Page 11 - Mario Bigon "The Morrow Guide to Knots"

Natural fibers

Natural fibers have now almost completely been replaced by
synthetics, but the most commonly used were hemp, manilla,
cotton, and sisal. It is still possible to come across rope made
of hemp, which up to a few years ago was the best material
available for rope. The advantages of this material are its
tensile strength and an excellent resistance to wear and
atmospheric agents, which is even better than that of
synthetic fibers. Its disadvantages are that it is heavy
(especially when wet) and is not very elastic, but particularly
that it rots easily and has to be stored carefully.

Synthetic fibers
As their name suggests, these fibers are compounded by man
from oil or coal derivatives. They are all shiny, non-absorbent,
do not rot, and have low melting points. The production
processes involved make it possible to improve features such
as the fineness, strength, and elasticity. In general, an increase
in the strength of a rope corresponds with a decrease in its
flexibility. Greater fineness is associated with greater strength
and flexibility but also with less abrasion resistance. The most
common fibers are polypropylene, polyamide, and polyester,
but to complete the picture, we have also included
polyethylene and aramid.

Polypropylene fibers
(commonly known as olefin)
These are widely used in commercial sailing, as they combine
low cost with excellent mechanical qualities and abrasion
resistance. They also have very high resistance to atmospheric
agents, light. and the hydrocarbons that are always present on
the surfaces of commercial ports. This is the only fiber that
floats well, so it is most suitable for use in water skiing tow
ropes, rescue lines, and for mooring large ships. It is not
commonly used in competitive sailing, possibly because it is
cheaper than other types of rope.

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