Barry & Meps / Stellrecht & Schulte wrote:

Paul Thompson wrote:However, when you go to shaped panels, the the standard rules are only a guide as because the panel has no diagonal stiffness, the panels is not contained by the cloth to the same extent.

However it would still be wise to check before hand using the PJR method to make sure that the stagger produced by your sail shape will be negative. Then you are unlikely to have problems.

Exactly the problem I'm thinking about.  I did start with boom angles based on the PJR 1% stagger calculation, but when I realized that the cambered panels wouldn't have appreciable diagonal stiffness, I felt a bit lost on how it would end up working out.

In my case, my mizzen PJR would tell me to make my mizzen at 11 degrees.  I've drawn both booms at 10 degrees, so PJR would give me a bit less negative stagger (near zero, but I've not calculated exactly).  I was thinking that PJR would put my main at 9 degrees.  Now I'm thinking about it again, and I realize that the calculation didn't consider that my main is a split sail, so I'm doing the calculation based on the wrong batten length.  Better go back and re-check that calc, especially since I haven't cut the main out yet.

Thanks for the report!

Barry

Barry, I should have said positive batten stagger But my fingers and I were apparently thinking of different things :-(. I have corrected my original post to reflect this.

I think however that you also meant positive stagger when you replied. If not, sorry to have mislead you.

Positive stagger is when the battens stager aft when furled or reefed. If you have single sheeting, this is what you want. If you have double sheeting it does not matter so much.

One of the key reasons for checking stagger (apart from sheeting) is to make sure that the yard remains on the mast.  This is something you need to be sure of with your mizzen as you have very little balance on that sail.

The key thing to take home is that while you should check and design for a positive (battens stagger aft) stagger, when you put camber in those rules do not hold so well. The more camber you have, the looser the fit of the rule becomes.

But generally the parallelogram type sails like HM and van Loan tend to have positive stager. Fanned sails are another story.

Barry & Meps / Stellrecht & Schulte wrote: Does anybody know how this rig reefs?  I'm wondering if there is a batten stagger problem where the boom sticks out aft of the rest of the sail bundle as you reef?

I see that Aphrodite has double sheets, so this sort of stagger isn't going to foul much of anything, but I would prefer to do otherwise, so it will matter to me.

Thanks!

Barry

Aphrodite has normal (ie. positive) batten stagger just like the HM rigs have. You can checkout what your batten stagger will be on the drawing board before hand. PJR tells you how.

However, when you go to shaped panels, the the standard rules are only a guide as because the panel has no diagonal stiffness, the panels is not contained by the cloth to the same extent.

However it would still be wise to check before hand using the PJR method to make sure that the stagger produced by your sail shape will be positive. Then you are unlikely to have problems.

Does anybody know how this rig reefs?  I'm wondering if there is a batten stagger problem where the boom sticks out aft of the rest of the sail bundle as you reef?

I see that Aphrodite has double sheets, so this sort of stagger isn't going to foul much of anything, but I would prefer to do otherwise, so it will matter to me.

Thanks!

Barry

Kurt Jon Ulmer wrote:

.

.

.

My gut feeling after a couple of good sails on Aphrodite is that the Van Loan pattern Paul chose, with roughly parallel battens, is a very good choice for that approach to camber. High-peaked yards might extend the effective luff, but any camber in peaked-up panels could be ruffling the air more than deriving forward lift from it. 

.

.

Cheers,

Kurt

Stavanger, Mon

                  The performance of the fanned top section.

Kurt.

It is easy to think that a fanned top section of a cambered panel junk sail may produce more drag than lift with the wind having to climb over the battens. However, practical experience with sailing my Johanna with only 3 panels set has proven that the fanned top indeed is efficient both when it comes to driving force and pointing. I guess she points roughly 5 -7° worse than with full sail, but then one must remember that the windage of boat and mast has risen compared to the reduced sail area.

Arne

Aphrodite's rig deserves a full write-up, which I hope Paul will do. I was involved as an extra hand to help finalise the setup Paul and Annie had started.