Towable water sports apparatus such as a water ski

A towable water sports apparatus such as a water ski is provided with a narrowed waist portion in the forward half of the ski, a concave tunnel in the bottom surface of the ski which terminates in a Y-shaped end adjacent the tail end of the ski, a flex-adjusting plate which is secured to the top surface of the ski, and a vibration dampening cell which is positioned in a recess in the core of the ski and which is covered by the cover of the ski.

BACKGROUND AND SUMMARY 
This invention relates to a towable water sports apparatus such as a water 
ski, kneeboard, wakeboard, or waterski board. More particularly, the 
invention relates to a towable water sports apparatus which is provided 
with one or more features for improving the performance of the apparatus. 
Water skis, kneeboards, wakeboards, water ski boards and the like are 
designed to be towed behind a motor boat. The user stands, kneels, or sits 
on the device, and a tow rope is held by the user or attached to the 
device. Such devices conventionally include an elongated body having top 
and bottom surfaces, a forward end, a tail end, and a pair of sides. 
In accordance with one aspect of the invention, the body is provided with a 
narrowed waist portion in the forward half of the body. The waist portion 
is formed by inwardly concave portions of the sides. The waist portion 
permits better and more secure penetration of the body in the water before 
turns and better tracking during turns. The waist portion also reduces 
lift when pressure is exerted on the forward portion of the body. 
In accordance with another aspect of the invention, a flex-adjusting 
plate(s) is secured to the top surface of the body for controlling flex 
and performance of the apparatus. The plate is provided with a pair of 
elongated slots so that the position of the plate can be varied as desired 
for affecting the turning and accelerating characteristics of the 
apparatus. 
The bottom surface of the body may be provided with a concave tunnel which 
terminates in a generally Y-shaped end portion adjacent the tail end of 
the body. The Y-shaped end portion channels water flow in laterally 
outward directions and channels turbulence and air away from the tail of 
the apparatus where a fin may be located. 
Another aspect of the invention includes a vibration dampening cell which 
is positioned in a recess in the body. The body is advantageously formed 
from a molded core and a cover, and the recess is provided in the core. 
The vibration dampening cell absorbs or dampens vibration or chatter of 
the core and reduces vibration which is transmitted to the user of the 
apparatus.

DESCRIPTION OF SPECIFIC EMBODIMENTS 
The invention will be explained in conjunction with a water ski. However, 
it will be understood that the invention can also be used with other 
towable water sports devices such as kneeboards, waterski boards, 
wakeboards, etc. 
FIG. 1 illustrates a prior art slalom water ski 10 which is described in 
U.S. Pat. No. 4,795,386. The slalom water ski includes an elongated ski 
body 11 and a pair of foot bindings 12 and 13 which are mounted on the ski 
body along the longitudinal centerline 14 of the ski body. 
The ski body includes a forward end 16, a tail end 17, and a pair of sides 
18 and 19. The ski also includes a top surface 20 and a bottom surface 
(not shown). As described in U.S. Pat. No. 4,795,386, the bottom surface 
includes a concave tunnel. 
FIG. 2 illustrates a water ski 22 which is similar to the water ski 10 with 
the exception of a waist portion 23 in the forward portion of the ski. The 
water ski 22 includes a top surface 24, a bottom surface 25 (FIG. 6), a 
forward end 26, a tail end 27 (FIG. 6), and a pair of sides 28 and 29. The 
sides 28 and 29 extend concavely inwardly in the direction of the arrows A 
at 28a and 29a to form the narrowed waist portion 23 which is narrower 
than the portions of the water ski both forwardly and rearwardly of the 
waist portion. The concave portions 28a and 29a are gradually curved in a 
generally C-shape, and the width of the ski just forwardly of the waist 
portion is substantially the same as the width of the ski just rearwardly 
of the waist portion. 
The waist portion is located in the forward half of the ski, i.e., the 
portion of the ski which is forward of the longitudinal midpoint of the 
ski. The waist portion is preferably located forwardly of the foot binding 
on the ski. 
FIG. 3 illustrates a flex-adjusting plate 31 which can be secured to the 
water ski for controlling the stiffness or flexibility of the ski. The 
flex-adjusting plate 31 includes a tapered forward end 32, a rear end 33, 
and a pair of sides 34 and 35. A pair of elongated slots 36 are provided 
in the flex-adjusting plate for receiving threaded fasteners 37. The 
fasteners 37 secure the flex-adjusting plate to the ski by screwing into 
internally threaded cylindrical inserts 38 which are embedded in the body 
of the ski. The flex-adjusting plate is advantageously formed from 
aircraft-quality aluminum for high strength and durability. 
FIG. 4 illustrates three flex-adjusting plates 31 which are superimposed on 
each other and secured by the fasteners 37. The additional flex-adjusting 
plates further increase the stiffness of the ski. More or fewer adjusting 
plates can be used as desired. 
FIG. 5 illustrates the flex-adjusting plate 31 secured to the top surface 
of the water ski 22 in the waist portion 23. The slots 36 of the plate are 
aligned with the longitudinal centerline 40 of the ski, and the slots 
permit adjustment of the longitudinal position of the plate. 
If the water ski is formed with a waist portion 23, the flex-adjusting 
plate is preferably located in the waist portion. However, the 
flex-adjusting plate can be used on skis and other towable devices without 
a waist portion, or the flex-adjusting plate can be located in other 
portions of the ski. 
FIG. 6 illustrates the bottom surface 25 of the water ski and the concave 
tunnel 42 which is formed therein. The concave tunnel 42 extends 
longitudinally along the bottom of the ski and terminates in a Y-shaped 
end portion 43. The Y-shaped end portion 43 includes a pair of diverging 
tunnel portions 44 and 45 which diverge rearwardly and outwardly toward 
the sides 28 and 29 of the ski. The tunnel portion 42 narrows to a waist 
portion 46 just forwardly of the Y-shaped end portion 43. With the 
exception of the waist portion 46 and the Y-shaped end portion 43, the 
tunnel 42 can be otherwise conventional. 
The forward portion of the tunnel 42 channels water longitudinally in the 
direction of the arrow B. The diverting end portions 44 and 45 channel 
water outwardly away from the tail end in the directions of the arrows C 
and D. The end portions can extend at an angle of about 45.degree. to the 
longitudinal centerline of the ski. 
Referring now to FIG. 7, the water ski 22 includes a molded foam core 48 
and a laminated cover for the core which comprises a layer 49 of 
fiberglass and resin and a top skin 50 of ABS plastic or aluminum. Such 
molded cores and laminted covers are conventional and well known. 
The core 48 is provided with a recess or cavity 51 which is molded into the 
core, and a vibration dampening cell 52 is positioned in the recess before 
the cover is secured to the core. The vibration dampening cell is 
advantageously formed from a polyethylene bag which is filled with a 
viscous fluid. Preferably, the viscous fluid is biodegradable. 
When the cover is secured to the core in the conventional manner, the 
vibration dampening cell contacts both the core and the cover. The volume 
of the cell relative to the volume of the recess is preferably such that 
the cell is pressed into firm engagement with both the core and the cover. 
In a slalom ski the vibration dampening cell is advantageously located 
under the front foot binding. In a combo ski the cell can be located under 
the single foot binding. In other towable water sports devices, the cell 
can be located in the area where the user contacts the device. 
If desired, additional dampening can be obtained by using more recesses and 
cells or by using a larger recess and a larger cell. 
The various novel features which have been described herein can be used 
singly or in any combination desired. Each feature contributes independent 
advantages which can be realized without using other features. However, 
optimum performance is obtained when all of the features are used. 
The narrowed waist portion 23 in the forebody of the ski allows for better 
and more secure pre-turn penetration of the ski in the water and better 
ski tracking during the turn. The waist portion also reduces lift when 
pressure is exerted on the forebody of the ski by the skier. The skier is 
therefore able to carve tight turns and penetrate rough water with extra 
holding power. 
The sides 28 and 29 can be provided with sharp edges which allow the ski to 
set deeply and securely in the water during pre-turn, extension, and 
follow through. The result is a tigher, truer carve requiring much less 
body movement during the turning process and a stabilized ride throughout 
the course of skiing. 
The flex-adjusting plate 31 controls the stiffness characteristics of the 
ski. The location of the plate can be shifted to change the areas of 
stiffness and flex for customized performance. Adding or deleting plates 
and/or changing the position of plates can dramatically affect the turning 
or accelerating characteristics of a water ski, kneeboard, wakeboard, etc. 
Water skis and other towable products have inherent flexiblity. The 
flex-adjusting plate allows a user to control and adjust flexing and limit 
tip distortion and pre-turn dump by maintaining the designed forebody 
rocker and slope. It can also be used to control flex and distortion in 
other areas of water skis and other towable products. 
The Y-shaped tail end portion 43 of the concave tunnel 42 improves 
on-the-water performance and maneuverability. The diverging end portions 
44 and 45 serve as pressure release flutes which channel water flow in 
outward directions and allow the ski to sit more securely in the water. 
A water ski conventionally includes a fin on the bottom surface adjacent 
the tail end of the ski. The diverging portions 44 and 45 of the tunnel 
channel turbulence and air away from the fin, allowing the ski to track in 
a clean water flow. 
The pressure release flutes thereby hold the tail of the ski in the water 
and enhance stability and control at all speeds and in all conditions. The 
flutes also relieve pressure and drag in the tail during turns permitting 
the tail sweep to follow the curve of the forebody. 
The vibration dampening cell 52 reduces tip chatter and vibration. 
Vibration is dampened or absorbed by the viscous fluid, providing a 
smoother, more controllable ride. The dampening cell is particularly 
effective in rough or choppy water. 
While in the foregoing specification, a detailed description of a specific 
embodiment of the invention was set forth for the purpose of illustration, 
it will be understood that many of the details herein given may be varied 
considerably by those skilled in the art without departing from the spirit 
and scope of the invention.