• It stretches very little and for this reason
is commonly used for halyards and other
sailboat rigging, towing line, and applications
where you do not want stretch to
interfere.
• It will chafe easily so check it often and
protect as necessary.
Polypropylene
Polypropylene rope is light and is the least
costly of the synthetic ropes.
• It lacks the strength of nylon or polyester
and is slippery, which increases the
chance that a knot will not hold.
• Compared to the other types of rope,
polypropylene deteriorates more rapidly
in sunlight.
• Its fibers tend to fray and break, and the
rope will break under high stress.
• A useful characteristic of polypropylene is
that it floats. This reduces the risk of getting
the line wrapped around a propeller,
making it ideal for towing dinghies and
water-skiers.
• It is not a good line for dock lines because
its hard surface tends to slip from cleats,
and it can cause cuts if it runs free
through your hands.
Types of Weave
Rope is woven in two forms.
• Three strand—laid rope—has tiers
of fibers that are twisted in groups of
three, usually in a clockwise direction;
then those twisted fibers are themselves
twisted in groups of three, and so on until
the rope is built up to its final size (Figure
16-1). Laid rope is usually economical
and is strong, but tends to be rough in the
hands.
• Braided—The fibers are interwoven in
clockwise and counterclockwise directions
along the length of the rope (Figure
Section 16: Knots and Lines 177
16-2). Braided rope generally has two
parts, a hard strong core and one or more
braided layers.
• Braided rope is flexible and smooth in the
hands and less likely to fray on smooth
surfaces, but it is more expensive than
three-strand line and has a tendency to
snag on pilings and rough surfaces.
THE CLEAT HITCH
This is the simplest and most important
hitch used on a boat. It involves nothing
more than making a few turns of the line
around the horns of a cleat. (A cleat is a
fitting with two projecting horns to which
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Figure 16-1. Three-strand laid line
Figure 16-2. Braided line