Im re reading john lechters book on self steering and he talks of "a fools purchase" for eg " a fools purchase was required to dovide sheet tension by 2" im thinking its a knot ??
the term is used to describe a reversed block-and-tackle arrangement. on a sailing boat most tackles are setup to generate more force. if you reverse the tackle arrangement you generate a fraction of the applied force instead.
reversing a basic 2:1 tackle arrangement would give you half the tension (and twice the motion)...
