All good points Arne - it brings us back to the near-philosophical debate of just what exactly is efficiency.  And while you are doing your cost-benefit analysis, you'd do well to do a bit of personal analysis to go with it.  Be honest now: if your destination is dead to windward, do you always sail, or will you choose to motor sail - or even to motor?  I am continually astonished at the number of people with complex, expensive, hard-to-handle rigs, set up for optimising windward performance, who choose to motor when they can't lay the course. 

It's one thing to like the idea of having a rig that will get you to windward faster than any other, it's another to spend all that time and money on it, and then use the iron yuloh rather than beat.

Of course, we must not ignore the tweakers and fiddlers: they just want to try out something new.  It's what they enjoy doing and that in itself justifies the time and money spent.  And the rest of us often benefit from their efforts.

I agree with David.  Camber is all important.  If you dont have enough drive you will never get to windward.  Both the cambered rig and the wing rig will accomplish this

The next important thing is to reduce drag.  The rounded leading edge helps a lot with this and also increases lift.  Both the split rig and the wing will do this.

The wing further reduces drag by getting the mast out of the flow.  It does this at the expense of reducing camber and increasing complication and weight.  No one has yet proved that the trade off is worth it but David has come very close. 

David's next rig will be very interesting to see.

My very first wingsail, back in 1977, had no camber. I was looking for an advantage from having a round leading edge and no parasitic drag from the mast. If there was any, it was very slight. I soon changed the battens to make them articulate.

When I saw Mudskipper, I'm pretty sure there were battens that added camber in a very complicated and adjustable way.

My belief now is that the most important upgrade from a flat junk sail is to add camber. Doesn't matter whether it's with shaped panels, or hinges, or both. Only after that do you start to think about a doubled sail to add the round leading edge and to hide the mast. That will probably improve the performance, but not by a huge amount.

Robert Biegler wrote:

I have no personal experience, but spoke with the owners of Mudskipper (subject of an article in the newsletter a while ago) when they came through Trondheim.  Mudskipper has a symmetrical wing junk rig for exactly the reasons you outline.  I was told one surprise was how well the rig works in very light winds with a swell.  Seems the round leading edge is much less vulnerable to a stall caused by rolling.

Interestingly, after sailing aboard Arion on Lake Macquarie last year, and observing how well the boat sailed with its very simple, uncluttered flat sail, Peter and his partner, Ruth, contemplated changing their rig to a similar design.  This has something, in part, to do with the fact that Mudskipper's rig has sailed a great many miles and is due for a refit. 

Hello,

I'd been sailing around WhitSundays Islands last week and had some thoughts about sail designs. (side note: met up with Graham in s/v Arion) I would like to build a wingsail, but a simple one with a symmetrical airfoil. I came up with an original cambered wingsail design, but now feel the extra mechanics of reversing camber will be too complicated to warrant the increased lift. 

Basically, the wingsail would be a Gallant rig without the rotating mast. The battens will be shifted slightly abaft to create positive stagger to handle the single sheeting.

I read somewhere in this forum, that a previous Gallant rig cruiser was converted to junk rig, and the speed went up 1-2 knts! How is this so?

I thought a curved 'thick' airfoil would mostly perform better than a flat 'thin' airfoil. I wonder how a cambered 'thin' airfoil will rate against the 'thick' airfoil.

Any thoughts from wing builders out there?