Fluke Board...A Fluky Fusion of Fun and Fitness

Abstract

The ‘Fluke Board’ is a human-powered, hydrodynamic ride-on board/structure, which functions under water but has buoyancy and is operated via the rider's hands or via the rider's feet. The rider thrusts the ‘Fluke Board’ up and down in the water, in the manner of a fluke or flipper, to produce forward motion through the water. The ‘Fluke Board’ therefore has unique features and functions that distinguish it from existing ride-on boards. The ‘Fluke Board’ rider, regardless of their age, experiences fun and exercise, which promote fitness and good health.

Description

BACKGROUND

What is the ‘Fluke Board’?

The ‘Fluke Board’ is a human-powered, hydrodynamic ride-on board/structure, which functions under water but has buoyancy and is operated via the rider's hands or via the rider's feet.

The ‘Fluke Board’ is a ‘green invention’, owing to its minimal environmental footprint and by its promoting recreation and travel without the use of fossil fuels.

How does the Rider Operate the ‘Fluke Board’?

The two basic postures for riding on the ‘Fluke Board’ are the ‘lying prone posture’ and the ‘standing/crouching posture’.

It is recommended that the rider wear a wetsuit or floatation vest for safety and added efficacy and enjoyment while riding the ‘Fluke Board’, even with the use of a higher buoyancy ‘Fluke Board’.

While operating the ‘Fluke Board’, the rider may wish to use swimming goggles for improved visibility and eye comfort, especially in salt water.

The ‘Lying Prone Posture’

In the ‘lying prone posture’, the rider lies horizontally in the water, as with swimming and grips the sides of the ‘Fluke Board’, or grips handles which may be formed in, or attached on the ‘Fluke Board’, with his/her hands and operates the ‘Fluke Board’ by pushing it down into the water and pulling it back up in a cyclical thrusting action, centered at the abdomen or waist of the rider.

The rider controls the forward or backward tilt of the ‘fluke Board’ during the said thrusting, returning to the horizontal before/after each thrust.

Propulsion is achieved by tilting the front of the ‘Fluke Board’ down during the down-thrusting action and up during the up-thrusting action to produce a fluke-like or flipper-like effect.

The hands/handles are positioned forward of the centre of mass of the ‘Fluke Board’.

The said tilting is achieved naturally by the said position of the hands, which creates a forwardly placed pivot point, but the angle is also controlled manually. Flatter angles are naturally achieved by positioning the hands nearer to the mid point of the ‘Fluke Board’, while steeper angles are naturally achieved by positioning the grip further forward.

This ability to alter the degree of tilt, combined with the chosen amount of force exerted by the arms, allows the ‘lying prone posture’ rider of the ‘Fluke Board’ to vary his/her acceleration and velocity.

There is skill in achieving a rhythm while operating the ‘Fluke Board’. A coordinated action of the rider's head, torso and lower limbs, in the manner of a dolphin or a swimmer performing the butterfly stroke, produces a more efficient, rhythmic operation of the ‘Fluke Board’ when greater speeds are desired, such as for catching a wave, racing against competitors, or achieving the ‘standing/crouching posture’ from a moving start.

Note that the exertion of force in thrusting the ‘Fluke Board’ also causes the rider's body to be thrust/accelerated in the opposite direction. During this acceleration the body of the rider is also being tilted, opposite to the ‘Fluke Board’ and is therefore also acting on the water to cause forward propulsion. Both the body of the rider and the ‘Fluke Board’ return to the horizontal before each thrust.

The weight and vertical inertia/momentum of the rider's body enhances the force being exerted on the ‘Fluke Board’ during a thrusting action and generates more forward propulsion. Rapid transition from one thrust to the next is beneficial because a greater force and acceleration can be exerted if greater speed is desired.

The thrusting action is more efficient when in line with the abdomen or waist of the Rider because this position is close to the point of the rider's centre of body mass, where inertia/momentum is greater. Therefore greater forces can be exerted on the ‘Fluke Board’ from this position of thrusting.

More buoyancy of the rider, such as while wearing a wetsuit or operating the ‘Fluke Board’ in salt water, allows a more powerful up-thrusting force on the ‘Fluke Board’. The down-thrust is weaker, as the rider is lighter in the water.

The rider returns to the surface for a breath, if desired, at the end of each down-thrusting action, similar to the action of taking a breath while performing the ‘butterfly stroke’ in swimming.

If the rider is on the surface of the water and therefore largely without the weight-negating effect of the water, at the time of a down-thrusting action, then there is an advantage of the greater weight of the rider's body to generate the down-thrust of the ‘Fluke Board’ and also the advantage of less drag as the body travels forward in the water.

Therefore the efficiency of operating the ‘Fluke Board’ is greatest when the rider's buoyancy is great enough to float to the surface after the up-thrusting action. Note that in the up-thrusting action, the rider is momentarily drawn below the surface of the water.

Small ‘Fluke Boards’, while being light and maneuverable for the described ‘fluking’ action, may also be used in a nearly horizontal thrusting action, which pulls the rider forwards in an oar-like action to achieve a rapid forward acceleration. A cutting forward action, which returns the ‘Fluke Board’ for the next thrusting action is achieved with the ‘Fluke Board’ pitched near the horizontal. For this cyclical thrusting action, handles should be angled obliquely. This enables the rider to maintain a strong hand-grip when tilting the ‘Fluke Board’ between near vertical and near horizontal. The shape of ‘Fluke Board’ which is suitable for this style of propulsion is short with scalloping of the leading edge to avoid collision with the rider.

The ‘Standing/Crouching Posture’

In the ‘standing/crouching posture’ the rider either stands with feet placed forward and backward on the ‘Fluke Board’, with body facing obliquely forward, similar to a conventional surfboard riding style, or with feet placed side-by-side and rider facing forwards, which especially suits the rider that is using a shorter ‘Fluke Board’.

With the side-by side foot position the rider relies on a forward placed pivot line to naturally create forward tilt in a down-thrust action and back tilt in the return or up-thrusting action, as with the forwardly placed hand grip in the ‘lying prone posture’ riding style as described above.

With the foot positioning, where one is placed forward and the other aft on the ‘Fluke Board’, the tilt is controlled deliberately using weight transfer.

Frictional contact of the rider with the ‘Fluke Board’ is provided with the use of elasticized rubber guy ropes strapped to the wrists, forearms or shoulders of the rider. The guy ropes may be attached to front and rear, or to both sides of the ‘Fluke Board’.

An alternative or additional beneficial system of attachment might involve flexible foot housings, such as exist with a flipper foot attachment/housing, but these would involve the risk of discomfort to the rider following prolonged use and may reduce balance correction maneuvers. Foot housings, which are already in existence, are not being claimed or illustrated.

When the ‘Fluke Board’ has vertical ‘Side Fins’, which have handles, (see details in specifications section) both feet can be placed on the board in a side-by-side position, while the rider is crouching with the hands grasping the handles. This posture can be achieved only while riding a wave.

Getting up into the ‘standing/crouching posture’ may be similar to the style of conventional surfboards, where forward movement is first achieved in the lying position, as described above, before the rider jumps to his/her feet.

The rider jumps to his/her feet at the end of an up-thrust of the ‘Fluke Board’, when the ‘Fluke Board’ is most shallow and less drag force is in effect, even though the up-thrust of the ‘Fluke Board’ results in the rider being drawn deeper. Therefore, this action of jumping to the ‘standing crouching posture’ is aided by a wetsuit or floatation vest worn by the rider, which also allows a more forceful up-thrust and increased forward momentum.

A forceful downward thrust of the ‘Fluke Board’ is then achieved through a jumping up/kicking down action of the rider, with ‘Fluke Board’ angled, shallowly, front-down.

If enough forward and upward momentum of the rider is achieved from this initial thrust and if the ‘Fluke Board’ remains shallow enough, the rider rapidly crouches again, while pulling on said guy ropes, using a front-up tilt. In this way the ‘Fluke Board’ is thrust upwards and a further forward movement is achieved.

The rider then continues by repeating the above actions, using sudden transition movements to take advantage of vertical momentum/inertia. This action, when performed successfully, is relatively physically demanding, especially with a ‘Fluke Board’ with less buoyancy.

To achieve a good speed the ‘Fluke Board’ must be kept quite shallow, again aided by the ‘Fluke Board’ having more buoyancy.

If this said shallowness and speed are not achieved, the action of kicking down followed by pulling up is easier to perform, as timing and force applied are no longer as crucial. This style of riding the ‘Fluke Board’ is more relaxing and can be performed at a leisurely pace, especially while wearing buoyancy clothing and is reminiscent of the feel when using the ‘Fluke Board’ while diving.

It is also possible to do a standing start to commence ‘Fluke Board’ riding in the ‘standing/crouching posture’. In this method the ‘Fluke Board’ is slowly pushed down into the water to be positioned under the crouching rider's feet, which are positioned front and rear, or side-by-side, as noted above. The rider uses said guy ropes, typically strapped to his wrists to allow foot grip and control of tilt. The thrusting actions are then as noted above for the ‘standing/crouching posture’ Fluke Board' riding style, starting with the jumping up/kicking down thrusting action. Using this technique to start it can be harder to go fast and achieve a shallower ride. As noted previously, a higher buoyancy board and a wetsuit is beneficial for the ‘standing crouching posture’ riding style which commences from a standing start.

The said guy rope not only allows the ‘standing/crouching’ rider a firm footing on the

‘Fluke Board’ but also a greater ability for lateral tilting and rotation to produce turning.

Wave Riding

While riding the ‘Fluke Board’ on a wave the ‘standing/crouching posture’ is achieved more easily and may even be achieved on shorter boards normally reserved for use in the ‘lying prone posture’, as noted above.

Most ‘Fluke Boards’, being wider and shorter than conventional surfboards, will not be ideally shaped or balanced for riding a wave sideways, as with conventional boards and would generally be used for surfing at angles aiming more towards the shore. The exception to this would be if a rider chose a shape and buoyancy of ‘Fluke Board’ to suit surfing, that being a longer and narrower board with more buoyancy, which are also the features that are suited to the easier use of the ‘Fluke Board’ in the ‘standing/crouching posture’ use.

The process the ‘Fluke Board’ rider usually uses to achieve wave riding is to begin with the fluking action, usually in the ‘lying prone posture’, to ‘catch’ the wave.

The ‘Fluke Board’, once in motion on the wave, skims on the surface, aided by the slope and forward motion of the wave. The ‘Fluke Board's’ skimming on the surface allows the rider to jump up into the ‘standing/crouching posture’ more easily, again with the use of said optional guy ropes or handles, or freestanding.

While riding a ‘Fluke Board’ on a wave the action of jumping up into a ‘standing/crouching posture’ is similar to the style used on a conventional surfboard and made easier with a more buoyant ‘Fluke Board’.

Turning

The ‘Fluke Board’ rider changes direction in three ways, namely by tilting left or right, rotating or, if in the ‘lying prone posture’, transposing the ‘Fluke Board’ to the left or right in a sweeping motion.

Variations in Size, Buoyancy and Shape

The choice of size and buoyancy of the ‘Fluke Board’ depends on the rider's characteristics of weight, strength, and preferred riding style, with higher buoyancy suiting the heavier rider and making for easier use of the ‘standing/crouching posture’ and wave riding.

With appropriate buoyancy being such a crucial factor in the varied uses of the ‘Fluke Board’ and varied weights of riders, there is a great advantage in ‘variable buoyancy’ ‘Fluke Boards’, which are discussed in the specifications section.

Larger dimensioned ‘Fluke Boards’ would suit the stronger and taller rider.

Shorter boards are more suited to use in the ‘lying prone posture’ and the side-by-side foot position with laterally anchored guy ropes or suitably positioned handles, as noted in the specifications section.

The shape of ‘Fluke Board’ may be a matter of style preference or may be a matter of preference of the rider for specific use of one of the two postures or a preference for using both postures.

What are the Recommended Uses of the ‘Fluke Board’?

The ‘Fluke Board’ may be used for riding waves, either in the manner of a conventional surfboard, freestanding or optionally using the said guy rope/s for increased stability and control, or using handles on side fins in the ‘crouching posture’, as detailed later. It may also be used in the manner of a ‘boogy board’.

The ‘Fluke Board’ may be used to achieve forward propulsion in flat water such as in bays, lagoons, harbors, large rivers, lakes and dams. Large distances can be achieved with relative ease. Use of the ‘Fluke Board’ in this manner is an excellent form of exercise and a chance for an adventure! Wearing of a wetsuit or floatation vest is highly recommended for longer distances of travel, for safety in the event of cramps or exhaustion, as the floatation provided by the ‘Fluke Board’, while providing some variable amount of buoyancy, is not sufficient to fully support the weight of the rider.

The ‘Fluke Board’ may be used in the ‘lying prone posture’ for snorkeling, providing forward propulsion in a more relaxed manner than with conventional swimming fins and obviating the need for swimming fins. Conventional swimming fins are relatively clumsy and awkward to use, also causing foot, ankle and leg discomfort and difficulty with balance. These can be avoided by the use of a ‘Fluke Board’, while also providing rest and security of buoyancy to increase viewing pleasure of the snorkeler.

The less buoyant or reduced buoyancy ‘variable buoyancy’ Fluke Board' may be used in the ‘lying prone posture’ for free diving or scuba diving and in the ‘standing/crouching posture’ for scuba diving. The hand held posture would be suitable for altering depth and for exploring and would allow faster travel, while the vertical riding style with said guy rope/s would suit for more horizontal open spaces travel and enjoyment of a more panoramic viewing of the marine environment. Wrist straps may be used to secure the guy ropes, while still allowing the diver use of hands. Admittedly this would be more restrictive of arm use, such as for hunting or spear fishing, than conventional scuba diving using swimming fins as a means of propulsion.

In scuba or free diving, it may suit the diver to use a combination of swimming fins and the ‘Fluke Board’, where the fluke board assists with depth and direction control in the manner of pectoral fins used by a dolphin.

Revisiting the foot housing option would be worth a consideration for use in scuba diving.

Specifications

What does a Rider Require in Order to Use the ‘Fluke Board’?
What are the Features, Variations and Adaptations of the ‘Fluke Board’, which Suit its Novel Functions?

The ‘Fluke Board’ Rider

Mastering the use of the ‘Fluke Board’ requires coordinated rhythmical movements, fitness and balance, especially for use at an increased speed and use in the standing/crouching posture. Older and younger riders may suit the ‘lying prone posture’ which is easier to master and requires less strength and fitness. The ‘Fluke Board’ rider should be competent in the water as some swimming skills may be required.

Novel Features of the ‘Fluke Board’

The ‘Fluke Board’ is buoyant enough to readily float on the surface of the water but not enough to fully support the weight of the rider at standstill and not enough to significantly limit the down-thrusting action of the rider when the ‘Fluke Board’ is in operation. Nevertheless the buoyancy of the ‘Fluke Board’ acts to support the ‘lying prone posture’ rider as a buoyancy aid.

The ‘Fluke Board’ is less buoyant, thinner, sharper-edged and shorter when compared to existing surfboards. The ‘Fluke Board’ is also heavier, size for weight, and generally relatively wide when compared to existing boards.

With these said features the ‘Fluke Board’ is able to cut through the water, being a hydrodynamic foil, where existing surfboards are only designed to float on the surface of the water.

The said specially designed shape and reduced buoyancy, compared to existing boards are the design features which allow for easier pivoting of the ‘Fluke Board’.

A recommended material to manufacture the ‘Fluke Board’ is marine grade hardwood plywood, produced with waterproof glue, sealed with marine grade varnish or resin. Different thicknesses of plywood provide different buoyancy and weights to suit different users and different specialized applications, as discussed above and below under the ‘variations’ section.

Other materials with similarly suitable buoyancy and strength such as fiberglass or hard plastics and resins may be used to produce ‘fluke Boards’ which may be hollowed. Aluminum/alloys and other molded or pressed materials, including stainless steel plate, may also be used. Two separately manufactured halves may be joined to create a cavity for buoyancy. Construction of ‘Fluke Boards’ with these materials may involve use of a core of polystyrene or similar buoyant compound, to control the degree of desired buoyancy while providing a strong, pressure resistant and water resistant core.

With the hard-shelled options, especially the molded aluminum and pressed sheet metals, an internalized sealed space can be created to be filled with air, or water, or a ratio of air and water, with sealable port/s. This then provides the ability to alter/choose the buoyancy to suit the rider's purpose, as discussed in the section on potential uses of the ‘Fluke Board’. There are no other ride-on boards, which utilize this novel technique for adjusting buoyancy.

Variations

Two or more flat or curved, hydrodynamic sheets of thinner marine grade plywood, sealed with marine varnish or similar, or any other waterproof, strong, buoyant material, such as hard plastics or fiberglass, may be joined to form a ‘Fluke Board’ with longitudinally placed channels, support struts, or fins, which channel water internally or over the outer surface, for increased efficiency of forward propulsion. Two simple examples are illustrated.

Graduated sizes and various shapes, colors and surface decorative designs of the ‘fluke Board’ will be made available to suit the different weight, height and strength ranges and also personal preferences and specialized uses of riders, as noted above.

One useful example is ‘scalloping’ of the ‘Fluke Board’ resulting in a shortened central section and expanded lateral foils. This shaping provides improved thrusting potential for the ‘lying prone posture’ rider, as illustrated.

Adaptations

With a suitable amount of buoyancy being vital to the successful operation of the ‘Fluke Board’, a ‘variable buoyancy’ function is a great advantage.

Buoyancy of a ‘Fluke Board’ can be adjusted by formation of a sealable portal to access the internal space of ‘Fluke Boards’ with a hollow foil. Fluid, such as water may then be allowed to flow into the internal space, or out again, to adjust for weight/buoyancy.

The potential for this fluid to slosh around and cause alterations in the balance and function of the ‘Fluke Board’ can be avoided by having two portals connected by a coiled internal hose or channel, in which both portals may be opened for filling or emptying fluid from a centrally placed portal with the additional portal being positioned on the edge of the foil and opened to allow air entry or exit during filling or emptying the fluid. In this way the variable amount of fluid is contained symmetrically so as not to affect the balance and function of the ‘Fluke Board’.

This system for altering buoyancy is not illustrated but is self-explanatory.

The said optional guy ropes provide ‘Fluke Board’ rider grip, stability and maneuverability for the said ‘standing/crouching posture’, while producing minimal drag force. They provide ability to tilt the ‘Fluke Board’, as described. Shorter-styled ‘Fluke Boards’ may use laterally placed guy ropes, which like the handle position, described above, is attached forward of the midline, to match the position of the feet, creating a forwardly placed pivot point to naturally create the forward and backward tilting required for the fluke-like action, as described above. See illustration.

An optional addition to the ‘Fluke Board’ is the ‘Tube Fin’. The ‘Tube Fin’ is made of PVC pipe, or suitable alternative material tubing, which is attached, bilaterally, to the ‘Fluke board’. Different attachment methods can be used. See illustrated example.

The ‘Tube Fin’ provides increased speed and efficient operation of the ‘Fluke Board’ by reducing the tendency for water to flow off laterally from the ‘Fluke Board’ in operation. There is also the formation of two columns of water, which flow backwards through the tubes to be ejected against surrounding water, like jets, to help with forward propulsion of the ‘Fluke Board’.

The ‘Tube Fin’, like other fins, also resists rotation of the ‘Fluke Board’ in operation, which entrains a forward direction of travel.

For the narrower ‘Tube Fins’, which are not as efficient as wider tubes, the rider's fingers and thumbs encircle the pipe, increasing grip power.

Larger diameter tubing requires another style of handle, as illustrated.

A further optional but recommended addition is the laterally placed ‘Side Fins’. These are planar hydrodynamic contoured foils, attached longitudinally, in the vertical plane, to the sides of the ‘Fluke Board’. They offer the advantage of allowing a funneling of water flow over the driving face of the foil of the ‘Fluke Board’ and preventing flow in a lateral vector. This results in increased efficiency of forward propulsion, with a more directed route of travel.

Handles may be formed on the ‘Side Fins’ at a position that is elevated above the foil of the ‘Fluke Board’. This allows marginally more thrusting distance from the position of full arm extension to the position of full flexion, to improve efficiency of forward propulsion.

Elevating the position of the handles results in the disadvantage of movement of the pivot line above the foil. This causes swinging of the ‘Fluke Board’ backwards and forwards, rather than remaining in the same line of thrust when the pivot line is on the foil. This swinging effect increases the difficulty of maintaining a rhythmical thrusting action and an efficient forward propulsion, negating the advantage of a longer thrust.

The strength of attachment of ‘Side Fins’ is enhanced by the use of low profile, or embedded, corner brackets or dowel. See illustration.

Alternatively, the attachment of ‘Side Fins’ may be aided by creating slots in either the fin or the main body of the ‘Fluke Board’. The two structures may then be joined and attached by glue and reinforced with corner dowel or brackets.

Finally, ‘Channel Fins’ may be added to a ‘Fluke Board’. ‘Channel Fins’ are placed medial to ‘Side Fins’ to create channels. These channels are useful for ‘Fluke Boards’ with an abbreviated, or scalloped central connecting section with bilaterally expanded sections of foil, which are designed to suit the ‘lying prone posture’ use. See illustrations.

Further Comparisons with Existing Boards

A heavier weight/density of a ‘Fluke Board’ in comparison to existing surfboards is not a disadvantage for the rider and is a function of the ‘Fluke Board's’ mode of action, being designed for use (mainly) under water. The ‘Fluke Board's’ weight is more than supported in the water by its own buoyancy. Forward momentum of the ‘Fluke Board’ is increased with a heavier mass, making for a steadier ride.

While in the standing posture, unless riding a wave, the main drag force negating the forward momentum of the ‘Fluke Board’ and rider, are the legs and feet of the rider, akin to wading, unlike existing surfboards and paddleboards, which only float and have no associated leg drag force.

While using the ‘Fluke Board’ in the ‘lying prone posture’ there is significant drag force, akin to swimming. This enables the enjoyment of moving through water, rather than floating on it as with other boards, suiting snorkeling when operating the ‘Fluke Board’ gently and suiting diving.

Cutting under oncoming waves on the ‘Fluke Board’ is efficient and safe with its said hydrodynamic contour and less buoyancy. This provides an advantage over existing surfboards.

The ‘Fluke Board’ is equally at home deep under water, performing its hydrofoil action effectively to aid the scuba diver, either in the ‘lying prone posture’ or the ‘standing/crouching posture style of use.

DESCRIPTION OF DRAWINGS

FIG. 1.

Frontal, aerial, oblique view of a suggested shape of a ‘Fluke Board’, which is suited to the ‘lying prone posture’, is depicted. Note the shorter style.

The optional addition of ‘Side Fins’, attached to the edges of the foil, is also depicted.

Note the handles incorporated into the front half of the upper ‘Side Fin’.

Note the side-by-side foot grips for the crouching posture in wave riding.

FIG. 2.

The profile view of a typical ‘Fluke Board’ foil, which best demonstrates its hydrodynamic contour. ‘Side Fins’ are included, with handle grips incorporated.

FIG. 3.

Aerial oblique view of a ‘Fluke Board’ with rubber foot grip pads for improved footing.

An alternative to this, not shown, would be shallow indentations for the feet.

Elastic rubber guy ropes with suggested attachment technique and wrist straps are also depicted.

This larger styled ‘Fluke Board’, with increased buoyancy, is best suited to surfing and the ‘standing/crouching posture’ use.

FIGS. 4A and 4B.

Aerial and frontal views, depicting two examples of double-foiled ‘Fluke Boards’.

Internal water channels are depicted, along with scoop-shaped external foil surfaces with fin-like formations and struts, for increased volume of water entrainment and directional control.

Note in 4B that the lower scoop-shaped foil is smaller, which creates less drive force, suited to the ‘lying prone posture’ rider wearing floatation clothing, to improve the rider's ability to maintain a rhythmical and coordinated fluking action. It exemplifies design variations to suit different purposes.

FIG. 5.

Depicting oblique views of a further suggested shape of ‘Fluke Board’.

Note scalloped central isthmus, which enables longer unobstructed thrusting action, suited, but not exclusive, to the ‘lying prone posture’ use.

This example illustrates the use of ‘Side Fins’, which are attached by slotting into the main body of the ‘Fluke Board’, reinforced by corner brackets. The hydrodynamic contouring of both the fins and the main body are not detailed in this drawing.

FIG. 6

‘Channel Fins’ are shown, which when combined with the ‘Side Fins’, create longitudinal channels for a greater volume of water entrainment for more efficient forward propulsion.

Side to side balance/stability is improved with this wider shaped ‘Fluke Board’.

FIG. 7.

Depicting a view of a ‘Fluke Board’ using ‘Tube Fins’.

Claims

1. A hydrodynamic foil structure, dubbed the ‘Fluke Board’; constructed from plywood with waterproof sealant, or hollowed cast/molded materials, such as resin, plastic, aluminum/alloy; or pressed sheet metal, or other suitably strong, durable and waterproof material; with or without polystyrene, or similar, core; buoyant but submergible in water by a rider who exerts piston-like cyclical thrusts with hands or feet, at a forwardly placed pivot point; said foil structure alternately inclined about the vector of travel during each thrusting action, as dictated by the said forwardly placed thrusting contact/pivot line; so as to cause the ‘Fluke Board’ to exert frictional force against adjacent water in a vector opposite to the direction of travel and perpendicular to said thrusting vector, in the manner of a fluke.

2. A ‘Fluke Board’ as in 1, with a single, contoured, planar, hydrodynamic foil, with a scalloped forward and/or aft central section, as discussed and examples illustrated.

3. An adjustable buoyancy ‘Fluke Board’, as in 1 and 2, with a hollow internal space, accessible via sealable portal/s, for selective influx or efflux of fluid.

4. A ‘Fluke Board’, as in 1, 2 and 3, constructed by connecting two or more, planar or curved, buoyant, hydrodynamic foils, to form one or more, internal or external, longitudinally aligned channels/struts/fins, as illustrated.

5. A ‘Fluke Board’, as in 1, 2 and 3, with ‘Side Fins’ attached to both sides, as described and illustrated with simple examples.

6. A ‘Fluke Board’ as in 5, with bilateral ‘Channel Fins’, medial and parallel to the ‘Side Fins’, as described and illustrated.

7. A ‘Fluke Board’, as in 1, 2 and 3, with the addition of ‘Tube Fins’ as described and illustrated.

8. A ‘Fluke Board’, as in 1, 2, 3, 4, 5, 6 and 7, with forwardly placed hand grips/handles, as illustrated.

9. A ‘Fluke Board’ as in 1, 2, 3, 4, 5, 6, 7 and 8, with the addition of a guy rope/s, attached centrally to the front and rear of the ‘Fluke Board’, or bilaterally at a forwardly placed pivot line, with free ends suitably adapted to be hand-held, or attached/strapped to wrists, forearms or shoulders, for use in the ‘standing/crouching posture’, as described and illustrated.

10. A ‘Fluke Board’ as in 9, adapted by size, shape and buoyancy, for surfing, with novel means of propulsion to catch a wave, novel improved ability of the ‘Fluke Board’ to cut through oncoming waves, and novel ability of the rider to be secured to the ‘fluke Board’ while surfing, with said guy ropes or handles, as described.