Ice Boat - Modern Designs

Modern Designs

Modern iceboats designs are generally supported by three skate blades called "runners" supporting a triangular or cross-shaped frame with the steering runner in front. Runners are made of iron or steel and sharpened to a fine edge, most often cut to an angled edge of 90 degrees, which holds onto the ice, preventing slippage sideways from the lateral force of the wind developed by the sails. Once the lateral force has been effectively countered by the runner edge, the remaining force of "sail-lift" vacuums the boat forward with significant power. That power increases as the speed of the boat increases, allowing the boat to go much faster than the wind. The only seeming limitations to iceboat speed are windage, friction, the camber of the sail shape, strength of construction, quality of the ice surface and the level of skill, athleticism and fearlessness of the sailor. Iceboats can sail as close as 7 degrees off the apparent wind.

Modern designs of iceboats are very efficient, utilizing aerodynamic designs and low friction, and can achieve speeds as high as ten times the wind speed in good conditions. International DN iceboats often achieve speeds of 48 knots (89 km/h; 55 mph) while racing, and speeds as high as 59 knots (109 km/h; 68 mph) have been recorded. Skeeters and older large stern-steerer iceboats can exceed 90 knots (170 km/h; 100 mph). The rumored, but unconfirmed, top speed of an iceboat is over 130 knots (240 km/h; 150 mph). One reference to a timed run on Lake Geneva, Wisconsin reported an "E-Skeeter" as having reached 137 knots (254 km/h; 158 mph). The same reference reported clocking a DN 60 iceboat on a closed course over black ice on Green Bay, Wisconsin at 94 knots (174 km/h; 108 mph). The stern-steerer Debutaunte, recently rebuilt, was timed over a measured mile at 124 knots (230 km/h; 143 mph) on the ice of Lake Winnebago, Wisconsin in 1938.

Because of the very high potential boat speeds, iceboat race courses are established around fixed marks which are to be rounded in a one-way route. The courses are deliberately set in a straight line upwind and downwind, though the boats have to tack back and forth to advance through the course. This course configuration provides a measure of traffic safety between competitors. Also, by directing the iceboat straight upwind or straight downwind, the sailor can best control and prevent the sail from generating excessive horsepower, resulting in the slowest directions of travel. Recorded racing speeds for an International DN in 9 knots (17 km/h; 10 mph) winds are 26 knots (48 km/h; 30 mph) upwind, and 35 knots (65 km/h; 40 mph) downwind. A downwind speed of 49 knots (91 km/h; 56 mph) was recorded at a World Championship in winds of just 13 to 15 knots (24 to 28 km/h; 15 to 17 mph).

Iceboats are not produced commercially on a wide scale, but remain largely the province of hobbyists and enthusiasts building with high quality wood and plywood and more exotic materials such as foam, carbon fiber, fiberglass and epoxy. There are no known governmental licensing or registration requirements. Several classes are organized and boats must conform to the designs and rules of the classes in order to race.