johnalison
Well-Known Member
So long as it is not tighter than the forestay tension.
Stretchy main halyard
- Thread starter jaminb
- Start date
geem
Well-Known Member
It's so strong it doesn't matter. We have been using a bowline for 36,000nm in our Dyneema 10mm halyard. Twice over its life we have shortened the line by 300mm. This is more about where the line goes over the mast sheave than an issue with a bowline. I never see the point of a spliced end or shackle in the main halyard. The bowline can be tied in sightly different location each time such that you move the chafe point slightly
Chiara’s slave
Well-Known Member
A 10mm dyneema halyard is comfortably strong enough to pick your boat up with, so yeah, you don’t need that strength for a halyard. Dyneema for halyards is all about the stretch. Even with only 20% of it’s strength left, it’s still enough to rip the headboard out of your main.
GHA
Well-Known Member
Actually much more complicated than that..... a bowline in slippery D12 will just slip through before it gets anywhere near MBL. Just tried it, few hundred Kg it slips through quite gently with an occasional few millimeters "bump" .
Chiara’s slave
Well-Known Member
Not much excuse for not splicing D12. It only takes a bit longer than a bowline.
GHA
Well-Known Member
Agree, quick, tidy, crazy strong, can be made adjustable.
Knots will just slip out of uncovered dyneema.
geem
Well-Known Member
Wrong stuff. We are talking cruising boat halyard. Use Marlow D2. Comes with a cover. It's still Marlow racing spec rope
geem
Well-Known Member
D12 is horrible to handle. We hoist our main by hand until the last 2 metres. D2 is far better for this.
We have two sets of runners. One on the main mast and one on the mizzen mast. Both are D12. It's not nice handling that rope and we don't since they have normal rope on the pulley blocks. The D12 does chafe as well. I tie small string on to the mizzen runners to control them. They have gone wooly in the area where the string ties.
GHA
Well-Known Member
Post was a response to some wrong info, not what to use!
Edit - though on the to do list is to splice just under a masts length of D12max into the main halyard so it will be nearly all dyneema doing the work when sail is raised.
Might be an option for the OP.
Similar happening with the reef lines, 5mm dyneema is so light & low friction it runs through so much easier, big improvement.
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jaminb
Well-Known Member
Chiara’s slave
Well-Known Member
We only used D12 for standing rigging, like the bobstay, and side stays for the bowsprit. Our dyneema halyards are covered. We use it on the XOD for moving stuff, but generally on the non handled parts of a cascade. Immensely useful in the right applications, but it’s not the right rope for a cruising halyard, as you say. Even if you wear gloves, covered dyneema every time for a rope that is handled.
Chiara’s slave
Well-Known Member
Thats the covered stuff. If it’s what the seller says it is, it’s perfect.
GHA
Well-Known Member
Be nice if the seller said what dyneema it is, maybe try a search for sk75 dyneema core?
geem
Well-Known Member
Just be careful with ebay purchases of 'dyneema' I tried that once and got the stretchiest halyard on the planet. I only buy dyneema from reputable suppliers these days
Chiara’s slave
Well-Known Member
Maybe try Jimmy Green and Aladdin’s cave. They might have an offcut for a decent price, and they’ll tell you what it is without you asking.
jaminb
Well-Known Member
Sorry thinwater missed your post. My ladder slides up the mast track so dont think pretension is necessary?
thinwater
Well-Known Member
Yes, considerable pretension. Certainly more than body weight. That is how you keep it from stretching with every step. If pretensioned, it cannot stretch due to body weight, because that stretch is already present.
Yup, lots of people trying to spend you money on Dyneema. For a cruising boat with polyester sails it is nice, but totally not needed, and polyester will last longer and handle better. I've have Kevlar, wire, polyester, and Dyneema. By all means change, but plyester is NOT the reason for the excessive stretch you are seeing.
Most likely the jammer is slipping.
- Rebuild. The cam teeth wear, and if it is original, they are not grabbing.
- Treat the rope. Moving the bite point is good. You might also try soaking some Maxijacket into the rope along the bit zone (~ 2 feet) to firm the rope.
- Wrong size. Is it possible the rope size has been changed and is now too small for the jammer? It will slip for sure.
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geem
Well-Known Member
This is not my experience. I have had several polyester halyards with over 300mm of stretch on a 17.8 mast. The effect on sail trim is terrible. These are not new ropes needing their initial stretch. They are well used but now retired as I couldn't tolerate their terrible stretch. They were not used on jammers but had their own dedicated ST winch. No slipping. Just very stretchy rope. Dyneema is a game changer for me as a keen cruiser
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fredrussell
Well-Known Member
Just a warning: I bought some Kingfisher 10mm ‘cruising’ dyneema a year or so ago and the braid outer is not looking too clever near clutch. It’s a hideous outlay but if you can, get Marlow or English Braids or some other decent stuff. I’ve bought Kingfisher braid on braid before and it’s been fine, but my halyard will need shortening soon which is a nuisance as I’ve put whippings on where all the reef points are.
Chiara’s slave
Well-Known Member
Agree completely. Theres always a bit of stretch in polyester rope. It may not be much, but it will always manifest itself at a bad time. Just a few inches is enough to mess up your sail shape in a strong breeze, just when you’re trying to go to windward.