too much sail twist...please advise..!

Hello sailors out there, I have an old “Marblehead” boat in rather good shape but with crude sails - single panels and no battens…:trouble:.!&p=64697#post64697
So I first added battens to both sails by glueing thin strips of 0.4mm ply with thin epoxi. Worked out fine but of course the battens did not help the excess twisting of the mainsail with the upper portion falling off to leeward in a gust. I do not like that so what should my next step be…??..maybe a single panel sail is not good enough…?..please advise…!..Thank you…!

Too much twist can be caused by the mast tip bending aft - preventing sufficient leach tension. If you do not have any prebend in the mast, then you could add some. That would allow you to achieve proper backstay/forestay tension without the mast bending aft.



I think messing about with mast bend will go some way to improving the sail shape but, and it’s a big but, the main problem (as you’re already aware) is that it’s a single panel sail. These are fine for scale models but as the marblehead has such a high aspect rig the shape is never really going to generate the power of a well made 800 sq inch sail plan. If you read through the following you’ll pick up some pointers for making your own paneled sails -
If you follow the various links from this page it should give you sufficient knowledge to build a ‘Claudio gadget’ and then experiment with some sail making. Good luck!



PS: Before posting this I had a look at your other posts - you really do have a most beautiful playground for RC yachting.

The problem is the result of the old woven mainsail finally having lost its integrity. What ever kind of binder was used has deteriorated, and the weave of the cloth itself no longer has the strength to resist the stress put into the sail by the wind. There is virtually no rigging adjustment that will cure the problem as the leech is now longer than the body of the sail immediately ahead of it. The cure would be new sails.

Single panel sails can be constructed for M-class high aspect ratio rigs that shape very well and have long service lives. Look at some of the rigs at this year’s USVMYG championship, tall sails with plenty of controllable camber. Not too many sail makers remember how to make such sails that were the standard back in the 1970’s and early 1980’s.
Rod Carr, CARR SAILS since 1969

Hi Harald,
Are the sails original to your mast/rigging?
It almost looks like they’re too big, so you can’t make fine adjustments between the head, tack and clew.
I can’t tell from the pics, but perhaps you can reduce the length of your boomvang, bringing the end of the boom downwards, thus adding some tension to the leech.