Block and tackle metres per second. Therefore, the mechanical advantage of a double tackle is 4. The mechanical advantage of any tackle can be increased by interchanging the fixed and moving blocks so the rope is attached to the moving block and the rope is pulled in the direction of the lifted load. In this case the block and tackle is said to be "rove to advantage." Diagram 3 shows three rope parts supporting the load "W", which means the tension in the rope is "W/3". Thus, the mechanical advantage is three-to-one. By adding a pulley to the fixed block of a gun
Grappling hook Grappling hook A grappling hook or grapnel is a device with multiple hooks (known as "claws" or "flukes"), attached to a rope; it is thrown, dropped, sunk, projected, or fastened directly by hand to where at least one hook may catch and hold. Generally, grappling hooks are used to temporarily secure one end of a rope. They may also be used to dredge for submerged objects. Historically, grappling hooks were used in naval warfare to catch ship rigging so that it could be boarded. A common design has a central shaft with a hole ("eye") at the shaft base to