Sail matterials
Printed From: Yachts and Yachting Online
Category: Dinghy classes
Forum Name: Dinghy development
Forum Discription: The latest moves in the dinghy market
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=1203
Printed Date: 15 Aug 25 at 9:13am
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com
Topic: Sail matterials
Posted By: Peter Rhodes
Subject: Sail matterials
Date Posted: 17 Nov 05 at 8:13pm
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For my As level physics coursework I am doing a presentation about "designer materials" mine is about sails and my current reserch suggests that carbon fibre is totally supirior to kevlar by Youngs Modulus, Ulimate tensile strength and density, so why have I never seen any cf sails even on money no object ocean racers? or have I got the wrong information?
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Replies:
Posted By: JimC
Date Posted: 17 Nov 05 at 10:32pm
Here y'are. You won't see sails woven from carbon, but carbon sandwiched in a mylar weave like these isn't that unusual in the more advanced classes. 
By the way, these sails are Fyfe NZ, built in 2002. These are early tuning photos, not optimum setup ones. |
Posted By: Marine Boy
Date Posted: 17 Nov 05 at 10:43pm
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North Sails have been using CF since at least 2003 and I would think that most other big lofts have also been using it.
http://www.northsails.co.uk/sails/mumm30/m303dl.html - http://www.northsails.co.uk/sails/mumm30/m303dl.html
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Posted By: Timmy
Date Posted: 17 Nov 05 at 11:31pm
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Hi you seam to have some wrong numbers SP have a good basic guide http://www.spsystems.com/ - www.spsystems.com then look under solution, general information then have a look at guide to composites. Some of the data is a bit out of date. Also be careful sometime people call Kevlar Aramids, where Kevlar is a specific fibre from the Aramid group.
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Posted By: Bumble
Date Posted: 18 Nov 05 at 9:21am
I think this info is actually for composites which is a ratio of strength in compression to strength under tension adjusted by a factor of the composite separation.... while saturated with sp's gunk
His ultimate tesile figures, right or wrong, do show correctly that carbon fibre has a greater tensile strength than others. In sails however this isn't the MAIN (geddit) factor. Carbon is like steel, in that, once its distorted under stress beyond its range of elasticity (which is minute) its strength drops off, alot. In sailing terms, put it in a flapping sail, and the threads can break. The solution, as north and many others will tell you is to make the threads as small as poss and then combine them...... like in steel wire...... giving better range for the same strength.
The reasons kevlar is so good is you can flex it, bend it press it....... its ability to withstand repeated flexing means you can glue a workable amount into the sail and it can flap and fold etc.
The strength to weight of a sail has never been about the re-enforcements, its about the glue that holds them in and how elastic that is. At present a glue light enough to take full advantage of Carbon fibres S/Weight hasn't been invented so a kevlar sail can be made as light..... and for less cost. The only reason CF sells well is cos it sounds really hi tech - but time will tell - I would expect it to be the material for the future. |
Posted By: big man is back
Date Posted: 18 Nov 05 at 11:19am
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you could do with getting on to bainbridge. they are very good. my mum makes spinnikers and is expanding in to jibs and thats the cloth supplier that she uses.they might evern send you out a catalog and give you some samples to look at. they sent my mum loads they are very helpfull ------------- maybe theres more to life than being really really really really..........really good looking |
Posted By: Boatboy
Date Posted: 05 Dec 05 at 1:07pm
you need to do some serious research as your figues are way out for aramid( kevlar is duPont's tradename for aramid also try twaron which is another trade name for aramid) the figures i have are UTS=1600 MPa E(youngs modulus)=50 GPa figures for aramid are dupont's kevlar 49 also if you look at the density you have for carbon you need to add a zero so i reads 1600 kg/m3 also many sailmakers use carbon in their sails have a look through a few websites eg norths, sobstad, quantum, uk sail
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