Parts Of A Block

A. Eye
B. Crown
C. Swallow
D. Sheave
E. Tail
F. Becket
G. Cheek
H. Pin/Tally Plate (pin underneath plate)

A block  is a portable pulley, made of wood and/or metal.
Originally it was a block of wood with a hole in it for a rope to reeve through. Over time the idea was improved upon until we have what we see today.

Parts Of A Tackle

Standing block - the block that is anchored and not moving, it changes the direction of the running part.

Moving block - the block attached to the moving end (load end).

Standing part - this part does not move. It needs to be secured to either the standing block or another fixed position.

Running part - the rope between the two blocks that pulls the running block along the standing part.

Hauling part - the part that is pulled

Fall - the rope rove through the block.

A purchase is a mechanical device by means of which a pull or force is increased.

A  tackle (pronounced taycle) is a portable purchase consisting of a rope rove through two or more blocks in such a way that any pull applied to its hauling part is increased.

The amount of increase depends on how many sheaves there are in the blocks, i.e. a single, double or triple block and the manner in which the rope is rove through them.

The amount by which the pull on the hauling part is multiplied by the tackle is called its mechanical advantage It is roughly equal to the number of parts of the fall at the moving block.eg in the example shown there are 2 falls, the standing and falling parts. Each applies a mechanical force to the load so therefore the mechanical advantage of this tackle is 2. The hauling part is not counted as it comes from the standing block not the moving block

The blocks of a tackle are called the standing block and moving block, and the rope rove through them is called the fall.

These tackles use only single blocks

The Luff uses a single at the bottom and a double at the top.(Mech advantage=3)
The Two Fold Purchase uses two doubles and the Three Fold uses triple blocks
What is the mechanical advantage of them?

Mousing a hook

When using a tackle hook it is sometimes necessary to mouse (pronounced mouze) the hook.

Mousing a hook is used to prevent a hook from unhooking from the strop or to prevent a strop from jerking out of the hook.

A mouse is put on with whipping twine.

How to mouse a hook

1. Using a piece of twine about 40-50 cm long. Fold the twine in half. Slip the twine over the hook. Wrap the twine as shown. Wrap at least two or three turns with both parts of the twine. Ensuring that the twine is pulled tight. If a large hook is used, more twine will be required.
2. Take one part up and around the turns several times. Take the other part around the bill.
3. Bring the two ends together and finish off with a reef knot.