How to Hook Up Tackle

There's no need for trial and error in learning to rig tackle.

You have two blocks with two pulleys in each, one coil of line, and instructions to turn them into something called a "gun tackle." You know that "tackle" has something to do with "block and tackle," but beyond that, you're lost. Whether you're controlling a sail or moving machinery across the deck, knowing how to rig tackle is an essential "sailor skill."

Instructions

1. Lay both blocks down so one is on its side and the other is standing on edge. The hooks on the blocks should point in opposite directions.

2. Run the line through a pulley in one of the blocks. The first block you put rope through is the head block that is anchored in place to support and control the movement of the other block in the block and tackle.

3. Pull the rope through one of the pulleys on the other block. The second block you reeve---the technical term for threading rope through a block's pulleys---is the heel block. It's attached to the object you want to move, lift or control.

4. Carry the line from the heel block to the head block. Reeve the rope through the empty sheave---the technical term for a pulley in a block---in the head block.

5. Pull the line back to the heel block. Reeve the rope through the empty sheave in the heel block, then pull the line back up to the ring on the bottom of the head block. Tie the rope through this ring, or thimble, with a stout knot.

Tips & Warnings

• Rope is line that's riven over a pulley. When not inside the block, in contact with the pulley, it's called line.

• Pick blocks based on the size of the line and the size of the block's "cheek," or side plate. Fiber line (nylon, polypropylene) needs a block with a cheek three times the size of the line. For example, a 1 1/2-inch nylon rope requires a block with at least a 4 1/2-inch cheek (3 x 1 1/2 = 4 1/2). Blocks come in even sizes only, so round the size up to 5 inches.

• Wire rope requires a block with a cheek at least six times the size of the wire rope. A 1/2-inch wire rope needs a 3-inch block: 6 x 1/2 = 3.

• Tackle riven through blocks that are too small is prone to failure. The rope may burst with dire consequences.

References

• Global Security: FM 55-501, Chapter 20, Section 1, Blocks and Tackles