Forces on sails apart, which generally prevents heeling. Each sailing craft is a system that mobilizes wind force through its sails—supported by spars and rigging—which provide motive power and reactive force from the underbody of a sailboat—including the keel, centerboard, rudder or other underwater foils—or the running gear of an ice boat or land craft, which allows it to be kept on a course. Without the ability to mobilize reactive forces in directions different from the wind direction, a craft would simply be adrift before the wind. Accordingly, motive and heeling forces on sailing craft are either "components of" or "reactions to" the
North Sails to designing sails, with the goal of building sails that were faster than the competition’s. North began testing the strength and stretch characteristics of sailcloth he received from his suppliers, to eliminate variability in his raw materials. He introduced computer-driven cloth cutting machines, to increase the consistency and repeatability of a sail design. North was a pioneer in computer modelling of sail forces and structural loads. North used a laminated Mylar and Dacron sail on the 12-metre "Enterprise" in 1977. North’s emphasis on computer technologies and new materials is reflected in the company today, which makes intensive use of computer