Page 11 - Colin Jarman "The Essential Knot Book"

ultraviolet light that it is stored away from all daylight prior to being

incorporated into a rope’s core. It’s three times as strong as polyester, which is
® ®
rather less than Dyneema or Spectra , and costs (currently) around 20 times as
much.

®
PBO (polyphenylene-2, 6-bezobisoxazole), or Zylon (a trade mark of Toyobo
Co), is the top of the range of the exotics. It is over five times as strong as
polyester with 3.5 per cent extension at break, but it hates ultraviolet light and
chemicals, although it doesn’t mind heat. It costs a staggering 35 times as much
as polyester at present, thus putting it into the realms of fantasy for most
ordinary sailors.

KNOTS KNOCK STRENGTH

This is a fact far less widely recognized than it should be. Any knot will
seriously reduce the strength of the line it is formed in, and to demonstrate this
English Braids carried out a short series of tests exclusively for this book.

It was found that a Bowline reduced the strength of a line by 30 per cent, a
Figure of Eight loop by 28 per cent, and a Reef Knot by 50 per cent. Considering
the number of occasions in which we use these knots on board our boats, these

are pretty serious numbers, and should be borne in mind when selecting both
ropes and knots for particular jobs.