furling headsails set flying

[snowleopard]

i have had my jib converted to set flying with a profurl drum (modern version of wykeham martin) and hi-tech luff rope.
unfortunately the top of the sail doesn't furl tightly and in any breeze it unfurls and has to be brought down to prevent it flogging itself to death.

anyone tried this type of sail and found a solution to the problem? i have had various suggestions such as a thicker luff rope, twin ropes etc.

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[tugboat]

Would I be correct in thinking that the Wykeham Martin gear was used with sails that had a wire luff? If so, the wire would, to a certain extent, have resisted twisting and the top of the luff would have closely followed the bottom as it rolled up. Your hitech luff rope, while being strong in tension, probably twists the same as any other rope and is allowing the resistance in the top swivel to hold it back or let it partially unfurl. All IMHO of course.

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[Sunnyseeker]

Just a thought, but have you tried changing the angle of the sheet lead? take it forward and it will keep the top tighter as it furls. On ours with the lead taken aft in stronger wind to twist off the top it wouldn't furl neatly, leaving the top loose, so before furling th elead would be taken forward, its easy if its on a sliding track.

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[qsiv]

Our code 0 and gennaker use the same technology.

Both use twin luff ropes to transmit the torque - the gennaker was really tricky, and had to go back to be rebuilt with PBO luffs before it worked (we need over 4000kg luff tension). One key element is that neither sail is designed to be kept aloft when furled - they are dropped, bagged and stowed. If it were a conventional jib with a straight or hollow luff I'm sure they could stay aloft - but not in stronger breezes.

the problem with the top 1/3 unfurling (or not furling to start with) was cured

a) by more luff tension in the furl, and
b) by twin luff ropes to transmit the torque.

Even so I would rate the gennaker as a marginal, rather than unqualified success - the Code 0 is just brilliant though, and has always been well behaved.



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[Richard_Woods]

We had this problem years ago, but solved it about 1988/89. Instead of using a conventional furling drum we used an endless line. At the time the only available gear was from Sailspar. So we used a modified Sailspar bottom unit and a Harken top swivel.

As the furling line was endless we could just keep pulling until it had all the sail had rolled away. I've used a similar system ever since, althouh I believe most people now make an endless line unit specifically for free flying drifters.

Having said that, I only used the system on what I have always called "drifters", ie masthead free flying genoas. I haven't used it on a "gennaker" ie an asymmetric spinnaker. In this case there will be more material in the head of the sail to roll away and I can believe that that could cause problems.

In practice I've always found it harder to roll the sail away the windier it gets, which is hardly fail safe!

<hr width=100% size=1>Richard Woods of Woods Designs for quality sailing catamaran designs
www.sailingcatamarans.com

 

[Plum]

This ia a normal problem with a Wyckham Martin furlers in strong winds and probably made worse by having a rope luff that may be as strong as steel but not as good as resisting twist.

The solution is to sail down-wind so as to blanket the jib with the main-sail. As the jib drops in the stale air behind the mainsail, roll it quickly. Works every time for me.

Plum

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