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
Polytarp sails Polytarp sails Polytarp sails refer to sails constructed from rectangular polyethylene tarpaulins. Home boat builders often favor these synthetic "sheet" sails because the materials are inexpensive and easy to assemble into functional, durable sails. The usual construction method involves The sail can be strengthened by adding reinforcing material to the corners and stitching around the edges of the sail. Adding grommets to the corners and edges will allow the sail to be attached to the mast and spars. Because these grommets are placed through doubled material and behind the reinforcing line inside the sail edge, the resulting attachment points have