Ropes used for different types of projects

Rope makers bother to savours confusing us with science and/or extraordinary polysyllabic names. I'll try to cut through the guff just a bit of.

Dyneema
Identified as Spectra - this usually is a high modulus polyethylene fibre. T
Polyester
Referred to as Terylene or Dacron, polyester is the stuff which retreat most rope and line is made of. It is resistant to rot and ultra-violet (UV), sinks in water and comes in a assortment of constructions:

3-strand pre-stretched - often are spliced in the normal fashion, however it is a good idea to use 4 or 5 tucks instead of the 3 used in natural fibre ropes. This refers to an extra tweak imparted during the making of the rope making more suitable for halyards and bell ropes. Very important, that - could you imagine the cacophony that result from using stretchy rope? The snag with this construction is that it can kink, so it’s unusual employ it as a sheet.

Plaited pre-stretched - will make all sizes from 1mm upwards but is not usually used much above 8mm where braided rope (see below) takes over. This is well behaved, and finds use as lacing, messengers etc. in the smaller sizes, and halyards in the larger. But it can be readily spliced - maybe you knot or seize it.

Braided rope - right here is the stuff most widely used for sheets. Available in a variety of constructions and outer finishes, it starts at about 5mm. The kind we list is matt finish braid outer on braid core. It is spliceable - with some practice - but each manufacturer uses a slightly different construction, so you need to follow the instructions appropriate to that rope.

Polypropylene
A tad bit more stretchy than polyester, polypropylene floats in water, and will over time degrade under UV. It tends coming in 3-strand form - except ski/rescue ropes which are braided - and the main variation is the way in when the material is incorporated into the rope. I don't pretend realize the minutiae of the process, but could give some feel for the results:

Staple spun polyprop - the hairy cheap stuff you might get in blue, orange or white, and and that is seen on farms, fishing boats and building sites. Apart from moorings, not often seen on yachts.

Mono/Multifilament polyprop - deceptively like polyester, but it does - as pointed out - degrade over time and can melt if surged round a mooring post. How to tell one from the other? Chuck it into the water - holding onto one end! If it floats its polyprop. It is not a bad rope, but be aware of its limitations, and keep looking for the brittleness which develops with age - a bit like splinters that appear on the outer fibres.

Hemp-style ropes - these are now less costly than the natural ropes they replace and are better behaved and longer lasting. They come in a soft finish, which looks well when new, but is amazingly stretchy, not particularly long-lived, but more comfortable for sheets. The harder finished varieties - just for instance "Leoflex" or Spunflex - look a bit shiny when new, but last longer - typically 10-15 years, stretch much less, and are cheaper. Visitors here can see it used on our flagpole(!) - currently 6 years old and showing no sign of degradation.
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