the hump. With a length to beam ratio above 5.5 the hump may not be perceivable.

[0016] The lift forces created on the hull bottom are a function of the speed of the boat and the size of the area impacting with the water. The impact of the water on the hull slows (stagnates) the water velocity creating a velocity pressure in relation to the square of the boat's velocity and the stagnation area times the velocity pressure creates the lift force. The location of impact relative to the center of gravity of the boat creates a trimming moment. The location of the propulsor and the angle of its line of thrust relative to the center of gravity also creates a moment. The balance of all of the forces and moments in play determines the trim angle at any given speed when the boat is planing.

[0017] The details of the resistence forces, rise in center of gravity and trim angle can be determined from tow tests. The US Navy David Taylor Model Test Basin is one of the facilities available for conducting such tests. References 1,2, 3 & 4 provide test results of a series of such tests on various hull forms and displacements over a range of speeds. Reference 5, presents procedures to predict these forces, moments, rise in center of gravity and trim angles for hull forms falling within defined parameters. Reference 5 presents the Hydrodynamic Design of Planing Hulls and contains three especially important discussions. Page 87, FIG. 16, shows a tight relationship of minimum drag-lift ratio (minimizing the combined friction and wave-making resistance) to a trim angle range of 3.5 to 5 degrees. FIG. 18, Page 92, presents the dynamic stability (porpoising) limits sensitivity to trim angle and Table I, page 89, presents a equations which enable the prediction of the rise (lift) of a planing hull measured at its center of gravity.

[0018] Reference 4 presented the data and results of systematic Series 62 Parent Model test program. This data included the measurements of the rise at the center of gravity along with the total resistance and trim angle (which correlates with the procedures and data presented in Reference 5).

[0019] References to support hydrodynamic technology employed in the present invention:

[0020] 1. Society of Naval Architects & Marine Engineers, Small Craft Data Sheets, for Design and Resistance Prediction.

[0021] 2. Society of Naval Architects & Marine Engineers, Small Craft Data Sheets D-14, Parent Model for Planing Boat Series (62), Models 4665 through 4669.

[0022] 3. Society of Naval Architects & Marine Engineers, How to Use the SNAME Small Craft Data Sheets, by Clement.

[0023] 4. Resistance Tests of a Systematic Series of Planing Hull Forms, Society of Naval Architects & Marine Engineers, 1963, Clement and Blount @ David Taylor Model Basin.

[0024] 5. Hydrodynamic Design of Planing Hulls, Society of Naval Architects & Marine Engineers, October 1964, Dr. Daniel Savitsky.

[0025] 6. Performance Prediction, Chapter 6, Text 117, Westlawn Institute of Marine Technology, High Speed Power Boats, by John Teale, NA.

[0026] 7. Ideal Beam for Different Speeds, Chapter 2, Text 117, Westlawn Institute of Marine Technology, High Speed Power Boats, by John Teale, NA.

[0027] 8. Power boat Performance Tests, Professional Boatbuilder October/November 2002, Pg. 72, Figure C, Benchmark Achieved by Monohull Boats.

SUMMARY OF THE INVENTION

[0028] The invention separates the functions of the planing process by dividing the surface over the bottom of a planing hull into a central planing surface capable of supporting and lifting the whole weight of the boat while planing, and a pair of supplemental planing surfaces on opposite sides of the central planing surface, capable of supplementing the lift of the central planing surface while getting underway before it planes and lifting the hull to position the central planing surface for the top end of the planing speed range.

[0029] This arrangement of planing surfaces permits use of an optimum length to beam ratio of the central planing surface for it to plane at high speed with good resistance to side wise rolling and positioning the supplemental planing surface above and extending outwardly from opposite sides of the central planing surface where they help to lift the hull and stabilize against rolling at rest or at sub-planing speeds but at planing speed are lifted by the hull to remove their drag while the central planing surface is planing.

[0030] The hull encloses space above the supplemental planing surfaces and thereby provides buoyancy to help stabilize the hull against rolling at sub-planing speeds and at rest.

[0031] The bottom of the hull has the outer periphery of its central planing surface stepped below and joined to the inner peripheries of the respective supplemental planing surfaces by a pair of step risers extending vertically between them and also extending longitudinally and tapering toward the bow of the boat. The step risers close the space between said peripheries to complete the bottom area and have their upward dimensions consistent with the need of the supplemental planing surfaces to be in the water when the boat is at rest or at sub-planing speeds and progressively rising out of it at initial planing speed through the top design speed.

[0032] The longitudinal steps are a structural enhancement that separates the functions of high speed planing from low speed cruising, without resorting to unnecessary spray rails (strakes) or transverse steps. Separating these functions makes it possible to optimize the performance of the central planing surface for high speed planing, independently of the low speed considerations. The factors controlling the separation of these functions determine how this invention is best employed and the optimization realized. This optimization process is for the reduction of drag resistance and takes into account such as weight (displacement) of the boat, the desired top speed, the position of the longitudinal center of buoyancy, the hull width (beam) and other characteristics of the central planing surface. Optimization favors narrower beams in most cases and the use of longitudinal steps makes it feasible to narrow the beam of a central planing surface at one level between pairs of supplemental planing surfaces at a higher level, without constricting the width and accommodations of the overall hull. The separation of the functions in the sequence of events progressing from the at rest to the desired top speed is controlled by the supplemental planing surfaces. The supplemental planing surfaces must provide sufficient lift at an intermediate speed so that the wake and spray from the central planing surface does not wet the supplemental planing surfaces at speeds from this intermediate speed and above until the desired top speed is achieved. With boats having different weights, lengths, beam widths and different ranges in speed, it logically follows that factors influencing the lift described in References 5 and 6 must be considered to employ this invention and determine the optimum central planing surface dimensions to accomplish its lift requirements and the lift of the supplemental planing surfaces to position the central planing surface to carry out its function. Two examples of the separation of the supplemental; planing, central planing surface and separation step (riser) functions have been provided and are described in the Brief Description of Drawings. FIGS. 1 to 8 describe the separation of functions for a relatively medium speed (40 knot) boat with an overall length of 50 feet and weight of 43,000 pounds. The beam (width) of the central planing surface of this boat is 9.0 feet or 60% of the overall boat beam (width) of 15.17. The ratio of the overall boat length to the central planing surface beam is 5.55. A smaller, lighter weight and faster boat will need different dimensions of the central planing surface employing identical concepts as embodied by this patent, The high speed boat, 62.5 knots, with an overall length of 24 feet and a weight of 2780 pounds will need a central planing surface beam (width) is 1.25 feet or 16% of the overall boat width and a ratio of boat length to width of central planing surface of 19.2. In the case of the higher speed smaller boat and its very narrow central planing surface the separation of the functions in the advancement in stages from low speed to high speed may employ more than one pair of supplemental planing surfaces for a total of two or more stages. In the high speed boat example a total of three pair of supplemental planing surfaces and their risers provided the optimum stages of the events to position the central planing surface in control of the overall boat lift. Reducing drag lowers the engine power needs for a given high speed and enables to the use of smaller and lighter engines, thereby reducing the overall weight (displacement). The result is a major saving in engine size, length and desired planing speed. This result is applicable to a wide range of planing power boats from large to small.

[0033] These and other advantages, objects and details of the invention, referred to as, staged longitudinally stepped hull, will become apparent as the following detailed disclosure proceeds.

[0034] A hull moving through the water has three primary components of resistance. The wave making resistance through the water controlled by the shape of the underbody, which for the staged longitudinally stepped hull proposed by this invention consists of a series of hulls stacked on top of each other sharing a common bow and common boat centerline and separated by the vertical height of the steps. Matching a speed range to the narrowest hull form that can support the boat and operate at a range of trim angle from 3.5 to 5 degrees assures the least wave making resistance for each stage over the operating range.

[0035] The second component of the resistance comes from the friction of water against the hull and the wetted surface area. The narrowest hull that will support the weight of the boat at any given stage will present the least wetted surface as long as the spray from that hull, the central planing surface, does come in contact with and wet the supplemental planing surfaces above it. The angle of the hull bottom (deadrise angle) controls the direction of the spray leaving that bottom whereupon its trajectory falls due to the force of gravity. The sharpness of the chine helps the spray to break cleanly and spray strips located along the chine may be employed as dictated by prior art to assist in the clean break. The height of the step is also a factor and included in this patent as a claim. In the separation of the planing functions, each successively widening hull stage, supplemental planing surfaces, must have a bottom (deadrise) angle that is equal to or greater than the bull bottom below it to avoid spray wetting. Claims 5, 7, 9, 14 and 16 all deal with factors to minimize and eliminate a narrower hull from wetting the surfaces above the hull which is in control of a planing stage, except of course during rough water conditions. Adding spray rails or incorporating transverse steps would not alter the primary claims of this invention.

[0036] The present invention is based upon the concept that a wider hull will rise (lift) at lower speeds than a narrow hull opening the possibility of using the lift of a wider hull to raise the hull to position it upon a narrower hull thereby allowing the boat to increase in speed in stages on stacked hulls with the stacks separated by vertical steps and bottom angles set to avoid spray from a narrow stage wetting the surface of the higher wider stage. The stacking enables the use of proven hull forms and a complete hull from transom to bow to enable prediction of the rise (lift), trim angle, dynamic stability and total resistance at any speed as long as the boundary conditions are satisfied. Keeping the trim angle within a 3.5 to 5 degree range assures the combined minimum resistance from both wave making and friction (Ref 5).

[0037] Please refer to the following patents cited by the examiner and relied upon to reject claims 1 through 4:

[0038] It is evident from the prior art that the concept of hull lift and the resulting reduction in wetted surface were appreciated. Patents 4,004,452; 4,022,143; 4,128,072; 4,492,176, 4,453,489; 4,584,959; 4,619,215; 4,726,310; 4,958,585; 5,046,439; 5,063,868; 5,215,025; 5,390,624; 5,443,026 and 5,983,823 provided unique solutions causing the hull to rise resulting in a reduction in resistance by reducing the wetted surface below that of a simple planing hull with a single chine and a smooth hull bottom. All of these patents represent the collective state of the art. None of these patents addressed the issue of spray from a lower surface being directed clearly away from the surface above, the design criteria for assuring a lower surfaces to run dry by sequential (staged) lifting or a design that reduces the total resistance (wave making plus friction) by controlling the trim angle of the complete operating range within the 3.5 to 5 degree optimum range.

[0039] Patent 6,176,196 B1 introduced the concept of a central planing surface with a longitudinal step and discusses the need for a central hull bottom shaped (dead rise angles) to direct spray away from the surface above, but was deficient by not describing the critical range in trim angle required for optimized lift to drag and optimized total resistance, by describing a single step rather than describing the use of multiple stages to optimize the performance over the complete operating spectrum, by restricting the form of the central planing surface as concave, by not relating the height of the vertical step to the rise (lift) of the central planing surface to clear its chine, by describing a concave central planing surface that creates a heavy spray which wets the surface above creating friction, by neglecting the importance of the ideal beam lessons to establish the dimensions of the central planing surface, by suggesting a forward rather than aft of amidship position of the LCB of the central planing surface which tends to reduce the trim angle with a higher risk for dynamic instability (porpoising) and not optimizing the trim angle for least resistance, proposing a central planing surface shape restricting construction to techniques and materials that can be used to form molded shapes, by describing a single longitudinal step rather than multiple steps when the speed range so dictates, by not providing a design where the lift of central planing surface is controlled to assure its chine clears and drys at a speed lower than the hull's design top speed to yield the least resistance at top speed and neglecting the optimization of the wave making component along with the friction (wetted surface drag) component since both contribute toward the objective of reducing power requirements or increasing potential speed with the same power requirement.

BRIEF DESCRIPTION OF DRAWINGS

[0040] For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:

[0041] FIG. 1. Shows a side (profile) view of an exemplary, currently preferred embodiment of a 50′ length overall boat having a monohull embodying the present invention wherein two stages and one vertical step have been incorporated to cover its operating range from 0 to 40 knots.

[0042] FIG. 2 shows a bottom plan view looking upward from beneath the boat shown in FIG. 1.

[0043] FIG. 3 shows a top plan view looking down at the deck of the boat shown in FIG. 1.

[0044] FIG. 4 shows a further, partial, graphical, view of the main cross-sectional cuts through the hull of the boat shown in FIG. 1 at the stations indicated from 0 through 10 drawn below the boat in FIG. 1 with the hull divided in half at its vertical centerline such that the stations from 0 to 5 are to the right of the centerline and stations 6 to 10 are to the left of the centerline and all stations to the port (left) side of the boat observed by a person standing in the boat and facing toward the bow.

[0045] FIGS. 5 to 8 show (in reduced scale) those cross sections referred to in the above description of FIG. 4 which were taken at Stations 2,4,6 and 9 in FIG. 1 for the respective FIGS. 5, 6, 7, and 8 as viewed from the stern.

DESCRIPTION OF THE INVENTION

[0046] As shown in FIG. 4, the exemplary boat hull design of the present invention is compromised of four essential features; (1) One or more inboard chines (one, 46A, in FIG. 4) formed by the intersection of the hull side to the bottom, Chine 44A, (2) A hull bottom with bottom angles from the lower most narrow hull stage(central planing surface) being equal or greater for the hull above (supplemental planing surface) each step as shown in FIG. 4 comparing surfaces 36 to 40, (3) all chines 44 and 46 describe a complete hull tying into a common transom and into a common bow (at different locations) with vertical steps 42 separating the hull bottoms into stages and (4) hull bottom at the keel, essentially (straight) from amidship aft (stations 6 to 10 in FIG. 1) and straight to progressively convex from station 5 to 0 also on FIG. 1.

[0047] At rest the weight of the boat is supported by the buoyancy of the hull underbody at the LWL, 18, on FIG. 4. As the speed is increased from zero the hull sinks slightly causing the LWL is rise slightly. When the speed is further increased, the trim angle increases and a bow wave forms. When the speed in knots is increased to above that associated with the value of the square root of length of the at rest LWL(the distance from 0 to 10 on FIG. 4) times 1.33 to 2.6 the dynamic forces will have lifted the hull back to its at rest LWL or higher. When the hull has risen so that any part of the vertical riser 42A is at or near the Water Line 19, the hull surface above chine 46A will dry and the hull described by chine 46A will control the performance of the boat. Further speed increase will cause the boat to rise further and Chine 46A and its central planing surface will remain in control of the performance of the boat. The designer will calculate (or measure from tests) the rise(lift) necessary to clear the central planing surface Chine 46A and set the number of supplemental planing surface stages so that the trim angle is maintained as close as possible to the optimum range of between 3.5 to 5 degrees, will calculate the rise to set the height of the vertical steps and calculate the ideal beam for the top speed to set the width of the chine 46A of the central planing surface and be guided by the dynamic instability limits for porpoising to assure the entire planing sequence will be stable. This design sequence avoids the excessive trim angles that a wide hull can experience at low speeds by setting the first stage (supplemental planing surface) at a speed below the point where the trim angle rises rapidly while at a speed high enough to cause the boat to rise to the first step.

[0048] It is noted that the embodiments described herein in detail for exemplary purposes are of course subject to many different variations in structure, design, application and methodology. Because many varying and different embodiments may be made within the scope of the inventive concepts herein taught, and because many modifications may be made in the embodiments herein detailed in accordance with the description requirements of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.

Claims

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.