Patent Application
20090293790
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Pontoon boats are popular recreational watercraft that are prized for their ability to carry a large number of persons and a heavy load. Pontoon boats were created at least as early as 1952, when a Minnesota farmer, Ambrose Weeres, assembled the first pontoon boat by attaching a wooden deck to the top of two columns of steel barrels welded together end to end to form a cylindrical pontoon. While the preferred metal for the pontoons may now be aluminum, most pontoon boat companies still utilize Mr. Weeres' simple but obsolete design of wooden decks attached to two cylindrical barrel-shaped pontoons, each having a nose cone and an end cap. It is thus an object of the invention to provide a pontoon boat that improves upon the historical design of a wooden deck attached to a cylindrical pontoon.
Historically, the primary means of improving pontoon boat performance consisted of using a larger motor, which provides more thrust, or adding a third pontoon to the center of a pontoon boat, which reduces drag by giving more pontoon surface area to support the weight of the boat and allowing the boat to float higher in the water. The inventors herein have already made advancements in the field of pontoon boats when compared to the historical art. For example, U.S. Pat. No. 7,188,576, issued to the inventors herein, disclosed a method of constructing a pontoon boat from unique interlocking aluminum planks that improved overall boat performance by reducing weight, lowering deck height, and improving rigidity of the overall structure. While these design changes improved pontoon boat performance, such changes did not address the problems that arise from the continued use of traditional cylindrical pontoons. It is desirable for the performance of pontoon boats that the pontoons generate lift. However, cylindrical pontoons of the prior art generate very little lift because the bottom surface of the cylindrical pontoon is rounded. It is thus an object of the invention to provide improved lift qualities to pontoon design.
A pontoon of the prior art typically has at least three components; a nose cone, a number of barrels joined by circumferential welds, and an end cap. The nose cone is typically constructed by forming two nose cone halves, a right and left half. The respective nose cone halves are then welded together along the vertical axis to form the nose cone piece. The position of the weld seam joining the two nose cone halves together presents a possible leakage point because the weld seam runs the length of the nose cone, thereby extending below the water level. Accordingly, the nose cone weld seam is subjected to water and water pressure as the pontoon boat travels through the water. Further, because the nose cone is the most likely location for damage following any sort of collision, such as by running aground, the weld seam is prone to damage and subsequent leakage. It is thus an object of the invention to provide a pontoon with an improved, single-piece nose cone design that does not require a weld seam joining two nose cone halves that is located at the point most likely to suffer predictable damage.
The body of a pontoon is generally constructed from a number of barrel segments. Typically, a pontoon barrel segment is created from a flat rectangular piece of metal that is shaped into a cylinder and joined by a longitudinal weld seam. A typical pontoon is thereafter constructed of two or more pontoon barrels joined at one or more ends using circumferential welds. The barrel-joining circumferential welds are oriented perpendicular to the length of the pontoon, and when the pontoon barrels are welded together, they form a long cylindrical pontoon body to which the nose cone and end caps are attached using circumferential weld seams. Together, when the unit is completed, it is referred to as a pontoon.
Pontoons should be watertight, and although most modern pontoons are filled with foam or other types of floating material to avoid sinking, even slightly leaky pontoons greatly reduce pontoon boat performance due to the relatively high weight of water. Any weld length is a potential source of a leak for a pontoon. For this reason, it is preferred to situate the longitudinal welds above the water surface. With this method of construction, the only welds that routinely come in direct contact with the water are the circumferential welds that join the barrels and the nose cone and end cap to the barrels.
The circumferential weld joining the nose cone to the cylindrical body also presents a potential structural strength problem because the upward force of the water, the forces caused by running the nose cone area aground, are not spread equally across the entire weld; rather, the upward force upon the nose cone tends to compress or stretch various locations of the circumferential weld. It is thus an object of the invention to alleviate the unequal stresses associated with circumferential welds joining the nose cone to the cylindrical body.
In an attempt to improve upon the cylindrical body designs of the prior art and to address poor planing characteristics of pontoon boats in general, in the last decade the pontoon boat industry began welding to the surface of the cylindrical body one or more longitudinal strakes at or below the water surface. As a pontoon boat is typically powered by a rear-mounted engine, the strakes were designed to direct water downward, thus tending to improve the planing characteristics of the traditional cylindrical body by generating lift. Strakes of the prior art represent a rather crude fix to the known problems because most of the running surface of the cylindrical body remained convex.
The limitations to a convex pontoon design can be illustrated by an analogy to treatment of light by a lens: convex lenses scatter light, whereas concave lenses focus light. In pontoons, convex surfaces scatter water pressure away from all sides of the pontoon, whereas concave surfaces directs water pressure downward, thereby generating lift (the direction of force applied by the pontoon upon the water can described by a vector field). It is thus another object of the invention to provide a pontoon design that maximizes lift.
There are clear drawbacks to using after-applied lifting strakes, because if two strakes are used, then at least four longitudinal welds are typically required. Each of the two longitudinal sides of each strake must be attached to the bottom surface of the pontoon. There are many problems associated with welding strakes to existing pontoons, including that each weld increases the susceptibility of leakage in the pontoon in the event a weld is not within acceptable tolerances. This stepwise manner of construction is also time-consuming because it requires a large number of total weld lengths for the pontoon. That is, on a typical pontoon there are longitudinal welds for the creation of the barrel and at least four longitudinal welds for the attachment of two lifting strakes. It is thus another object of the invention to provide a pontoon design that requires a minimal number of longitudinal welds while at the same time adopting the lift and planing advantages offered by strakes.
While pontoon makers have remained relatively traditional in the shape of pontoon hulls, some inventors have experimented with hull shapes in other types of watercraft. However, the problems presented for distinct types of watercraft are markedly different than those faced by pontoon boats, and accordingly the solutions to such problems are likewise different. For instance, U.S. Pat. No. 3,208,421 (the “'421 patent”), issued to W. K. Landes et al., discloses a seaplane float that changes shape from front to rear to reduce drag. The front part of the float has a main concave channel and two smaller concave channels on each side of the main concave channel. The rear portion of the float has two distinct, flat keel pads. In the '421 patent, the inventors used two concave channels. When the seaplane float is viewed from the side, the front of the float tapers into a narrow, aerodynamic trailing edge. The minimal trailing edge of the seaplane float is made possible because the center of gravity of a seaplane is near the front due to the heavy weight of the engine when compared with the lighter weight of the tail of the seaplane. The concerns for a pontoon boat are opposite the concerns facing the inventor for the seaplane float design. The engine on a pontoon boat is in the rear, requiring substantial rear flotation. It is therefore an object of the invention to provide sufficient rear flotation to accommodate engine weight and thrust typical to pontoon boating.
The design of the hull on the seaplane float depicted by Landes defines a separation between three concave channels along the length of the hull. This design allows the seaplane to advantageously ride on the keels alone during high speed takeoff; yet for an aluminum pontoon boat such a design is impractical and undesirable due to the fact that such keel types would impugn the integrity of the concave running surface. It is therefore an object of the invention to provide a fully concave running surface without flat keels to maximize downward force when the pontoon boat is under power.
Sea planes take off and land at relatively high speeds, which require higher curvature of the center concave channel for maximum convergence of water in the twin rear channels to provide lift. It is thus an object of the invention to provide a pontoon that minimizes drag while at the same time providing ample flotation to support an engine mounted at the rear of a pontoon boat.
U.S. Pat. No. 6,293,218 (the “'218 patent”), issued to R. F. White, provides a concave tunnel-hulled boat that utilizes lifting strakes. Like the seaplane float, the tunnel changes shape from fore to aft; also, the leading edge of the tunnel is formed from two concave channels which tapers to one concave channel as the tunnel progresses rearward. The objective of the concave tunnel for which the '218 patent was to mount a motor higher on the transom of the boat, thus providing a shallow draft and minimizing propeller damage in shallow waters. This tunnel-hulled boat requires the additional use of sponsons to replace the buoyancy necessarily lost by implementing a tunnel into the tunnel-hulled boat. The '218 patent further requires relatively flat surfaces for the remainder of the hull of the boat such that the concave tunnel is merely one component of the overall hull design. It is thus an object of the invention to provide a sufficiently buoyant pontoon for which the entire running surface is generally concave, rather than merely having a localized concave tunnel as a feature of an otherwise rounded or flat pontoon.
U.S. Pat. No. 6,067,923 (the “'923 patent”), issued to Ratcliff, provides a hull configuration for a catamaran boat. The design of such hull is divided such that the forward two-thirds of each hull is V-shaped, which such V-shape being very pronounced at the front of the keel. Like the seaplane and the tunnel-hulled boat discussed above, the catamaran's hull tapers toward the rear, and the rear of the hull has a flat keel pad and flat lifting strake pads separated by ridges. Each ridge in the catamaran hull requires three distinct points at which the surface abruptly changes; these three angles adversely affect performance because the flow of water from the sharply angled ridge moves toward a different point than water moving over the flat keel, which generates turbulence. It is thus an object of the invention to provide a smoothly curved running surface which provides more lift for pontoon boats. It is thus an object of the invention to provide a large, smoothly curved, concave running surface for a pontoon such that the transition between running surface and lifting strake requires a minimum number of sharp angles.
The apparatus in accordance with the invention provides a concave pontoon that provides improved pontoon boat performance by maximizing lift and minimizing leakage by reducing weld length exposed to the water. The invention also provides reduced construction costs because it lowers the number of welds required to form a pontoon with lifting strakes.
An apparatus and associated method for producing an improved pontoon is provided. The pontoon comprises a concave main running surface having a centerline that is perpendicular to the surface of the water, the main running surface being bounded by two sponsons, which in turn are bounded by two distal concave surfaces, or integrated lifting strakes. Thus, the invention provides at least three surfaces that direct water substantially downwardly perpendicular to the surface of the water, which provides maximum lift. The associated method of construction of this improved pontoon design has five preferred embodiments.
The first preferred embodiment for construction of the improved running surface and integrated lifting strake is formed as one main longitudinal insert. Each of the two longitudinal edges of the insert offer a receiving flange along the entire length of the insert. In order to construct the remainder of the cylindrical body, a single sheet of material, preferably aluminum or an alloy thereof, is cut to a length that corresponds to the insert and is shaped into a semi-circular barrel. The longitudinal edges of the cylindrical body are inserted into the receiving flange and thereafter joined with a welded seam. A nose cone and a rear cap are joined to complete construction of the pontoon. This first preferred embodiment has an additional advantage in that it is capable of being retrofitted to pontoons of the prior art.
In the second preferred embodiment the entire length of a pontoon body, with the exception of the nose cone and end cap, is constructed using one relatively flat, rectangular piece of material, preferably aluminum or an alloy thereof. The improved running surface and integrated lifting strakes are formed using a metal press along the longitudinal centerline of the material, and the two substantially equal amounts of flat material remaining are then shaped to form the remainder of the cylindrical body of the pontoon. The material is thereafter joined into the cylindrical shape with a welded seam. Such welded seam is preferably located along the top longitudinal edge of the pontoon cylinder. A nose cone is thereafter joined onto the front portion of the pontoon cylinder, and a rear cap is also joined, thus completing construction. This design requires only one longitudinal seam to form the pontoon cylinder, one seam joining the nose cone to such cylindrical body, and one seam joining the end cap to the cylindrical body. The longitudinal weld is located on the top surface of the pontoon and out of the water.
In the third preferred embodiment the entire length of a pontoon cylinder is also constructed from one relatively flat, rectangular piece of material, preferably aluminum or an alloy thereof. The preferred running surface with integrated lifting strake is formed offset to one side of the starting material. As part of the forming process, a flange may be incorporated into the design to receive the corresponding material edge, thereafter joined by welded seam. A nose cone is thereafter joined onto the front portion of the pontoon cylinder, and a rear cap is also joined, completing construction. This design requires only one longitudinal seam to form the pontoon cylinder, one circumferential weld seam joining the nose cone to such cylinder, and one circumferential weld seam joining the end cap to the cylinder.
In the fourth preferred embodiment the entire length of the pontoon cylinder is constructed from a single sheet of relatively flat material, preferably aluminum or an alloy thereof. Like the second preferred embodiment, the improved running surface with the integrated lifting strake is formed along the longitudinal centerline of the material. However, in the fourth preferred embodiment, the remaining portions of the material adjacent to the improved running surface are shaped substantially perpendicular to the running surface. The pontoon cylinder is thereafter welded to the bottom of a metal deck, thereby securing the entire length of the pontoon cylinder directly to the deck. The longitudinal edges of the pontoon cylinder may be flanged to facilitate a strong attachment between the pontoon cylinder and the deck. This design eliminates the need for extra material (and weight) required by the top of a pontoon and by mounting brackets used to attach the deck to the pontoon. When used in a method of construction with the modular interlocking deck that is the subject of another patent by the inventors, the third preferred embodiment obviates the need for additional structural reinforcement. Depending on the final desired shape of the sides, a strengthening strut or internal baffles may be added. A nose cone is applied to the front and a rear cap is joined to the rear to seal the pontoon cylinder, which completes construction. This design requires only two longitudinal seams formed between the deck and the pontoon cylinder, neither of which will be exposed to water, and has the further advantage of obviating the need for mounting brackets and adding structural integrity and stiffness to the overall pontoon boat.
In the fifth preferred embodiment the entire length of a pontoon is constructed from one relatively flat, rectangular piece of material, preferably aluminum or an alloy thereof. At the end designed to serve as the nose of the pontoon cylinder, a W-shaped tab is removed from the relevant center portion of the transverse side of the metal sheet. The improved running surface with the integrated lifting strake is thereafter formed along the longitudinal centerline of the metal. The two remaining unformed sides are thereafter shaped until the longitudinal edges of the material abut one another and are joined with a longitudinal welded seam. When the cylindrical body is formed from the solitary piece of metal cut in this fashion, the W-shaped tab forms a substantially flat angled surface to which a one-piece front cap may be welded. The one-piece front cap may be substantially flat or it may have some curvature. In this fifth preferred embodiment, because the one-piece front cap is not constructed of two halves, the force of the water may be spread evenly over the welds securing the one-piece nose cap, and the one-piece nose cap works in conjunction with the integrated lifting strake to provide even more lift than the pontoon with integrated lifting strake alone.
Each preferred embodiment is useful in pontoon boats with two or more pontoons. Each preferred embodiment can also be constructed using more traditional methods, such as creating the pontoon using multiple barrels, each having the improved running surface incorporated therein, and then welding the barrels together. Further, each of the embodiments contemplates that the location of the improved running surface and lifting strake can be formed into an arbitrary longitudinal location on the material (i.e., not the center or one side of the material), if desired, to change the locations of the seams with respect to the running surface.
These and other advantages provided by the invention will become apparent from the following detailed description which, when viewed in light of the accompanying drawings, disclose the embodiments of the invention.
The invention as disclosed herein provides a pontoon with an improved running surface. The improved running surface comprises a concave main running surface having a centerline that is perpendicular to the surface of the water, further bounded by two sponsons, which in turn are bounded by two distal concave surfaces, or integrated lifting strakes. Thus, the invention provides at least three surfaces that direct water substantially downwardly perpendicular to the surface of the water, which provides maximum lift. The invention also includes several methods of manufacturing the pontoon, with the goal of such methods being to minimize the number of welds required in the manufacturing process, avoiding the number of welds exposed to water, and providing higher quality control by using automated manufacturing systems.
Referring now to the drawings,
Referring now to
In prior art manufacturing techniques, a nose cone 117 is joined to pontoon 105 via nose cone circumferential weld seam 119, as well as a rear end cap 121 that is joined to pontoon 105 via rear end cap circumferential weld seam 123. Nose cone 117 (shown in
Referring now to
Nose 143 may be a nose cone 117 of the prior art but is separately named to illustrate the differences between the nose cone 117 of the prior art with the advancements made by virtue of the manufacturing processes disclosed herein. Preferably, as shown in
Similarly, end 145 may be a rear end cap 121 of the prior art but is separately named to illustrate the differences between the methods disclosed herein and the prior art. Preferably, as shown in
The accompanying drawings show obtuse sponson angle 151 as equal on both transverse sides of PILS 133 and acute lifting strake angle 161 as equal on both transverse sides of PILS While such a configuration may be preferable in some situations, such as where PILS 133 is installed along the longitudinal centerline of a pontoon boat, the inventors intend no such limitation on the apparatus disclosed herein or the associated methods. Rather, the inventors contemplate that obtuse sponson angle 151 may be different on the two transverse sides of PILS 133, and acute lifting strake angle 161 likewise may be different on the two transverse sides of PILS 133. For example, obtuse sponson angle 151 may be less obtuse, and acute lifting strake angle 161 may be more acute, on the transverse side of PILS 133 proximal to the longitudinal centerline of a pontoon boat, which deepens the concavity of improved running surface 135 proximal to the longitudinal centerline of the pontoon boat. Conversely, obtuse sponson angle 151 may be more obtuse, and acute lifting strake angle less acute, on the transverse side of PILS 133 distal to the longitudinal centerline of the pontoon boat, which shallows the concavity of improved running surface 135 distal to the longitudinal centerline of the pontoon boat. Deeper concavity of the improved running surface 135 proximal to the longitudinal centerline of a pontoon boat, taken alone or in conjunction with shallower concavity of the improved running surface 135 distal to the longitudinal centerline of a pontoon boat, assists with cornering and stability of a pontoon boat by forcing the boat to plane primarily on the improved running surface 135 and integrated lifting strake 139 distal to the centerline of the pontoon boat.
PILS 133 provides a number of advantages over the prior art. When a pontoon outfitted with PILS 133 is in the water, PILS 133 resembles a prior art pontoon 105. However, PILS 133 provides improved performance and better fuel economy because when under power PILS 133 planes on top of the water by forcing water downward, rather than pushing water to the side like prior art pontoon 105. Further, PILS 133 assists with trailering, as improved running surface 135 provides a convenient location for communicating with the cradle of a boat trailer.
Persons having ordinary skill in the art will recognize that PILS 133 may be formed from metal according to the methods presented below, may be cast from molded fiberglass, may be constructed of wood or other traditional materials, or may be made using other materials and methods suitable for marine use.
The method associated with PILS 133 has five preferred embodiments. Referring now to
The first preferred embodiment has the added benefit of allowing the invention to be retrofitted to pontoons 105 of the prior art. In order to do so, nose cone 117 and rear end cap 121 of pontoon 105 are removed. Then, a rectangular piece is longitudinally removed (not shown) from the bottom of pontoon 105 to form flotation cavity walls 141 as shown in
Turning now to
The second preferred embodiment has numerous advantages over the prior art. The second preferred embodiment provides PILS 133 that requires only one longitudinal weld, whereas prior art pontoons 105 with longitudinal strakes 111 required one longitudinal weld for the pontoon 105 and four additional longitudinal strake welds 113 for longitudinal strakes 111, for a total of not less than five longitudinal welds. Fewer welds provides fewer potential failure points on PILS 133 than prior art pontoons 105. Further, the second preferred embodiment has no welds below the waterline, while prior art pontoon 105 has at least two longitudinal strake welds 113 below the waterline when pontoon boat 101 is on plane and at least four longitudinal strake welds 113 below the waterline when pontoon boat 101 is not on plane.
Turning now to
Turning now to
While the fourth preferred embodiment shows each flotation cavity wall 141 as substantially perpendicular to deck 179, the inventors contemplate that the wall may be curved or shaped otherwise as necessary to provide appropriate pontoon boat flotation and performance; the utility of the fourth preferred embodiment lies primarily in the attachment of PILS 133 directly to deck 179.
The fourth preferred embodiment provides many advantages over the prior art. For instance, the fourth preferred embodiment eliminates mounting braces 107 between prior art pontoons 105 and deck 103. Not only does this represent a weight savings that allows better overall boat performance, it also lowers the center of gravity of the pontoon boat, which provides better stability in rough seas. Furthermore, by combining the fourth preferred embodiment with a pontoon boat deck such as the one disclosed in commonly-owned U.S. Pat. No. 7,188,576, several steps in the construction of the pontoon boat are consolidated, thus reducing manufacturing times and costs.
Turning now to
As shown in the fifth preferred embodiment, nose cap 181 is substantially planar. Optionally, nose cap 181 may be formed into arbitrary non-planar shapes, such as, for example, a V-shape formed with a bend at the longitudinal centerline of nose cap 181. In order for transverse edge 173 to receive non-planar nose cap 181, tab 183 must be modified accordingly. For instance, a V-shaped nose cap 181 would require a substantially U-shaped tab 183, as opposed to a W-shaped tab 183 for planar nose cap 181. A V-shape nose cap 181 allows PILS 133 to closely resemble prior art pontoon 105 while retaining the same manufacturing advantages provided by the fifth preferred embodiment.
The fifth preferred embodiment addresses a deficiency in the design of prior art pontoons by spreading the force of oncoming water over the welds securing one-piece nose cap 181. That is, water pressure 185 applies force to nose cap 181 in a direction perpendicular to the seam between nose cap 181 and transverse edge 173. Therefore, the force applied to nose cap 181 is spread substantially evenly over nose cap 181 and the seam between nose cap 181 and transverse edge 173. Furthermore, the fifth preferred embodiment provides an advantage of the prior art in that nose caps 183 are easier to manufacture and install than nose cones 117 because nose caps 183 are made of one piece, rather than two nose cone halves 125 that must be welded together. Assembly is also easier with nose caps 183 because PILS 133 is preferably installed to deck 179 upside down; that is, the bottom of deck 179 faces upward, and the top part PILS 133 rests on deck 179 during assembly. Thus, the angle of transverse edge 173 at the bow of PILS 133 faces upward, and nose cap 181 can rest on transverse edge 173 with minimal securing means during assembly.
Persons having ordinary skill in the art will recognize that edges may be formed in sheet 169 using a press brake or other similar machine. Curves may be formed in sheet 169 by use of a plate roll or other similar machine. Curves are typically formed into sheet 169 prior to edges being formed, as a plate roll is easier to operate when no edges interfere with the sheet feeding mechanism of the plate roll. Thus, in preferred embodiments two through five, flotation cavity wall 141 on one transverse side of sheet 169 is typically curved first, followed by improved running surface 135, then by flotation cavity wall on the opposite transverse side of sheet 169. Sheet 169 is then fed into a press brake, which is used to form sponsons 147, proximal lifting strake edges 153, and distal lifting strake edges 157. Of course, persons skilled in the art will also recognize that curved surfaces can be replaced with other geometric shapes so that the only equipment necessary to manufacture the pontoon with integrated lifting strake is a press brake. For instance, five sides of a regular hexagon or seven sides of a regular nonagon could serve as flotation cavity wall 141.
While the inventors have described above what they believe to be the preferred embodiments of the invention, persons having ordinary skill in the art will recognize that other and additional changes may be made in conformance with the spirit of the invention and the inventors intend to claim all such changes as may fall within the scope of the invention.
