A pulley with one or more sheaves (grooves), over which a rope is roved. It can be used to chage the direction of the rope, or in pairs used to form a tackle.



Related Terms

PENDANT

  1. A length of wire or rope secured at one end to a mast or spar and having a block or other fitting at the lower end.
  2. A length of wire or rope hooked to a tackle on leeboards.
  3. A long, thin triangular flag flown from the masthead of a military ship (as opposed to a burgee, the flags thus flown on yachts).

UNREEVE

To pull a rope from a sheave or block.

END FOR END

To reeve a rope in the opposite direction through a tackle in order to put an unworn section over the pulley.

SHEAVE

Pulley in the block

LIFT

1) A change in wind direction enabling a yacht to point in a direction that was previously too close hauled. 2) A rope or tackle from a boom to the mast to support and move it for cargo working.

SNATCH BLOCK

A single sheave made so that the shell opens on one side of the base allowing a rope to be slipped over the sheave without threading it. Used to change direction of pull.

PELORUS CARD

The part of a pelorus on which the direction graduations are placed. It is usually in the form of a thin disk or annulus graduated in degrees, clockwise, from 0° at the reference direction to 360°.

CB

Block coefficient - a measure of the fullness of the form of the ship and is the ratio of the volume of displacement to a given water-line, and the volume of the circumscribing solid of constant rectangular cross-section having the same length, breadth and draught as the ship. CB= (L x B x T) The LPP is normally used in calculating the value of CB which varies with the type of ship. Fast ships Ordinary ships Slow ships 0.50-0.65 (fine form) 0.65-0.75 (moderate form) 0.75-0.85 (full form)

CHAIN FALL

A tackle which uses an endless chain rather than a rope, often operated chain belt mit power. chain block from an overhead track to lift heavy weights especially in workshops.

SPLICE

To join lines (ropes, cables, etc.) by unravelling their ends and intertwining them to form a continuous line. To form an eye or a knot by splicing.

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