Originally Posted by ack
(Joe Cooper). He's a big proponent of dyneema
solent stays on cruising boats. He suggests rigging a fairly simple block and tackle on the deck to tension the stay.
Joe's a good guy.
His description of the tackle system does steps around the two most difficult parts
of the set-up: #1 You need a pretty significantly strong jammer to hold the tackle line. It depends on the boat size, but the Spinlock ZS jammer is the hardware
of choice. #2 You need to be able to create a fair lead for the tackle line from the innerstay back to a winch - that's easy on some deck layouts but harder on many others.
For the tackle rope
. . . you wil want to use uncovered dyneema (as he shows in his pics) for the area that is in the tackle (to reduce friction and chafe) BUT you will need it covered where it is held in the clutch
(to avoid slipping).
Just as a small detail on dyneema innerstays - to make the end splices properly you need a quite long bury. That bury length will be double the diameter of the rest of the line and you need to factor that into your hank sizing, so the hanks don't jam on the extra diameter. Its not a big problem, but something to be aware of.
Originally Posted by smurphny
Great point Malbert73. Would like to hear from someone who has calculated the forces involved in using a halyard winch to tension a temporary stay.
Hard to calculate because the peak loads will be shock loading due to mast whip - which will depend on the mast section. But I would venture to guess that this will NOT be a significant extra loading on any properly built mast step.
The things that will break in order are #1 any halyard clutch - clutches are not typically designed to hold stay tension, #2 the halyard sheave - sheave might deform or it might be pulled out of the mast, #3 the winch pawls.
If you used a 2:1 halyard you would both reduce the compression load and increase the possible stay tension.
Another operational thing to think about with the method is that the stay is NOT tensioned when you are trying to hank on the sail and hoist it. So the whole thing is going to be flopping/flogging around.
Also again related to the splice bury - in this method the bury will probably be going thru the sheave at the bottom of the stay (depending on how close to the deck you want the tack) so the sheave needs to be sized for double the dyneema line diameter.
Do note that you need a specially built or modified staysail for this to work - with a high modulus rope
built into the luff. You CAN NOT use this technique with an unmodified normally built staysail - the luff will just be stretched and pulled apart.