Page 9 - Knots in Use (1st Edition)

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Dyneema is the trade name of DSM High Performance Fibers, and
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Spectra is the trade name of Allied Fibers; so far as the yachtsman is
concerned, these two high modulus polyethylene fibres are the same. They
are the material of choice for high performance racing craft, having high
strength (35g per denier, or more than four times that of polyester) and low
stretch (only 3.5 per cent at break), but are expensive. The high cost, though,
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is outweighed on these boats by the benefits of Dyneema and Spectra ,
which include durability and resistance to ultraviolet light. They are always
made up into core and sheath-style lines, and are usually spliced by rigging
experts rather than simple seamen as it’s a tricky process.

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Liquid Crystal Polymer Fibre (LCP), often referred to as Vectran (a trade
mark of Celanese), is a beautiful gold-coloured material that costs about
as much as gold. It’s light, only stretches 3.3 per cent at break, has high
resistance to temperature, but is only moderately abrasion resistant. It is so
affected by 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,
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which is rather less than Dyneema or Spectra , and costs (currently)
around 20 times as much.
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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.

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