Annie Hill wrote: I'm not sure that you've quite followed Richard's idea.  What I believe he is suggesting is that subtle adjustment of the length of the lacings would effectively produce camber.

Just so. Although it might also produce scalloping, flapping, and drag!

I suspect he doesn't intend to use stainless steel battens, but would use alloy.

Aluminium alloy tubes. They need to be smooth and circular to allow the loops to slip round when tacking. However, they might also suffer from chafe over time from those same loops, comparable with the effect parrels have on masts.

Frankly, I can't imagine anyone trying to change panels between battens while offshore.  It would be an horrendous job with the boat bouncing around, the sail swinging and one trying to tie a bit of string, not tight, but to a certain length.  I don't think the little toggle grips would prove to be strong enough from having used them over the years.  But it's an interesting concept.

I'm not really imagining changing panels under normal circumstances when offshore, but only if a batten breaks or a panel is torn. The idea about changing panels was really about trying out a slotted rig, doing other experiments, or perhaps changing from a passage to coastal rig.  That would most likely happen in harbour.  Likewise adjusting camber, although I think it would be more feasible.

Those toggles are surprisingly strong, and the load would be spread quite a long way. The real question is whether small constant movement makes them give up, so that the panels would become baggier and baggier. Or whether the springs rust in sea air. I'll have to devise a test.

Paul Thompson wrote:

Richard, sorry to disillusion you but the Thais have used that system on their junks since time immoral,

I say, Oracle, that's a bit thick.  I don't believe the Thais have ever been significantly worse than the rest of us.

although on much bigger junks than yours. There was even an artical about it in one of the early News Letters (> 40) but I no longer remember the exact one. I tried out a more hi-tec system of the same type when I rigged Carl Bostek's Aphrodite. It worked fine but in the end I did not really see any point in it. 

I'm not sure that you've quite followed Richard's idea.  What I believe he is suggesting is that subtle adjustment of the length of the lacings would effectively produce camber.  I suspect he doesn't intend to use stainless steel battens, but would use alloy.  Frankly, I can't imagine anyone trying to change panels between battens while offshore.  It would be an horrendous job with the boat bouncing around, the sail swinging and one trying to tie a bit of string, not tight, but to a certain length.  I don't think the little toggle grips would prove to be strong enough from having used them over the years.  But it's an interesting concept.

Richard, sorry to disillusion you but the Thais have used that system on their junks since time immoral, although on much bigger junks than yours. There was even an artical about it in one of the early News Letters (> 40) but I no longer remember the exact one. I tried out a more hi-tec system of the same type when I rigged Carl Bostek's Aphrodite. It worked fine but in the end I did not really see any point in it.