Sheathing. A casing or covering on a vessel's bottom.

Shears. Two or more spars, raised at angles and lashed together near their upper ends, used for taking in masts. (See page 52.)

Shear Hulk. An old vessel fitted with shears, &c., and used for taking out and putting in the masts of other vessels.

Sheave. The wheel in a block upon which the rope works.

Sheave-hole, the place cut in a block for the ropes to reeve through.

Sheep-shank. A kind of hitch or bend, used to shorten a rope temporarily. (See Plate 5 and page 50.)

Sheer, or Sheer-strake. The line of plank on a vessel's side, running fore-and-aft under the gunwale. Also, a vessel's position when riding by a single anchor.

Sheet. A rope used in setting a sail, to keep the clew down to its place. With square sails, the sheets run through each yard-arm. With boom sails, they haul the boom over one way and another. They keep down the inner clew of a studdingsail and the after clew of a jib. (See Home.)

Sheet Anchor. A vessel's largest anchor: not carried at the bow.

Shell. The case of a block.