What prompted that question was the thought that there might be some tightness at the top of the slot, but when I think it out it doesn't add up, so if the problem is not caused by some interaction between the kicker, mainsheet and halyard, I'm afraid I'm stumped.
loose main sail luff
- Thread starter bogman
- Start date
What prompted that question was the thought that there might be some tightness at the top of the slot, but when I think it out it doesn't add up, so if the problem is not caused by some interaction between the kicker, mainsheet and halyard, I'm afraid I'm stumped.
Javelin
Well-Known Member
Yes it does.
see the various sail maker tuning guides like the one from North Sails
To reiterate - the OP sees his luff tension decrease upwind when main sheet tension is applied.
Mainsheet tension pulls down on the leech and to some extent pushes the boom forward.
If there is any stretch in the main halyard applying mainsheet tension will pull the head of the main downwards.
If there is little or no stretch in the halyard the boom will be pushed forward bending the lower middle of the mast forward.
If there are lowers stopping the mast bend the leech will tension to a point where it will stand up to windward.
Robin
Well-Known Member
+1, Also makesure the halyard can reach full height on initial hoist and is not prevented from doing fully so by a bulky spliced eye to the sail headboard attachment, Maybe also consider using a simple halyard knot instead of a splice to the headboard shackle ,
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Daydream believer
Well-Known Member
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bogman
Member
Thanks for all the suggestions. I did not manage to get out this weekend so will send some feedback as soon as I do.
Just some initial input, There is some space still between the head of the sail and the mast so I am ruling that out at present. I ave a new spinny halyard and I might swap that out for the main halyard just to eliminate that one. I am beginning to think the problem may lie with the kicker which I did not check last time out.
More to follow
Thanks again
Just some initial input, There is some space still between the head of the sail and the mast so I am ruling that out at present. I ave a new spinny halyard and I might swap that out for the main halyard just to eliminate that one. I am beginning to think the problem may lie with the kicker which I did not check last time out.
More to follow
Thanks again
Robin
Well-Known Member
If there is still space above the headboard that might indicate that the sail is not fully hoisted and may be constrained by a splice on the halyard shackle. We had a boat with race sails that was like that and relied on the Cunningham downhaul to fully tension the sail once it was hoisted to the black band at the masthead. This allowed the sail to be set up to be full for llghter winds or off the wind yet with a taut luff for going upwind or use in stronger winds. We were not told this by the previous owner and it took our local sailmaker to point it out to me. there was a simple line from a mast eye passing through the Cunningham eye on the sail and down to a redundant mast mounted winch ( the halyard and all sail controls otherwise went back to coachroof winches. Once we knew this it was an eye opener as we had a better sail than we had thought and the adjustment was very effective. THe boat had been fitted with a North 'race sail' for an AZAB race and probably the PO Didn't even know what he had as he was no racer. When we had a new mainsail made later we retained the Cunningham too but were not quite as extreme on the full hoist luff length, We also switched to an all Dyneema halyard and used a simple halyard knot to the headboard shackle.
