Block and tackle systems. A block is a set of pulleys or sheaves mounted on a single frame. An assembly of blocks with a rope threaded through the pulleys is called tackle. A block and tackle system amplifies the tension force in the rope to lift heavy loads. They are common on boats and sailing ships, where tasks are often performed manually. In the diagram shown here, the number of rope sections of the tackles shown is as follows: Note that the gun tackle, double tackle and threefold purchase all have the same number of pulleys in both blocks (one, two and three,
Miztec (schooner barge) the State of Michigan after they were seized in a 1992 Michigan Department of Natural Resources and Environment (DNRE) raid on the Great Lakes Shipwreck Museum. The State allows the museum to hold a triple sheave block and hook and a double sheave block and hook from the "Miztec" as a loan. Her wreck is now protected by the Whitefish Point Underwater Preserve as part of an underwater museum. The 194 foot wooden "Miztec" was built as a 3-masted schooner in 1890 in Marine City, Michigan. She was enrolled at Port Huron, Michigan on 8 April 1890. On 3 May