Design of the Wow!10

The Wow!10's design goal is to provide a single-handed, high performance dinghy which is fast yet stable, light yet rugged, appropriate for racers yet fun and safe for kids, and suitable for all weather conditions, sea states and bodies of water.  These may seem like mutually exclusive goals, but are attained by making careful decisions at the extremes of the performance ranges.

Design decisions and goals:

Length at deck: 10.1 ft.  The 10 foot length is chosen because windsurfers, SUP's and sailboats for kids are about this length.  One goal is to provide a boat which is easily transported on the top of a car.  Also one of the Wow10!'s aims is to offer an athletic experience to the sailor.  The theoretical "critical speed" determined by the length of a sailboat is low for boat this short, but this is countered by the narrow beam at the waterline and the planing bottom of the hull.

Sail area: 97 sq. feet, 9 sq. meters.  This is the same area of the 9 option for the RS Aero® even though the Aero® hull is longer by about 3 feet.  Heeling control is implemented by hydrofoils mounted on the starboard and port gunwales so an even larger sail area can be utilized. The high speed of the Wow!10 is due to the large sail area and is particularly noticeable in light winds when the hydrofoils are retracted during reaches and runs and thus do not produce drag.  

The fundamental concept on sail area is that as sail area increases, as long as the increased driving force produced by the sail exceeds the increased drag produced by the hydrofoils, speed will also increase.  Since to a first approximation driving force increases with sail area and drag increases as the square of speed, a doubling of sail area will increase speed by about 40%, if all other characteristics are the same.  

Mast and boom lengths:  The mast and boom lengths are the same as for the RS Aero® and the same sails can be used.

Hydrofoils:  There are three hydrofoils, one on each gunwale and one on the rudder.  This provides three point suspension stability.  The attack angles of the ones on the sides can be adjust up to stall angle positively and negatively, and their immersions can be varied from totally retracted to maximally immersed.  The foil on the rudder can be adjust for positive attack angles up to the stall angle, and it can be rotated 180º vertically for beaching.  The struts on the side foils extend below the foils to the level of the bottom of the boat so even when fully retracted, they provide some leeway control but produce minimal drag.

Automatic Hydrofoil Adjustment:  When a boat tacks, the skipper must operate the tiller, re-trim the sail and switch his/her body from one side to the other.  However, the hydrofoils must be re-adjusted in both attack angle and depth of immersion.  These requirements compound the activities needed during tacking so automatic adjustments are desirable. Two major modes of adjustment are available - manual and automatic.  Three different manual adjustments can be made - immersion depth , single foil attack angle determination and dual or single foil usage.  

The hydrofoil strut holders are designed so the struts slide freely up and down.  

Heel Angle Compensation: The hydrofoils are in the shape of a "V".  The angles of the legs of the V are +20º for the starboard-most leg and +160º for the port-most leg.  The boat is designed so that it performs best at heels between -20º and +20º.  As a result, the leeward outermost leg of the V is most effective at a heel angle of 20º , and the innermost windward leg of the V is also at its most effective angle.  Thus unlike many foiling boats, the Wow!10 performs best with a small heel.

Since the inward facing legs of the two V's aim up slightly toward the center of the boat, the bottoms of the gunwales at canted at 20º so the hydrofoils nest against the bottom the gunwale when retracted.  This results in the beam at the deck being much larger than the beam at the water line.

Enhanced Hiking:  Fat gunwales are used so that when the boat is heeling, the length of the righting lever arm due to hiking is long.

Transportation Features:  To avoid the need for a dolly when the boat is transported at the beach, the hydrofoil assemblies can be removed and replace by wheel assemblies.  Also hulls can be nested close together when fleets are transported.  There is no daggerboard well, and the brackets which hold the mast and rudder assemblies can be detached.