Dyneema or kevlar for forestay?

   Just snapped the old Kevlar forestay on my old (1999) 14 at the weekend, fortunately it was downwind back to the slip so the kite kept the mast up.
The old forestay is Kevlar (in an outer) 2:1 wire going to a 6:1 rope, what is generally used now? Dyneema/spectra core? how thick?

Author	Message Share Topic Printable Version Delicious Digg Facebook Furl Google MySpace Newsvine reddit StumbleUpon Translate Twitter Windows Live Yahoo Bookmarks Topic Search Topic Options Post Reply Create New Topic
H4marine Send Private Message Find Member's Posts Visit Member's Homepage Groupie Joined: 16 Jan 08 Location: United Kingdom Online Status: Offline Posts: 46	Post Options Post Reply Quote H4marine Report Post Quote Reply Topic: Dyneema or kevlar for forestay? Posted: 19 Aug 13 at 11:10am
	Just snapped the old Kevlar forestay on my old (1999) 14 at the weekend, fortunately it was downwind back to the slip so the kite kept the mast up. The old forestay is Kevlar (in an outer) 2:1 wire going to a 6:1 rope, what is generally used now? Dyneema/spectra core? how thick?
	sailonline.org sailport.se

Jack Sparrow Send Private Message Find Member's Posts Visit Member's Homepage Really should get out more Joined: 08 Feb 05 Location: United Kingdom Online Status: Offline Posts: 2965	Post Options Post Reply Quote Jack Sparrow Report Post Quote Reply Posted: 19 Aug 13 at 11:35am
	MRig - Marlow Ropes... although I can't see it when I just searched? It is a DM20 fiber... DM20 Dyneema LINK
	Farr 3.7 Class Website Farr 3.7 Building - Facebook Group

H4marine Send Private Message Find Member's Posts Visit Member's Homepage Groupie Joined: 16 Jan 08 Location: United Kingdom Online Status: Offline Posts: 46	Post Options Post Reply Quote H4marine Report Post Quote Reply Posted: 19 Aug 13 at 11:56am
	Thanks Mr Sparrow
	sailonline.org sailport.se

carshalton fc Send Private Message Find Member's Posts Visit Member's Homepage Really should get out more Joined: 26 Jan 05 Location: England Online Status: Offline Posts: 2337	Post Options Post Reply Quote carshalton fc Report Post Quote Reply Posted: 19 Aug 13 at 12:02pm
	Most 14's have wire or Vectran (Marlow Excel V12). The forestay on my Morrison 12 is 3mm wire, long lasting and easy to use. P&B custom made a new forestay and shrouds one for us a week ago out of the hamma pro wire 7x1.
	International 14 1503

H4marine Send Private Message Find Member's Posts Visit Member's Homepage Groupie Joined: 16 Jan 08 Location: United Kingdom Online Status: Offline Posts: 46	Post Options Post Reply Quote H4marine Report Post Quote Reply Posted: 19 Aug 13 at 12:33pm
	Mine has wire up to a pulley on the mast giving 2:1 then Kevlar (or had) down to the bow. Line will be easier for me to make up, just want to make sure it's strong enough. Thanks.
	sailonline.org sailport.se

JimC Send Private Message Find Member's Posts Visit Member's Homepage Really should get out more Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6662	Post Options Post Reply Quote JimC Report Post Quote Reply Posted: 19 Aug 13 at 1:57pm
	I'd avoid Kevlar. Snaps with little warning.

gbr940 Send Private Message Find Member's Posts Visit Member's Homepage Posting king Joined: 04 Jan 06 Location: United Kingdom Online Status: Offline Posts: 198	Post Options Post Reply Quote gbr940 Report Post Quote Reply Posted: 19 Aug 13 at 4:32pm
	definitely vectran
	RS400 GBR1321

Daniel Holman Send Private Message Find Member's Posts Really should get out more Joined: 17 Nov 08 Online Status: Offline Posts: 997	Post Options Post Reply Quote Daniel Holman Report Post Quote Reply Posted: 19 Aug 13 at 5:15pm
	I'm going top be controversial! I use marlow sk78 max dyneema on the forestay and capshrouds of my 14. Quarter of the weight of dyform, and similar price once swaging has been taken into account. DM20 dyneema (M RIG is an english braids product based on this fibre I think) was created for the offshore mooring industry, and has very little creep, but like vectran has lower moduluis of elasticity than dyform or sk78 max (i.e a 3mm rope of a given length will stretch more under a given load) I use 4mm Sk78 max on the forestay - 3mm would have better modulus and breaking load than 3mm dyform, but I have a 1mm margin for wear and tear. I use 2.5mm on the caps. Make sure you do good splices, tapered and with plenty of bury. The one thing I would say is that all woven dyneema products will have an initial mechanical creep associated with the construction and splices. Don't be suprised to take 100mm out of a 6m stay over the first couple of sails. once this is done it will be rock solid. The amount of time that a racing dinghy is tensioned up is negligible in the context of visco-elastic creep. If you take the mast down and put it up again, the stay will recover some of that mechanical creep again, so will appear shorter on rerigging, but that beds back in quickly.

H4marine Send Private Message Find Member's Posts Visit Member's Homepage Groupie Joined: 16 Jan 08 Location: United Kingdom Online Status: Offline Posts: 46	Post Options Post Reply Quote H4marine Report Post Quote Reply Posted: 19 Aug 13 at 6:32pm
	Brilliant, thanks Daniel I feel quite well informed now.
	sailonline.org sailport.se

laser193713 Send Private Message Find Member's Posts Really should get out more Joined: 13 May 09 Location: United Kingdom Online Status: Offline Posts: 889	Post Options Post Reply Quote laser193713 Report Post Quote Reply Posted: 20 Aug 13 at 9:04am
	If it is running through a turning block and will be static for long periods Vectran can let go without warning. Modern Dyneema products are just as good and will give a bit more warning before they let go. I am amazed you snapped it while going downwind, if the mast stayed upright then how was the forestay under any tension at all!?