FIELD OF THE INVENTION The present invention relates to surfboards.

BACKGROUND OF THE INVENTION

Conventional surfboards, used for riding waves, are formed of an elongated buoyant board having a smooth surface with a pointed bow and a generally straight transverse stern. The sportsman is forwardly propelled by the breaking waves while standing up or lying on his chest on the board.

It has been found by the inventors that the directional stability and the propelling efficiency of the conventional surfboards could be improved. OBJECTS OF THE INVENTION

It is therefore the general object of the present invention to provide a surfboard having improved propelling efficiency and also improved directional stability.

Another object of the present invention is the provision of a surfboard having a plurality of transverse ridges formed by grooves in its bottom surface to increase the surfboard faces exposed to the forwardly moving water, and said ridges being arcuate and bowed away from the front end of the surfboard to provide directional stability. A further object of the invention is to provide a pair of additional sets of ridges on the opposite lateral side surfaces of the board, to improve self-straightening of the board in motion upon the board accidentally swerving out of its main axial direction of displacement. Another object of the present invention is to provide a surfboard having these improved characteristics and which is yet of simple and inexpensive construction.

SUMMARY OF THE INVENTION The surfboard of the present invention has an elongated buoyant body having top and bottom surfaces, a front and a rear end and including a set of arcuate

transverse ridges formed by grooves in said bottom surface, the ridges bowed away from said front end, being symmetrical relative to the longitudinal axis of the surfboard and spaced from one another longitudinally of the body.

Each ridge has an exposed edge face forming part of the bottom surface of the surfboard and, preferably at least some of the ridges are formed with a channel extending across the edge face, all of the channels being aligned along the longitudinal axis of the body.

Preferably, each channel flares at its front end.

Preferably, each groove is defined by the front face of any given ridge and by the back face of an adjacent preceding ridge, each groove of V-shaped cross-section and said front and back faces being upwardly and frontwardly inclined. Preferably, the apices of the several grooves are substantially equally downwardly spaced from the top surface of the body. The ridges include a rearmost ridge, a frontmost ridge and intervening ridges. The rearmost ridge has a rear surface which forms the stern of the surfboard body and which is substantially convex with a profile substantially normal with the bottom surface adjacent the latter and of increasing inclination while approaching said top surface. The frontmost ridge has a front surface which forms the bow surface of the surfboard body, said bow surface being convex in planes normal to and parallel to said top and bottom surfaces.

The surfboard has straight sides which form longitudinally extending side ridges each having an edge face which merges with the edge faces of transverse ridges.

A second and a third set of arcuate transverse ridges may further be formed by grooves made in said one and another side surfaces respectively, said ridges of the second and third set including a frontmost ridge, a rear ridge and at least one intervening ridge, all of said ridges bowed away from said front end, and spaced one from

the other longitudinally of said body, said ridges of the second and third set having an exposed edge face forming part of said one and another lateral side surfaces respectively, said frontmost ridges of the second and third set of ridges arcuately converging toward one another but extending short of said longitudinal ridges merging at the front end of the surfboard body.

Preferably then, each groove of said intervening ridges is defined by the front face of one said ridges and by the back face of one said intervening ridges, each groove being of V-shape cross-section; a groove further rearwardly depending from said rearmost ridges of each of the first mentioned set, second and third sets of arcuate transverse ridges, wherein three coextensive groove mouths are defined at the rear end of the surfboard body.

DESCRIPTION OF THE DRAWINGS

In the annexed drawings:

Figure 1 is perspective view of the deck of a first embodiment of surfboard according to the invention;

Figure 2 is top plan view of the surfboard of fig 1;

Figure 3 is a bottom perspective view of the surfboard of fig 1;

Figure 4 is a bottom plan view of the first embodiment of surfboard, with the arrows suggesting the waterflow through the underface grooves;

Figures 5 and 6 are enlarged longitudinal sections taken along V-V of figure 2 and VI-VI of figure 4 respectively;

Figure 7 is a perspective view of the deck of an alternate embodiment of surfboard;

Figures 8 and 9 are an edge view and an top plan view respectively of the embodiment of figure 7;

Figure 10 is a bottom plan view of the surfboard of fig 7;

Figure 11 is a perspective view of the hull of the surfboard of figure 7; and

Figure 12 is a cross-sectional view at a slightly enlarged

scale, taken along line XII-XII of figure 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the first embodiment of surfboard of the invention illustrated in figures 1-6 of the drawings, there is provided an elongated body 2 made of buoyant material such as foam plastic, preferably covered with a skin of a rigid and impervious plastic material. The surfboard body 2 has a generally flat and smooth top surface 4 and a generally flat bottom surface 6 and is terminated by a front or bow end 8 and a rear or stern end 10.

The bottom surface 6 of the surfboard body 2 is provided by grooves which form a frontmost ridge 12, a rearmost ridge 14, intervening ridges 16 and longitudinal sides ridges 18. Ridges 12, 14 and 16 extend transversely of body 2 while ridges 18 extend longitudinally of body 2.

Side ridges 18 have side faces 20 and frontmost ridge 12 defines a bow surface 22 which is convex in planes normal and parallel to surfaces 4 and 6. The rearmost ridge 14 defines a stern surface 24 with a convex profile normal to said bottom surface 6, adjacent the latter and of increasing inclination while approaching the top surface 4.

All of the ridges 12, 14 and 16 are bowed away from front end 8.

Ridges 14 and 16 have a front face 26 while ridges 12 and 16 have a back face 28. Faces 26 and 28 are the sides of the above-mentioned grooves which each is V- shaped and has an apex 30. Preferably, front faces 26 have a convex profile while back face 28 has a concave profile. Both faces are upwardly, forwardly inclined with respect to body 2. The exposed edge faces of ridges 12 to 18 collectively form bottom surface 6.

A central channel 32 is formed across each intervening ridge 16. Each channel 32 has a front flaring end 34. These several channels are in alignment with the longitudinal axis of the surfboard body 2.

A holding rope 36 is provided with a collar 38 at

its outer end while its inner end is attached to a rope anchor 40 secured to the bow of body 2 centrally thereof.

The provision of the intervening ridges 16 and frontmost ridge 12 considerably increases the surface of the surfboard which is exposed to the incoming water flow, as compared to a conventional surfboard, in which only the stern surface 24 is so exposed. The rushing water enters the successive V-shaped grooves and impinges the back surfaces 28 and against the apices 30 causing not only forward movement of the surfboard through the water body but also a certain lifting effect on the surfboard in the water body.

The axial channels 32 enable the water to flow forwardly from one groove to the other in order to more uniformly distribute the forces exerted by the oncoming water on the surfboard body 2.

The transversely arcuate or bowed shape of the intervening ridges 24 and also of front ridge 12 deflects the oncoming water laterally inwardly towards the centre of the surfboard from each side thereof insuring directional stability of the surfboard.

In the alternate embodiment of the surfboard illustrated in figures 7 to 12, corresponding elements relative to the first embodiment will be bear the same numerals but into a 100 series. Accordingly, this alternate embodiment of surfboard consists of an elongated body 102 made of buoyant material still having a generally flat and smooth top surface 104 and a generally flat but somewhat slightly convex bottom surface 106, and is terminated by a front or bow end 108 and a rear or stern end 110. Lateral side surfaces 109, 111, are formed on the opposite lateral side walls of the surfboard, transversely to the top and bottom side surfaces.

The bottom surface 106 of the surfboard body 102 is provided by a first set of grooves which form a frontmost ridge 112, a rear ridge 114, one or more

intervening ridges 116 and longitudinal sides ridges 118. Ridges 112, 114 and 116 extend transversely of body 102, while ridges 118 extend generally longitudinally of body 102 but converging toward one another. Side ridges 118 have side faces 120 and merge at their front ends 118a at the bow end 108 of the watercraft. Frontmost ridge 112 defines a bow surface 122 which is convex. The rear ridge 114 defines a stern groove surface 124 with a convex profile normal to said bottom surface 106, at a distance from the latter and of increasing inclination while approaching the top surface 104, wherein a stern groove is formed which opens freely at the stern open end mouth. As illustrated in figure 12, the intermediate groove 113 located between ridges 112 and 116 is downwardly convex. Lateral side surfaces 109, 111, of the surfboard are also provided with a second and a third set of grooves respectively which form a frontmost ridge 112• , 112' ' , a rearmost ridge 114• , 114' ' , and one or more intervening ridges 116', 116". Ridges 112', 112", 114', 114" and 116', 116" extend transversely of body 102. The rear ridges 114', 114", define a stern surface 124', 124", opening freely at a narrow stern end mouth thereof.

Again, all of the ridges 112, 112', 112", 114, 114', 114" and 116, 116', 116" are bowed away from front end 108, respectively. The exposed edge faces of ridges 112 to 118 collectively form bottom surface 106, while the grooves formed between the ridges of the lateral side surfaces 109, 111, form two water engaging pockets that converge toward one another at their front ends. The lateral ridges located on the side pockets

109, 111, of the surfboard 102 increase the total water drag surface and can therefore further increase the watercraft speed at water level. Moreover, these lateral ridges 112* , 114' , 116' , ... assist in maintaining the surfboard axially aligned with the direction of displacement over water, i.e. substantially prevent the

watercraft 102 from diverging relative to the axis of displacement thereof over water. Indeed, should the watercraft not be exactly orthogonal to the incoming waves on the water surface, or alternately parallel thereto depending on the choice of direction of the user, in a stationary condition thereof over water, upon forward motion of the surfboard 102, the lateral ridges will provide self-induced straightening of the watercraft. That is to say, the surfboard will automatically pivot under hydrodynamic forces to bring it exactly orthogonal to the waves, or exactly parallel thereto as the case may be.