Page 106 - Mario Bigon "The Morrow Guide to Knots"

shortenings

When a rope is too long, shortenings are used to avoid cutting
the rope and losing a lot of its value; as no knot uniting two
ropes can have the same strength as an unbroken cord.
Shortenings also eliminate any worn or damaged sections of
rope; such weakened portions do not take any strain when
they are incorporated into this kind of knot.
Shortenings can be used in many different circumstances,
e.g., for hauling boats, loading goods, putting a rope under
strain, salvaging damaged rope, and towing vehicles. They are
also used, as suggested by their name, for varying the length
of a rope to suit immediate requirements. The main shorten-
ings are: the sheepshank, which is the most important in
sailing; the loop knot, used by truck drivers, and the knotted
sheepshank.

The illustration on the following page shows:
1. Loop knot 2. Sheepshank 3. Knotted sheepshank
1m