Polyester, capitalism, and wooden boats.

[George.]

We all profess to hate plastic. Yet most of us use polyester ropes and sailcloth.

In Brazil, you can get two basic kinds of polyester rope. "Ordinary" cheap crap, and "pre-stretched" fancy sailor's stuff.

Dalia has well over 800 meters of sheets, halyards, outhauls, tack lines, preventers, etc., etc. Maybe as much as 1000 meters, if I count reefing lines, downhauls, and lacings. Guess which kind we bought on our limited budget? ;) :eek:

Now, here is my question: can you turn what we jokingly call "post-stretched" polyester rope into pre-stretched by, say, tying it to a mooring and motoring hard against it, or some similar trick? I mean this in all earnesty - I have noticed that after a while, the ordinary polyester becomes "pre-stretched", in the sense that it stretches a lot less. This is particularly evident in halyards, which when new are barely set "hard" before they sag and slack us into leeway-making towards a lee-shore, and when used hard for a couple of months behave a lot better - no need to re-set after the first ten minutes in Force 5.

Is there a short cut to stretching polyester into seamanlike discipline?

PS: please, no lectures about "buy the good stuff to begin with" unless they come with a check attached... ;)

[Don Kurylko]

30 years ago, I used to tow brand new “cheap” Manila rope through the water to get the stiffness out of it. I simply tied one end to the transom and let the rest out in a long line. That may help. Don’t forget to rinse the salt out afterwards.

[uncas]

and if you're under power...don't put the engine in reverse... :D

[Dan McCosh]

You can hardly find anything cheaper than Sta-set around here, so the issue doesn't seem to come up. I think the stuff is low-stretch due to the weaving process, rather than being pre-streched, but don't know. The idea that you could stress a line an it wouldn't stretch in the future makes some sense, but in the case of nylon, a sever stress that hardens the rope also weakens it. Don't know about polyester.

[Lucky Luke]

Yes you can, George.

In the years I was racing, which is about 40 years ago, although using pre-stretched polyester (no financial problems on racing yachts) we would "super-pre-stretch" some ropes by winching then in, real tight, and taking in the slack again and again for about an hour. We would do that with boat alongside the quay, and the other end of the rope fastened to whatever was at the right distance....and strong enough to stand the pull. The reduction in diameter during that pull was spectacular: perhaps 1/4th I'd reckon, but the stretching ("lengthening") only one meter on a hundred meter rope. Mind it: all the ropes I was using were doubl braided polyester, continuous fibers, already very "pre-stretched". They were discarded after one season anyway :cool: .

The drawback is that these ropes became extremely stiff then. After doing that for sometimes (for the spinnaker guys and mainsail down haul), I finally decided, for my spinnaker guys and for a part of the mainsail preventer ( the single line section, to which was fitted the purchase) , to extract the core of braided ropes (8 strand inside, 16 strand outside), and replace it with a steel wire, the outside plait becoming just a protection, and much better for the hands (and the winch drums) than would have been bare steel. When kevlar came up, all this became obsolete :D .

Main hallyard were all steel, and genoa hallyard steel with rope (rope spliced to steel) for the lower section: for the cleat. Spinnaker hallyard better have some elasticity.

In your case, hallyards and reef lines (exepted fisherman and balooner hallyards...if someday you have these ;) ) would benefit from that. I would just recommend you to do it by stages, in order not to go too far and have your lines become too stiff. On absolutely non-pre-stretched ropes, I would not be surprised of a lengthening nearing 5%. In some instances (part of your standing rigging), steel inside plait can be real good to prevent chafing, better than ugly "baggy crap-crap" whatever they call it, or other plastic hoses !

Edited to add: I hope that you are talking about polyester (alias terylene, dacron), and not this real crap that is polypropylene... :rolleyes: )

[ 12-12-2005, 10:21 PM: Message edited by: Lucky Luke ]

[Hwyl]

I'd been meaning to answer this. I cannot say anything that Luc has not said already.