Purchases: Using the principles of blocks (the technical term for pulley) and tackle to create mechanical advantage. In the photo, a simple 2:1 purchase is attached to a 6:1 purchase creating a 12:1 purchase. This means that a user will pull 12’ of line through point C in order to move point A 1 foot and will have an equal reduction in strength needed. If the load on point A is 120lbs, a person only has to pull with 10lbs of effort at point C.
Blocks: Blocks come in many different configurations. The center that rotates is called the Sheave. Some blocks have 2 or 3 sheaves. Some attach with a shackle. Some attach with rope. Some bolt to the deck on their sides. Blocks are used to create purchase and to redirect lines in the boat
Winches: Ratcheting drums for putting serious load on lines, winches are very strongly mounted to the boat and have a series of gears inside. Lines are wrapped around the winch, a handle is inserted and the winch is cranked, then the load either stays on the winch or a clutch or jammer forward of the winch is engaged, the load is eased off the winch and transferred to the clutch and the winch is available for other uses. Most boats have winches for halyards and for jib sheets.