Human controlled towable device for water surface and subsurface operation

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to towable devices for travel in a body of water and, more particularly, the invention relates to a human controlled towable device that may be maneuvered on and below the water surface.

2. Description of Related Technology

A variety of well known human controlled towable water sport devices such as water skis, knee boards, inflatable rafts, inner tubes, etc. are commonly used by water sports enthusiasts to travel at a relatively high speed on the surface of a body of water such as a river, a lake, an ocean, etc. Some of these water sport devices, such as inflatable rafts and inner tubes, are pulled over the water surface by a power boat using a towline such as a rope, cable, etc. that is connected between the water sport device and the power boat, while other water sport devices, such as water skis and knee boards, require the operator (i.e., the person using the water sport device) to fasten themselves to the water sport device via a boot, strap, etc. and to grasp a handle attached to one end of a towline that is pulled by a power boat.

The operator of the above-noted commonly available water sport devices may influence or control the lateral movement of some types of water sport devices on the water surface by adjusting the attitude of their body with respect to the orientation of the water sport device, the towline, etc. and/or by changing the heading of the water sport device relative to the heading of the power boat that is pulling the water sport device. For example, by leaning to one side of the water sport device being towed and/or by forcing the heading of the water sport device to rotate toward that same side, the operator may cause the water sport device to move laterally toward that side. Of course, such operator controlled lateral motion of the water sport device works well with water sport devices such as skis and knee boards that have an oblong footprint and relatively flat or thin profiles. On the other hand, the lateral motion of a water sport device such as, for example, an inner tube, may be very difficult, if not impossible, for the operator to control via body orientation and/or orientation of the water sport device with respect to the power boat, the surface of the water, etc. While many of the above-noted towable water sport devices may enable an operator to exert limited control over the manner in which the water sport device travels on the water surface, none of these commonly available water sport devices enables an operator to travel and maneuver below the surface of the water.

A number of technologies are currently available that enable human subsurface travel through a body of water (i.e., underwater travel). For example, snorkeling equipment enables underwater travel for short periods of time and self-contained underwater breathing apparatus (SCUBA), bathyspheres, bathyscaphs, etc. enable humans to travel underwater for extended periods of time. In the case of SCUBA and snorkeling equipment, an operator may also choose to use an aquascooter, which is a self-contained propulsion unit, to increase the speed of their underwater travel. However, none of the above-mentioned currently available subsurface or underwater travel devices are designed to be towed by a vehicle or water craft such as a power boat, sail boat, etc.

One known towable board for underwater swimming and riding on the surface of a body of water is disclosed by U.S. Pat. No. 5,655,939 to Salvadores. The towable board disclosed by Salvadores has a substantially unitary and planar body that includes a pair of wing-shaped lobes, which are symmetrically disposed on opposing sides of a central axis of the towable board. The towable board further includes a pair of fins, each of which extends perpendicularly from a bottom surface of a respective one of the wing-shaped lobes. In operation, the towable board disclosed by Salvadores is pulled by a power boat via a towline while an operator grips the towable board using a pair of slot-shaped openings that extend through the towable board adjacent to the leading edge of each of the wing-shaped lobes. The operator may maneuver the towable board by rotating the board about an axis perpendicular to the water surface, thereby causing the fins to travel through the water at an angle with respect to the heading of the towline, which results in a lateral motion of the towable board in the direction of the rotation. To submerse the towable board or to change the depth at which the towable board is moving, the operator may push downward on the leading edges of the wing-shaped lobes using the slot-shaped openings in the towable board.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, a device for use in water surface and subsurface travel may include a towbar having first and second end portions and a first control member rotatably coupled to the towbar adjacent to the first end portion. The first control member may have a first control surface and a second control surface opposite the first control surface. The device may further include a second control member rotatably coupled to the towbar adjacent to the second end portion and spaced from the first control member. The second control member may have a third control surface and a fourth control surface opposite the third control surface. The device may further include first and second grips spaced apart and fixed to the towbar between the first and second control members so that rotation of the first and second grips about a longitudinal axis of the towbar causes the first and second control members to rotate about the longitudinal axis of the towbar. Additionally, a towline connector may be fixed to the towbar between the first and second grips.

In accordance with another aspect of the invention, a device for use in water surface and subsurface travel may include a towbar having a longitudinal axis and a first control member rotatably coupled to the towbar. The first control member may be rotatable about the longitudinal axis of the towbar and the device may include a second control member that is rotatably coupled to the towbar. The second control member may be rotatable about the longitudinal axis of the towbar independently from the first control member. Additionally, the device may include a connector fixed to the towbar for connecting the towbar to a towline.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is an exemplary isometric view of a device for use in human controlled water surface and subsurface travel;

FIG. 2

is an exemplary plan view of one manner in which control members may be adjustably fixed to the towable device;

FIG. 3

is an exemplary plan view of an adjustable towline connector that may be used with the towable device;

FIG. 4

is an exemplary sectional view of another adjustable towline connector that may be used with the towable device;

FIG. 5

a

is an exemplary side view of yet another towline connector that enables rapid disconnection of a towline and which may be used with the towable device;

FIG. 5

b

is a front sectional view of the towline connector shown in

FIG. 5

a

;

FIG. 6

is an exemplary isometric view illustrating one manner in which handgrips may be used with the towable device;

FIGS. 7-11

are exemplary views of alternative handgrip designs that may be used with the towable device;

FIG. 12A

is an exemplary isometric view of a control member having a movable trailing edge that may be used with the towable device;

FIG. 12B

is an exemplary front view of a control member that has a variable control surface area;

FIG. 12C

is an exemplary front view of another control member that has a variable control surface area;

FIG. 13

is an exemplary plan view, partially in section, of a gear set that may be interposed between the handgrips and the control members of the towable device;

FIG. 14

is an exemplary side view of a chassis that may be used with the towable device;

FIG. 15

is an exemplary side view of another chassis that may be used with the towable device;

FIG. 16

is an exemplary plan view of a rudder that may be used with the towable device;

FIG. 17

is an exemplary side view of yet another chassis that may be used with the towable device;

FIG. 18

is an exemplary front view, partially in section, of another rudder that may be used with the towable device;

FIG. 19

is an exemplary side view illustrating one manner in which the towable device chassis may provide openings to permit movement of the towbar relative the chassis;

FIG. 20

is an exemplary front sectional view illustrating one manner in which air tanks and a flotation pad may be fixed to the chassis of the towable device;

FIG. 21

is an exemplary diagrammatic view illustrating one manner in which air may be provided to an operator of the towable device from a remote location;

FIG. 22

is an exemplary diagrammatic view of a buoyant indicator that may be used with the towable device;

FIG. 23

is an exemplary diagrammatic view of a towline mechanism that may be used with the towable device;

FIGS. 24 and 25

are exemplary front and side diagrammatic views, respectively, of a propulsion system that may be used with the towable device;

FIG. 26

is an exemplary sectional side view of a nozzle assembly that may be used with the towable device propulsion system;

FIG. 27

is a more detailed diagrammatic view of the propulsion system shown in

FIGS. 25 and 26

;

FIGS. 28 and 29

are exemplary cross-sectional views of a water release gate assembly that may be used with the towable device propulsion system; and

FIGS. 30 and 31

are exemplary cross-sectional views of yet another water release gate assembly that may be used with the towable device propulsion system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1

is an exemplary isometric view of a human controlled towable device

10

that enables a human operator to maneuver on and below the surface of a body of water such as, for example, a river, a lake, an ocean, etc. As shown in

FIG. 1

, the towable device

10

includes a towbar assembly

12

having a longitudinal axis

14

, a first end portion

16

and a second end portion

18

. The towbar assembly

12

may also include a first control member

20

, a second control member

22

, handgrips

24

and

26

and a towline connector

28

.

The towbar assembly

12

may include a rigid frame member

30

made of steel, plastic, aluminum or any other suitable material that preferably, but not necessarily, provides a lightweight, corrosion-resistant characteristic. By way of example only, the rigid frame member

30

may be made from aluminum or steel bar stock, thick-walled or thin-walled tubing, etc. to provide sufficient strength and durability for the towable device

10

in a marine or in any other water environment. Additionally, while the towbar assembly

12

is shown in

FIG. 1

as having a single rigid frame member

30

, a more complex frame having a plurality of interconnected frame members may be used instead to provide a rigid structure to which the control members

20

and

22

, the handgrips

24

and

26

and the towline connector

28

may be fixed.

The towbar assembly

12

may further include shafts or sleeves

32

and

34

, which are best seen in

FIG. 6

, that are rotatably coupled to the rigid frame member

30

using any suitable bearing and retention mechanisms. By way of example only, the sleeves

32

and

34

may be designed as bushings that are rotatably engaged with protrusions or axles (not shown) that are integral with or attached to the rigid frame member

30

. The ends of the protrusions or axles may be threaded to accept lock nuts, such as locknut

40

, so that the control members

20

and

22

, the sleeves

32

and

34

and the handgrips

24

and

26

may be fastened to the towbar assembly

12

. Alternatively or additionally, the control members

20

and

22

, the handgrips

24

and

26

and the sleeves

32

and

34

may be assembled to the rigid frame member

30

using push nuts, circlips, cotter pins, etc. or any combination thereof. Still further, in the case where the sleeves

32

and

34

form bushings that rotate about respective protrusions from the rigid frame member

30

, the sleeves

32

and

34

may be made completely or partially of a self-lubricating material such as, for example, Teflon. In any event, as can be seen from

FIG. 1

in conjunction with the above discussion, the handgrips

24

and

26

may be manipulated to cause the control members

20

and

22

to independently rotate about the longitudinal axis

14

of the towbar assembly

12

.

As shown in

FIG. 1

, the control members

20

and

22

have respective upper control surfaces

42

and

44

, lower control surfaces

46

and

48

, leading edges

50

and

52

and trailing edges

54

and

56

. While the control members

20

and

22

are depicted as having an airfoil type profile similar to that of a plane wing, other profiles may be used instead without departing from the scope and the spirit of the invention. The control members

20

and

22

may each include a plurality of respective bores or mounting holes

58

-

60

and

61

-

63

that pass through the control members

20

and

22

and that have axes which are substantially parallel to the leading edges

50

and

52

of the control members

20

and

22

and to the longitudinal axis

14

of the towbar assembly

12

. As shown in

FIG. 1

, the mounting hole pairs

58

and

61

,

59

and

62

, and

60

and

63

may be at different distances from the leading edges

50

and

52

. In this manner, the distance between the leading edges

50

and

52

of the control members

20

and

22

may be varied or adjusted in a discrete or stepwise manner to achieve a desirable operational characteristic. For example, increasing the distance between the leading edges

50

and

52

and the longitudinal axis

14

of the towbar assembly

12

may decrease the effort required to rotate the control members

20

and

22

about the longitudinal axis

14

but may also decrease stability of the device

10

while it is being pulled through water. On the other hand, decreasing the distance between the leading edges

50

and

52

and the longitudinal axis

14

of the towbar assembly

12

may increase stability of the device

10

while it is being pulled through water but may also increase the amount of effort or force required to rotate the control members

20

and

22

about the longitudinal axis

14

.

It should be recognized that while three mounting holes are shown in each of the control members

20

and

22

, more or fewer mounting holes may be used if desired. Additionally, while the mounting holes

58

-

63

are shown by way of example to have substantially circular outer perimeters, any other perimeter or cross-sectional geometry may be used instead. For example, the mounting holes

58

-

63

may have generally polygonal or any other non-circular outer perimeter geometry that mates with a similar or identical perimeter geometry of the outer surfaces of the shafts or sleeves

32

and

34

to thereby key or lock the control members

20

and

22

to the sleeves

32

and

34

. Of course, in the illustrated embodiments, the inner perimeters of the sleeves

32

and

34

are substantially circular to enable the sleeves

32

and

34

to freely rotate over the bearing surfaces of the protrusions or axles that extend from the rigid frame member

30

. Still further, the control members

20

and

22

may be rotatably fixed with respect to the respective sleeves

32

and

34

using any other desired mechanism such as a channel and key arrangement, welding, gluing, a press fit, etc. However, in some cases it may be desirable to use fastening and/or keying mechanisms that enable easy removal and replacement of the control members

20

and

22

. For example, a variety of control member designs having different control surface contours, sizes, etc. may be provided so that an operator can selectively attach a particular one of the control member designs to achieve a desired operational characteristic. In general, an operator's height, weight, strength, as well as an operator's desired stability, speed, maneuverability, etc. characteristics may affect the optimal control member selection.

The control members

20

and

22

may be made of any suitable material such as, for example, lightweight plastics and/or metals that are sufficiently strong and durable in a marine or water environment. For example, the control members may be injection molded from a thermoplastic or an elastomeric material, machined from a plastic or a metal material and/or may be fabricated via welding, gluing, using fasteners, etc. using multiple component parts. To minimize weight and cost, the control members

20

and

22

may be partially or completely hollow or may have relieved areas (e.g., pockets, cavities, depressions, etc.) distributed over the control surfaces

42

-

48

.

The handgrips

24

and

26

are fixed to the outer surfaces of the respective sleeves

32

and

34

so that rotation of the handgrips

24

and

26

about the longitudinal axis

14

causes the sleeves

32

and

34

and the control members

20

and

22

to rotate about the longitudinal axis

14

. Of course, because the control members

20

and

22

are independently rotatable, one of the handgrips

24

and

26

may be rotated in one direction about the longitudinal axis

14

while the other one of the handgrips

24

and

26

may be rotated in another direction about the longitudinal axis

14

. The handgrips

24

and

26

may be made of any suitable material such as, for example, a metal, which may include knurled potions that facilitate griping by an operator, a foam or other spongy material that can be easily gripped by an operator, a plastic material, etc. As shown in

FIG. 1

, the handgrips

24

and

26

may be press fit, glued, or fixed in any other desired manner to the sleeves

32

and

34

. Still further, while the handgrips

24

and

26

are depicted as being separate components that are fixed to the sleeves

32

and

34

, the handgrips

24

and

26

may instead be integrally formed with the sleeves

32

and

34

. For example, the sleeves

32

and

34

may be provided with larger diameter portions, knurled portions, or any other dimensions or features that facilitate an operator's rotating of the control members

20

and

22

. The towline connector

28

may be a U-shaped or a V-shaped component that is fixed to the rigid frame member

30

via bolts, screws and/or welds and is preferably, but not necessarily, disposed substantially centrally between the control members

20

and

22

and the handgrips

24

and

26

.

In operation, the towable device

10

may be used in a body of water such as a river, a lake, an ocean, etc. and may be connected to a tow vehicle such as, for example, a power boat, a sail boat, a row boat, etc. via a towline. An operator may enter the body of water and grasp the handgrips

24

and

26

while lying in a prone or face-down position in the water. As the towable device

10

and its operator are pulled by the tow vehicle through the water, the operator may maneuver through the water by rotating the control members

20

and

22

via the handgrips

24

and

26

and/or by manipulating their body orientation in the water and with respect to the towable device

10

. For example, rotating the trailing edges

54

and

56

of both control members

20

and

22

upward and toward the towline connector

28

(and the towline) causes the towable device

10

to submerge or to dive in the water. On the other hand, rotating the control members

20

and

22

so that the trailing edges

54

and

56

rotate downward causing the towable device

10

and its operator to climb toward the water surface. Still further, rotating the control members

20

and

22

in opposing directions causes the towable device

10

and its operator to travel in a spiraling manner through the water. Still further, by changing the rotations of the control members

20

and

22

so that both of the trailing edges

54

and

56

are alternately rotated upward and downward at the same time, an operator may cause the towable device

10

to porpoise (i.e., to alternately jump out of and dive into the water). Of course, an operator may alternatively or additionally manipulate their body by, for example, leaning to one side or the other, changing the orientation of their legs or arms, etc. to maneuver through the water. Additionally, mechanical stops may be provided within the towable device

10

to limit the angle through which the control members

20

and

22

may be rotated. In this manner, stalling, dangerous maneuvers, etc. may be minimized or prevented.

Preferably, but not necessarily, the towable device

10

is made of one or more materials and is configured so that the towable device

10

floats in water when in a static or rest condition, thereby simplifying an operator's effort to mount or grab the towable device

10

and/or simplifying recovery of the towable device

10

in the event that an operator loses their grip during use and becomes separated from the device

10

.

FIG. 2

is an exemplary plan view of an alternative control member design that may be used with the towable device described herein to enable a continuous adjustment of the distance between the leading edge of the control member and the rotational axis of the control member. As shown in

FIG. 2

, a control member

70

having a leading edge

72

and a trailing edge

74

includes a passage

76

therethrough that is substantially parallel to the leading edge

72

and to the trailing edge

74

. The passage

76

may have an oblong cross section such as, for example, an oval-shaped or rectangular cross section. However, any other cross section may be used instead. A rotatable shaft or sleeve

78

, which may be similar or identical to the shafts or sleeves

32

and

34

shown in

FIG. 1

, traverses the passage

76

. Threaded adjusting screws

80

and

82

pass through respective openings

84

and

86

in the control member

70

through threaded bores

88

and

90

in the sleeve

78

and into blind holes

92

and

94

. Thus, by rotating the screws

80

and

82

either clockwise or counterclockwise, the sleeve

78

may be moved toward or away from the leading edge

72

of the control member

70

.

FIG. 3

is an exemplary plan view of an adjustable towline connector

100

that may be used with the towable device described herein. The towline connector

100

shown in

FIG. 3

includes an eye bolt

102

having a towing eye

103

, a threaded portion

104

and a pair of locknuts

106

and

108

. The threaded portion

104

of the eye bolt

102

passes through a rigid frame member

110

, which may be similar or identical to the rigid frame member

30

shown in

FIG. 1

, via a bore

112

. As can be seen from

FIG. 3

, the distance between the towing eye

103

and the rigid frame member

110

may be set to any desired distance that permits the locknuts

106

and

108

to be tightened to lock or fix the position of the towing eye

103

. Thus, an operator may vary the position of the towing eye

103

to achieve a desired feel or operational characteristic of the towable device described herein.

FIG. 4

is an exemplary sectional view of another adjustable towline connector

120

that may be used with the towable device described herein. The towline connector

120

includes an eye bolt

122

having a towing eye portion

124

and a shaft portion

126

which has a plurality of bores or holes

128

-

132

therethrough. The shaft portion

126

of the connector

120

passes through a bore

134

in a rigid frame member

136

, which may be similar or identical to the frame member

30

shown in

FIG. 1

, and a pin

138

passes through the frame member

136

and one of the plurality of holes

128

-

132

to fix the connector

120

to the frame member

136

. As can be seen in

FIG. 4

, the distance between the towing eye

124

and the frame member

136

may be varied in discrete amounts by fixing the eye bolt

122

to the frame member

136

using different ones of the holes

128

-

132

. For example, when the hole

128

is used, the towing eye

124

is nearer to the frame member

136

than when the hole

132

is used.

FIG. 5

a

is an exemplary side view of yet another towline connector

150

that enables rapid disconnection of a towline and which may be used with the towable device described herein, and

FIG. 5

b

is a front sectional view of the towline connector

150

shown in

FIG. 5

a

. The towline connector

150

includes a curved arm

152

having a first arm portion

154

and a second arm portion

156

that rotate about a pivot

157

. The first arm portion

154

has a finger portion

158

that stops against a surface

160

of a rigid frame member

162

that may, for example, be a part of the rigid frame member

30

(

FIG. 1

) of the towable device described herein. The second arm portion

156

includes a detent

164

for receiving a pin

166

as shown in

FIGS. 5

a

and

5

b.

In operation, the pin

166

may be removed to enable the first arm portion

154

and the finger portion

158

to be rotated away from the surface

160

of the frame member

162

. A towline loop, eye, etc. may then be passed over the first arm portion

154

and the first arm portion

154

may be rotated so that the finger

158

contacts the surface

160

so that the pin

166

may be inserted into the frame member

162

as shown in

FIGS. 5

a

and

5

b

to lock the towline connector

150

in position. In use, an operator may remove the pin

166

from the frame member

162

to unlock the connector

150

so that the towline may be pulled free from the connector

150

. In this manner, the towable device described herein may be quickly released from the tow vehicle in, for example, a dangerous or panic situation.

FIG. 6

is an exemplary isometric view generally illustrating one manner in which handgrips

200

and

202

may be used with the towable device described herein. As shown in

FIG. 6

, the handgrips

200

and

202

are fixed to respective ones of the rotatable shafts or sleeves

32

and

34

so that rotation of the handgrips

200

and

202

about the longitudinal axis

14

of the towbar assembly

12

causes the control members

20

and

22

to rotate about the longitudinal axis

14

. Generally speaking, the handgrips

200

and

202

may be fixed to the sleeves

32

and

34

of the towbar assembly

12

via bores through the sleeves

32

and

34

that are preferably, but not necessarily, substantially transverse to the longitudinal axis

14

of the towbar assembly

12

.

FIGS. 7-11

are exemplary views of alternative handgrip designs that may be used with the towable device described herein. In particular,

FIG. 7

is an exemplary side view, partially in section, of a grip or handgrip

210

that may be used with the towable device described herein. The handgrip

210

includes an elongated griping portion

212

and a shaft portion

214

that is spaced from the elongated griping portion

212

. The shaft portion

214

includes a plurality of bores

216

-

220

that enable the elongated griping portion

212

to be fixed at one of several possible distances from the longitudinal axis

14

of the towbar assembly described herein. As shown in

FIG. 7

, the shaft portion

214

of the handgrip

210

may be inserted into a bore

222

that passes through a rotatable shaft or sleeve

224

, which may be similar or identical to the shafts or sleeves

32

and

34

shown in FIG.

1

. The shaft or sleeve

224

may include another bore

226

, which is substantially transverse to the bore

222

, for receiving a pin

228

that locks the handgrip

210

to the rotatable sleeve

224

. Thus, when the bore

226

is substantially coaxially aligned with one of the plurality of holes

216

-

220

, the pin

228

may be used to fix or to lock the handgrip

210

to the sleeve

224

.

FIG. 8

is an exemplary side view, partially in section, of another grip or handgrip

230

that may be used with the towable device described herein. The handgrip

230

may include an elongated griping portion

232

and a shaft portion

234

that includes a threaded portion

236

. The handgrip

230

may be fixed to the shaft or sleeve

224

by tightening lock nuts

238

and

240

against the sleeve

224

. In contrast to the handgrip

210

shown in

FIG. 7

, the distance between the elongated griping portion

232

and the axis of rotation of the sleeve

224

may be adjusted in a continuous rather than a discrete or stepped manner.

FIG. 9

is an exemplary side view, partially in section, of still another handgrip

250

that may be used with the towable device described herein. The handgrip

250

includes an elongated griping portion

252

and a shaft portion

254

having a threaded portion

256

. The handgrip

250

shown in

FIG. 9

may be fixed to the shaft or sleeve

224

using the locknuts

238

and

240

.

FIG. 10

is an exemplary isometric view of a towable device

274

that uses yet another type of handgrip

275

, and

FIG. 11

is an enlarged diagrammatic view of the handgrip

275

shown in

FIG. 10

that illustrates the manner in which an operator's hand

277

may grasp the handgrip

275

. As best shown in

FIG. 11

, the handgrip

275

has an outer perimeter

279

that defines an opening

280

and which has a first side

282

and a second opposing side

284

. The first and second sides

282

and

284

are preferably, but not necessarily, integral with a rotatable shaft or sleeve

286

, which may be similar or identical to the shafts or sleeves

32

and

34

shown in FIG.

1

. The handgrip

275

may also include an elongated griping portion

288

that traverses the opening

280

and which has a longitudinal axis

290

that forms a non-zero angle with respect to a longitudinal axis

292

of the rotatable shaft or sleeve

286

and, thus, forms a non-zero angle with respect to a longitudinal axis

294

(

FIG. 10

) of the towable device

274

.

FIG. 12A

is an exemplary isometric view of a control member

300

having a movable trailing edge

302

that may be used with the towable device described herein. A rotatable shaft or sleeve

304

may include a toothed portion

306

that drives a chain or toothed belt

308

that, in turn, may be used to rotate a pulley or gear

310

to cause the trailing edge

302

to rotate or pivot about an axis

312

, which may be substantially parallel to a longitudinal axis

314

of the shaft or sleeve

304

. Although

FIG. 12A

illustrates the movement of the trailing edge

302

as being carried out using a belt or a chain, any other suitable drive mechanism may be used instead, such as, for example, direct drive gearing (i.e., a transmission), push rods and lever arms, fluid or hydraulic coupling, etc.

FIG. 12B

is an exemplary front view of a control member

315

having a variable control surface area that may be used with the towable device described herein. The control member

315

includes an outer portion or panel

316

and an inner portion or panel

317

that is slidingly engaged with the outer panel

316

. Thus, the inner panel

317

may be telescopically extended to increase the exposed surface area of the control member

315

or, alternatively, the inner panel

317

may be telescopically compressed with respect to the outer panel

316

to decrease the exposed surface area of the control member

315

. The control member may further include a pin

318

for locking the relative positions of the inner and outer panels

316

and

317

. The inner panel

317

may be shaped so that variation of the position of the inner panel

317

with respect to the outer panel

316

results in a continuous or, alternatively, a stepped, variation of the exposed surface area of the control member

315

.

FIG. 12C

is an exemplary front view of another control member

320

having a variable control surface area that may be used with the towable device described herein. The control member

320

includes a primary portion or panel

321

and an extension portion or panel

322

that is coupled to the primary panel

321

via a hinge

323

. The extension panel

322

may be folded against the primary panel

321

as indicated by the dashed lines

324

to reduce the effective surface area of the control member

320

. The control member

320

may further include a locking mechanism

325

that locks the extension panel

322

in an extended or unfolded position as shown in FIG.

12

C. The locking mechanism

325

may be implemented using a U-shaped pin that may be pressed into bores that extend partially or completely through adjacent portions of the primary and extension panels

321

and

322

.

In operation, a control member having a variable control surface area, such as those exemplary control members shown in

FIGS. 12B and 12C

, provides several advantages. For example, the control surface area may be increased during relatively low speed operation to increase or improve maneuverability. Conversely, the control surface area may be decreased during relatively high speed operation to reduce drag and stress on the control member. Additionally, the retracted, folded or minimal area condition for the control members may be used to reduce the overall footprint of the towable device to thereby facilitate storage of the device within a relatively small area or volume.

FIG. 13

is an exemplary plan view, partially in section, of a dual ratio (i.e., two speed) transmission or gear set

340

that may be interposed between the handgrips and the control members of the towable device described herein. As shown in

FIG. 13

, a rotatable shaft or sleeve