ROPE AND ITS PRESERVATION 611
and a loose plate or cover Z) rests on top of the sheave, with wood
ring E between them. This cover is prevented from turning by pins.
A hand wheel engages with a screw operating a spring ; by turn-
ing this wheel the grooved pulley is compressed against the wood
and retarded or released at will
As the rudder moves, the sheave revolves, and by simply turning
the hand wheel any desired resistance can be applied, this depending
on the state of the weather ; you simply screw down little by little,
till the gear stops kicking, and as the weather moderates ease up to
suit. In fine weather the sheave runs freewheel, or the wire may be
taken off. In the event of a steering chain carrying away, the
quadrant may be held in position by screwing the brake hard down
until the hand gear is connected or the chain repaired or replaced.
ROPE.
Hope is made of manilla, sisal, hemp or cpir fibres twisted into
yarns, the yarns into strands, and three strands, sometimes four,
are laid up together to form a rope.
Manilla is glossy, smooth, and pliable and good,
Sisal is stiff, harsh, short fibre and not so good. A proportion
of both manilla and sisal is frequently worked into one rope.
Hemp is the best fibre, of great strength and durability, flexible
when wet and wears to the last rope yarn.
V
Boltrope is tarred hemp used for sewing round sails to strengthen
the head, foot and leech, also for lanyard rigging.
Coir is made from cocoanut husk fibre ; it is reddish in colour,
light in weight, about half the strength of manilla, stretches before
parting, and is often used for mooring alongside a wharf where a
ground swell is making a ship range heavily. Coir does not absorb
water, is buoyant, and therefore handy for harbour work when
running hauling lines by boat across a dock.
Hawsers.—Any rope over 5 inches may be ca3ed a warp or
hawser.
Small Stuff.—Marline is two yarns of tarred hemp spun to-
gether ; housline is three yarns, and both are used for worming and
serving ropes and for seizings. Spunyarn is softer, made of two or
three coarse yarns and is used for serving and general work on
board ship,