Mechanical advantage force applied at "A" the end of the rope, and let "F" be the force at "B" on the moving block. Like the velocities "F" is directed downwards and "F" is directed upwards. For an ideal block and tackle system there is no friction in the pulleys and no deflection or wear in the rope, which means the power input by the applied force "F""V" must equal the power out acting on the load "F""V", that is The ratio of the output force to the input force is the mechanical advantage of an ideal gun tackle system, This analysis generalizes
Block (sailing) matter is slightly complicated by the fact that every tackle has a "working end" where the final run of rope leaves the last sheave. More mechanical advantage can be obtained if this end is attached to the moving load rather than the fixed end of the tackle. There are various types of blocks that are used in sailing. Some blocks are used to increase mechanical advantage and others are used simply to change the direction of a line. A "ratchet block" turns freely when a line is pulled in one direction but does not turn the other direction, although the