Page 142 - The New Encyclopedia of Knots
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unsuitable for sheets and halyards.
The rope will become hard in excessive sunlight, and cannot resist acid attack, although it stands up
to alkalis; see also microfilament, polyester, polyethylene and polypropylene.
Polyester: marketed under the trade names of Dacron and Terylene. Polyester is another man-made
fibre, which follows after Kevlar and nylon in strength. It has a low stretch factor, is easy to handle
and is thus quite suitable for all activities aboard a boat. It comes in both plaited and braided forms,
and is also available pre-stretched. This further reduces its elasticity, helping to maintain a constant
length. Polyester is resistant to acid attack.
Polyethylene: a cheap synthetic fibre, is difficult to knot because of its excessive stretching. It also
loses its shape and becomes very slippery; in addition to these problems it has a tendency to retain
kinks for a long time.
Polypropylene: a soft, malleable and cheap synthetic fibre rope, somewhat weaker than either
polyester or nylon and with a poor resistance to abrasion. It can be knotted and spliced quite easily.
Being buoyant it also makes a good heaving line. Polypropylene is resistant to attack by most acids
and alkalis.
Portuguese bowline see French bowline.
Portuguese sennit (flat): the Portuguese sennits may be made with any number of strands, but only use
two working strands, although these can be doubled, one on each side of the central strand(s) or heart.
This central non-working heart can be any number of strands, although the shape of the sennit
becomes difficult to maintain if you exceed three. Our illustrations show three strands in the heart and
two single working strands.
Start working with the left-hand strand, and pass this under the heart(s) and over the right-hand strand.
A bight must be retained on the left. Now take the right-hand strand across over the heart and down
through the bight on the left. Now you can draw tight both ends, to complete the first knot.
figure 99.1
