|Publication number||US3160897 A|
|Publication date||Dec 15, 1964|
|Filing date||Apr 15, 1963|
|Priority date||Apr 15, 1963|
|Publication number||US 3160897 A, US 3160897A, US-A-3160897, US3160897 A, US3160897A|
|Inventors||Kelly Jr John M|
|Original Assignee||Kelly Jr John M|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (2), Referenced by (13), Classifications (6)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Dec. 15, 1964 KELLY, JR 3,160,897
HYDROPLANE SURFBOARD Filed April 15, 1963 2 Sheets-Sheet l INVENTOR. JOHN M. Kim; J/Q
M wiw 1366- 1964 J. M. KELLY, JR
HYDROPLANE SURFBOARD 2 Sheets-Sheet 2 Filed April 15, 1963 JOHN M. AFLD, we
A 7'70/P/V5KSY United States Patent" 3,169,397 HYDRGPLANE SURFEGARD John M. Kelly, In, 4117 Black Point Road, Honolulu, Hawaii Filed Apr. 15, 1953, Ser. No. 273,924 4 Claims. (Cl. 9-310) This invention relates to a surfboard.
Most surfboards now in use are made with curved 1ongitudinal profiles which rock about their centers of gravity in a manner to aid the rider in maintaining his fore-andaft balance and to allow the board to approximate the curvature of the forward slope of the wave. The major disadvantage in such a rocker construction is that the board drags a quantity of water when moving directionally over and through the water thereby inhibiting its speed which limitation cannot be overcome by the rider. While drag may be desirable when the rider wishes to stall and thus ascend to a higher position on the wave, he
also needs maximum speed capability to shoot the curl,
i.e. to plane across the face of the wave, perhaps the most desirable riding maneuver. may need to stall again or to turn at high speed to avoid hitting another rider, to avoid rocks or to navigate wind chops or unevenness on the waves slope.
Other surfboards now designed for use exclusively in big surf, i.e., for waves above feet in height, are constructed to maximize speed by minimizing the rocker curvature and providing sharp breakaway edges around the stern. However, because of their elongated, straight and relatively flat tails which are adverse to the curved path of the surfboard when engaged in turning, these boards are inherently incapable of maneuvering at high or at low speeds. Thus, these boardssacrifice maneuverability to achieve high speeds whereas the aforementioned rocker boards sacrifice speed for maneuverability.
The primary object of .the invention is to overcome the aforementioned disadvantages resident in the conventional surfboards by combining in a single surfboard acces- ,sibility of both extremely high as well as low speeds and increased maneuverability at all speeds- This combination of heightened functions is accomplished by providing a planing surface and a scorpion tail which are physically differentiated by a transverse shoulder so that the rider, by body movement or shift in weight, can bring the planing surface into partial or full play or bring the drag into effect thereby achieving a wide range of speeds while maintaining maneuverability throughout.
Another object of the invention is to provide a surfboard which readily enables the rider to attain a wide range of ,speeds as well as accentuated maneuverability at all speeds by the functional coaction between a number of features which comprise a planing surface and a scorpion tail which are differentiated physically by a transverse shoulder thereby creating discretely separated bottom surfaces,
At any moment, the rider the tail curving upwardly above the wake and tapering.
towards its tip away from the shoulder to provide a cutaway at the sides of the board in the location of the tail. The cutaway, taking advantage of the clean partition of the water from the board at the sharp breakaway edge of the transverse indentation at the bottom and sides, acts 'as a means to prevent the water from being sucked in U around the stern and create a drag from which the rider i cannot release himself. The same is true for the lift of the tail. I V v Another object of the invention is to provide a surfboard which enables the rider to attain a wide range of speeds, a. greater maximum speed, and accentuated maneuverability, yet the board'is relatively simple in design construction and easier to operate than other models.
These and other objects and features of the lnvention 1 will become more apparent as the following description proceeds in conjunction with the accompanying drawings, wherein:
PEG. 1 is a side elevational view of the surfboard;
FIG. 2 is a bottom plan View thereof;
FIGS. 3, 4 and 5 are fragmentary elevational views of modified forms of shoulders;
FIG. 6 is a fragmentary bottomplan view of modified forms of a board at the aft end of the planing surface and scorpion tail;
FIGS. 7, 8 and 9 are fragmentary enlarged views of the tail end of the surfboard illustrating respectively low, partial and maximum drag;
FIG. 10 is a fragmentary vertical sectional view through the board just aft of and looking at the shoulder and illustrating one type of side edge at the planing surface; and
FIG. 11 is a view similar to FIG. 10 illustrating another type of side edge at the planing surface.
Specific reference is now made to the drawings wherein similar reference characters are used for corresponding elments throughout.
The surfboard of the instant'invention is generally indicated at 10 and is an elongated member capable of being fabricated of a wide variety of materials, preferably fiberglass-covered air-expanded plastic foam or balsam wood. The rider engages the upper or deck face 12 while the opposite or bottom face 14 is adapted to engage the water. The how 16 is tapered and preferably upwardly curved to provide a scoop, whereas the stern includes an upwardly curved scorpion tail 18 having a bottom or tail surface 22.
The bottom face 14 includes two separate and distinct surfaces, one the tail surface 22 and the other a planing .surface 24 forward thereof having a skeg 24 depending from its after end. 7 These surfaces are differentiated by providing a transverse shoulder 26 formed in the bottom face which consists of a break in the lines of the side and bottom profiles in such a manner that the tail surface 22 is elevated above the planingsurface 24. The maximum depth of the shoulder, i.e.-the distance bywhich the tail surface 22 and the planing surface 24 are separated, may vary from one-eighth to'four inches depending .upon the body weight and preferences of the riders as to height of the waves to be ridden, the degree of slope of the waves at which the higher speeds are desired and the degree of braking effect desired, the depth of maximum efficiency proceeds aft curving inwardly from both sides to meet at a point varying from approximately two inches from the stern to a point midway between the bow andstern depending upon the overall length of the-board and the preferences -of the rider as to maximum speed desired,
degree of braking effect and sharpness of turning ability, the location for average desired capabilities being ap proximately six to eighteen inches from the stern for surfboards averaging eightto twelve feet in overall length,
saidshoulderdeepening as it curves upwardlyin the rearward direction to its maximum depth. As. shown in solid lines in FIG. 6, an alternative construction is one in which the shoulder 26 may be convexly curved towards .the tail as at 25 but cutoff at its apex along'a line 27 transverse to the longitudinal axis ofthe surfboard. The tailmay be correspondingly convexly tapered and facture, as well as to reduce danger of too sharp a breakaway edge, the same may be rounded to a radius of curvature of approximately one-quarter of an inch. It should belunderstood, however, that a sharper breakaway edge is functionally preferable due to hydrodynamic action of fluids in separating from plane surfaces. The shape of the shoulder as viewed from .the. side may vary from a deep recess or acute angle 39 as shown in FIGURES 1, 2, 3 and 7-9 through a substantially right angular recess 32 as shown in FIGURE to a shallow recess 34 somewhat iii-excess of ninety degrees as shown in FIGURE 4. V Z a The planing surface 24 functions at maximum efliciency when it is fiat, both transversely and longitudinally, al-
though it may be curvedboth longitudinally and trans-,
Versely, the degree of longitudinal curvature being least at the shoulder and greatest where the planing surface and bow scoop merge as at 36, see FIG. 1. The side edges of the planing surface may be rounded as, shown at in FIG. 11 'to causethe board to groove slightly into the wave but for maximum etiiciency they fair down gently from the deck at an angle of approximately fortyfive degrees to end in sharp side breakaway edges as shown at 42in FIG. 10; The radius of curvature of each side edge from the shoulder forward a distance approximately equal to the length of the planing sur-. face, for maximum efiiciency, should not exceed onethirty-secondth of an inch, the edge becoming rounded Iii.
greater speed. In either case of indentation or absence thereof, the scorpion tail should lie within and not ex- .ceed the dimension across the wake area as produced by the shoulder, the planing surface and the maximum .Wldth of the surfboard forward of the shoulder.
The edges of the scorpion tail are so curved that tail surface 22 fairs gradually upward to meet the deck surface 12 in a high-drag breakaway edge comprising the periphery of tail 18 the radius of curvature being not iess than one-eighth of an inch at the edge itself but with maximum drag effect being achieved with a curvature of approximately one and one-half to two inches radius.
The skeg 2%) should be long enough to extend from approximately two to twelve inches below the line extending aft of chaplaning surface 24 with maximum efiiciency being achievable for turning at all speeds when the skeg is located at the aft end of the planing surface.
In use, the rider stands on the deck of the board and by leaning his weight on the forward foot he brings the planing surface 24 into partial play and by taking a stance farther forward brings it into full play. By leaning back on the foot placed to the rear, he minimizes planing and brings the drag into effect. FIG. 7 shows the condition of thewater '44 at low drag yielding high speed, FIG. 8 shows the condition at partial drag yielding intermediate speed and FIG. 9 shows the a condition at maximum drag yielding slow speed. The
as it merges with the rounded sides of the board at the a bow end. r v
The dimensions of the planing'surface 24 may vary according to the overall dimensions of the board and height, weight, and individual preferences of: the rider,
said planing surface comprising that-longitudinallyv fiat area situated between thejuncture 28 of shoulder 26 with planing surface 24 and the area of the commencement of the bow scoop' 36, but in the event of the curvature of the scoop extendingaft to' the juncture 28, the
planing surface constitutes the wetted portion of the undersurface in riding .position, excluding the scorpion tail, which varies in length, width and area as to the weight of the rider and trim and speed in riding posi-' tion on the wave. The instant board can have a straight instead of an uplifted bow, in which case the planing surface extends from the shoulder forward to the bow extremity of the board thereby comprisinga major portion of the total bottom surface.
The entire section aft of the shoulder 26 is the scorpion tail 18 which is elevated above the planing surface in the manner indicated hereinbefore with reference to the depth of the shoulder. The: scorpion tail is curved both longitudinally and transversely and upwardly from the.
plane of the planing surface, the upward curvature varying from slightly abovethe plane to a maximum of approximately eight inches measured from the tip-10f the tail to the extension of the; plane aft of the shoulder.
It will be seen from'FIG. 2 that the sides of the scorpion tail curve inwardly or taper in diminishing width from the shoulder to the tip: of the tail to provide a cutaway 38, which is the space between the extensions 5' aft of the sides of the board beyond the'shoulder and the sides of the tail as seen in FIG. 2. .The sides of the scorpion tail at the shoulder may be sharplyindented scorpion tail provides a. curvature adapted to the shape of the turning circle when depressed into the water thus enabling the rider to attain superior turning capability. The cutaway 33 at the tail enables the water to part cleanly from the sides of the board rather than be sucked in around the stem at all times, as on conventional boards, thereby creating drag from which the rider cannot release himself. Thus, with the instant surfboard, the rider'can-achieve any degree of speed while maintaining maneuverability throughout.
This application is a continuation-in-part of my copending application Serial No. 226,045 filed September 25, 1962, now Patent No. 3,111,695.
I claim: 7
l. A surfboard comprising an elongated member having a deck and a bottom face, and a vertically and transversely extending shoulder in the bottom face dividing said face into two discreet vertically spaced surfaces, the
of said shoulder, and a skeg depending from the after end of said planing surface the normal stance of the rider for planing being with one foot over the skeg and the other foot forwardly thereof over the planing surface.
2 A surfboard comprising an elongated member having a deck and a bottom face, "and a'vertically and transverselyextending shoulder in the bottom face, dividing said face into two discreet vertically spaced surfaces, the
upperone extendingaft of the shoulder to the stern and constituting a tail surface and the lowerone extending L forwardly of the shoulder and constituting a planingsurface, theportion of theboard aft of said shoulder being a scorpionstail whose sides taper inwardly towards the stern to provide a cutaway-portion between the sides of the tail and extensions of theaside s of the board aft of said shoulder, said. shoulder being convexly curved toward the tail. 1 r
' 3. A' surfboard comprising an elongated member having a deck and a bottom face, and a vertically and transby acute angles or by right angles or may also be continuous with the curvature of the sides of theboard, though the aforementioned indentation affords less dragand f/er'sely extending shoulder 'il'lfi'hfi bottom face dividing said face into two discreet vertically spaced surfaces, the upper one extending aft of the shoulderto the. stern and constituting a tail surface and the lower one extending forwardly of the shoulder and constituting a planing surface, the portion of the board aft of said shoulder being a scorpion tail whose sides taper inwardly towards the stern to provide a cutaway portion between the sides of the tail and extensions of the sides of the board aft of said shoulder, said planing surface being transversely curved, said shoulder being convexly curved toward the tail and a skeg depending from the after end of said planing surface.
4. A surfboard comprising an elongated member having a deck and a bottom face, and a vertically and transversely extending shoulder in the bottom face dividing said face into two discreet vertically spaced surfaces, the upper one extending aft of the shoulder to the stern and constituting a tail surface and the lower one extending forwardly of the shoulder and constituting a planing surface, the portion of the board aft of said shoulder being a scorpion tail whose sides taper inwardly towards the stern to provide a cutaway portion between the sides of the tail and extensions of the sides of the board aft of said shoulder, said shoulder being convexly curved toward the tail, and a skeg depending from the after end of said planing surface.
Eicholtz Feb. 14, 1961 Kelly Nov. 26, 1963
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|U.S. Classification||441/74, D21/769|
|International Classification||B63B35/79, B63B35/73|