Hydrofoil Configurations - What Can they Do for You?
A Boat Hydrofoil is an accessory for an outboard motor that is used to decrease the drag on the hull and to help increase the overall speed of the boat. Hydrofoils are usually mounted on the bow blades or the stern as well as the outboard motor mount. The concept is that the foil increases the overall flow through the boat's transom and decreases the resistance from the surface of the water. This, in turn, reduces the drag and allows for a faster speed to be achieved. There are many different types of these, but mainly they are manufactured with either Teflon or stainless steel foils.
Typically, if you have an outboard motor and wish to use this type of hydrofoil, then the boat's bow hydrofoil should be mounted above the outboard motor mount, preferably at the same height as the main mast. The lower mounting point will allow for the foil to operate more efficiently. Typically, the foil is between twelve and twenty-four inches in length. On larger boats, such as sail boats and powerboats, they may be required to be further measured to fit at specific depths.
These types of foils come in a variety of colors and designs as well as shapes and sizes. The most common types of boat foils that are used are flat, triangular, V-shaped and diamond square foils. The diamond square is the most efficient, but is also the hardest to manufacture. All other types of foils are manufactured with various thicknesses and heights, but are also made of different metals.
The diamond shape is used primarily to reduce the surface tension between the foil and the transom. In comparison to the flat and triangular foils, the triangular design requires the most cutting which also causes it to be the heaviest. The diamond hydrofoil boat design does not require much pressure in order to create the optimum triangular shape. The diamond shape is also called the perfect hydrofoil boat shape by many designers.
With boats being rowed, rolled, or swept, the hydrofoil design increases the overall efficiency of the boat. For example, with an outboard motor, each stroke of the paddle moves two gallons per minute. If the boats were rowed, then the number of strokes would increase approximately four times the rate of the motor. The hydrofoil design reduces this variation and is therefore much more economical.
In smaller vessels, the hydrofoil works well with the concept of the hydrodynamic plan. This is where the boat is laid on its side and the stern foil is laid across the bow and stern. The boat is then propped up with the transom above water level and the back end of the hydrofoil is laid along the tail's trailing edge. This arrangement is referred to as a forward mounted hydrofoil. The hydrofoil acts to deflect the waves that result from a wake that is created by the wakes created by the engine. The deflecting surface moves with the boat thus minimizing the wave effect.
Boat designers often use a combination of both the above designs. For example, many small sailing dinghies are designed with a forward mounted hydrofoil. On the other hand, larger boats often have a set of rear foils that are used to deflect the wakes created by the inboard motor. The rear foils are usually placed a little further out than the forward foils so that they do not interfere with the movement of the main body of the boat. This type of combination of inboard and hydrofoil is often referred to as a "superior" design.
Boat owners looking for unique boat features will often choose hydrofoil configurations that are different from conventional designs. For example, some of these boats use long bolts that penetrate through the bow foil to attach to the hydrofoil. While this does add additional weight to the boat, it also adds strength to the bowsprit (a stronger part of the boat that runs from the stern to the transom). These long bolts are also great at keeping wind, rain, and other unwelcome elements from affecting your boat. It should be kept in mind that you must remove the long bolts before adding them to the bow foil as this creates a safety hazard.