A gyn is a form of three legged lifting device used on
sailboats. It provides more stability than a derrickor sheers, and requires no riggingfor support. However, it can only be used for lifting things directly up and down. Gyns may also be used to support either end of a ropeway. [cite book|title=Admiralty Manual of Seamanship|author=Ministry of Defence (Navy)|date=1995|publisher=The Stationery Office|id=ISBN 0117726966|pages=3-195–3-196]
Two legs, called cheeks, are bound together as in the sheerlegs. The third spar is called the prypole and is fixed under the cheeks. Only four pulleys are required; three as splay tackles and the fourth one as lifting purchase. A
timber hitchof six figure-of-eight turns and a finishing clove hitch lash the crutch but not too tight because the cheeks need some room to spread their heels. The cheeks of the gyn are now ready to spread and to be erected, the cheek splay tackle is hauled tight and then the other adjacent splay tackles can be lashed. At the sides, the gyn is unstable and it is crucial that the cargo is not swung out of the base triangle; consequently the gyn is only for lifting cargo vertically. [cite book|title=The Theory and Practice of Seamanship|author=Graham Danton|date=1996|publisher=Routledge|id=ISBN 0415153727]
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