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Title: Boat hull construction
Description: Description:
BACKGROUND OF THE INVENTION Flat bottomed hulls are considered to have good planing characteristics due to the fact that there is a minimum amount of wetted surface and as a result there is a minimum drag as the speed is increased. However, flat bottomed hulls lack stability on turning and also have a tendency to produce a rough ride in choppy water. V-bottom hulls are generally formed with a relative deep V at the bow which flattens out toward the stern. The V-hull has the advantage of being able to cut into heavy seas, although as the V cuts down into the water the water is displaced upwardly along the V and has a tendency to slap against the bottom of the hull. Furthermore, the V-bottom hull lacks lateral stability particularly in the forward areas. More recently the tri-hull has become more popular in smaller boats. The tri-hull consists of a central V along with V's of lesser depth along the side edges of the hull. The tri-hull provides a substantial increase in lateral stability, particularly in the forward areas, but acts to increase the amount of wetted surface so that the planing characteristics of the tri-hull are adversely effected. Various other types of modified V-hulls or tri-hulls have been used in the past in an attempt to obtain better planing characteristics or to increase the stability of the hull. SUMMARY OF THE INVENTION The invention relates to an improved boat hull construction which provides better planing characteristics as well as greater stability. In accordance with the invention, the bottom of the hull is formed with a central longitudinally extending flat surface which extends from the stern toward the bow. The central surface is flat in a lateral or cross sectional direction, through its length. In addition, the bottom is provided with a pair of side surfaces which are parallel to the central surface and are separated from the central surface by upwardly arched channels. Each side surface is flat in a lateral or cross sectional direction throughout its length, and at any cross sectional location, the side surfaces lie in a common plane. The portion of the central surface located adjacent the stern is slightly concave in a longitudinal direction, while the side surfaces are slightly convex in a longitudinal direction. The three parallel surfaces act in a manner similar to water skis and provide improved planing characteristics enabling the boat to plane at substantially lower speeds. In addition, the side surfaces on the bottom of the hull provide excellent lateral stability for the hull, resisting tipping even when a substantial weight is applied to the gunwale. The hull construction also provides improved turning characteristics which minimizes skidding during high speed turns and eliminates the problem of cavitation of the propeller which frequently occurs during high speed skids. Other objects and advantages will appear in the course of the following description. DESCRIPTION OF THE DRAWINGS The drawings illustrate the best mode presently contemplated of carrying out the invention. In the drawings: FIG. 1 is a bottom view of the boat hull construction of the invention; FIG. 2 is a side elevation of the boat hull; FIG. 3 is an end view of the bow of the hull; FIG. 4 is an end view of the stern of the hull; FIG. 5 is a section taken along line 5--5 of FIG. 2; and FIG. 6 is a section taken along line 6--6 of FIG. 2. DESCRIPTION OF THE PREFERRED EMBODIMENT The drawings illustrate a boat hull 1, which can be preferably formed as a hollow shell by molding reinforced plastic material, such as a mixture of a thermosetting resin and glass fibers. In general, the hull is provided with a curved bow 2, and a generally squared off stern 3. Tapered sides 4 and a bottom 5 are connected to the stern and merge into the bow. The drawings illustrate the side surfaces 4 being relatively straight in a fore-and-aft direction, but it is contemplated that the sides 4 can be bowed or convex. In accordance with the invention, the bottom 5 is formed with a central, longitudinally extending surface 6 which extends from the stern toward the bow. The surface 6 is generally flat in a lateral or cross sectional direction, as best illustrated in FIGS. 3-6, and the surface 6 has a substantially constant width from the stern of the boat to a location at the bow. As shown in FIG. 1, the forward portion 7 of surface 6 at the bow is tapered inwardly to provide a lesser width, although the taper is not necessary to the invention. However, it is important that the portion of the surface 6 extending from the stern 3 to the bow 2 have a substantially constant width throughout its length so that it will function in the manner similar to that of a water ski. In addition, to the central surface 6, the bottom 5 is provided with a pair of side surfaces 8 which are parallel to the central surface 6. As in the case of the central surface, the side surfaces 8 are generally flat in a lateral or cross-sectional direction and have a substantially constant width from the stern to a location adjacent the bow. The surface 6 has a substantially greater width than the width of the side surfaces 8. Separating the central surface 6 from the side surfaces 8 are the upwardly arched channels 9. The channels 9 have a greater depth in the area toward the bow as shown in FIG. 3, and have a lesser depth in the area adjacent the stern as shown in FIG. 4. The central surface 6 is bordered by the relatively sharp, parallel side edges 10, and similarly the side surfaces 8 are bordered by the relatively sharp side edges 11 and 12. The channels 9 have a substantially constant lateral width from the stern to the bow and thus a vertical plane passing through the edges 10 is parallel to a vertical plane passing through the edges 11 of the side surfaces. While the central surface 6 is generally flat in a lateral direction, the stern portion of the central surface 6 is provided with a slight concavity in a longitudinal direction, as indicated by 13. On the other hand, the side surfaces 8 are generally convex in a longitudinal direction as best illustrated in FIG. 2. The three flat parallel surfaces 6 and 8 act to combine the best characteristics of a flat bottom full, a V-hull and a tri-hull. The three surfaces 6 and 8 act similar to water skis and minimize the amount of wetted surface, thereby reducing the drag and enabling the boat to plane at substantially lower speeds. In addition, the upwardly arched channels 9 provide a lift effect, which in combination with the flat surfaces 6 and 8, provides the improved planing characteristics. As the hull moves into the water, the surfaces 6 and 8 being flat will displace the water laterally outward from the respective surface in a generally horizontal direction and this water flow along with the air moving through the channels will provide a lifting effect to improve the planing characteristics of the hull. The hull has improved turning capabilities because the relatively sharp edges 10 and 11 will act to dig into the water during a turn and prevent the hull from skidding. Thus, the hull provides a greater number of digging edges during a turn than either the normal V-hull or tri-hull, with the result that the stability is increased and the turning characteristics are improved. The hull construction also has improved lateral stability due to the flat side surfaces 8 which extend from the stern forwardly toward the bow, enabling the hull to resist tipping even when a substantial weight is applied in the gunwale area. This feature also improves the buoyancy of the hull, permitting the hull to carry greater loads. Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention. Other info: Inventors: Bremer, Harry (Elkhart Lake, WI, US) Application Number: 507260 Filing Date: 1974-09-19 Publication_date: 1976-01-06 Assignee: Primary Class(es): 114/61.32 114/290, 114/355, 114/356, 114/357 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Blix, Trygve M. Assistant Examiner: Frankfort, Charles E. Attorney: Andrus, Sceales, Starke & Sawall |
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