Parameter rope (called a stay or sheet) which holds the lower side or corner of a sail to the deck of a boat; in the case of the mainsail, it is attached to the boom; in the case of the spinnaker, it is attached to the corner closest to the mast; it acts as a gear controlling the direction of boat sailed into wind or wave [558b5c1c8edb0b4c17cc8d848ef8d0f4]