I’m starting this post as there seems to have been some interest in the way I rigged Proud Mary, and also because I need some advise.

Proud Mary’s rig is a Gibbon sail and a Gibbon/Dierking mast arrangement.

The Gibbon sail was improved by Garry Dierking, I believe, influenced by the windsurf sail design. By all accounts the Dierking sail is much more efficient sail.
My choice of a less efficient sail comes form it’s simplicity and possible easy reefing.

The sheeting point, as in any boomless sail varies with the point of sail, so I have the main sheets coming from the bows, thru a double block at the clew of the sail and then to the cockpit. in this arrangement the sail “chooses” the sheeting angle.

The mast is back stayed to the ama, and stayed to the bows. I have adjustments on the stays to control the tilt of the mast. This is the main difference from this rig to the original Gibbon’s one that had a fixed mast, putting the sail too far back, and it was one of the modifications Dierking made.

The mast base goes thru a slot, just over the with of the mast but long enough to allow it to move from side to side. The original idea was for the base of the mast to have a slot that would go into a horizontal axle, but as I had a salvaged windsurf mast base I used that instead. With this arrangement I was aiming at not having to use mast stays, at least not the annoying ones that go to the bows (the one not in use always drags in the water or gets in the way somehow, and windage might be something to consider).  The tilt angle of the mast would then be controlled by restricting the course in the slot.
This arrangement also keeps the mast from falling back in the case of going aback or wile setting it up, and allows it to be placed in the lee side of the main hull, freeing the platform and making “butt steering” easier.  After a trial without the sail I chicken out and kept the stays, but if this arrangement is made with a stronger mast (mine is a 2’’ aluminum/ aluminum from a lazer). I might still try it in a very calm day…

As sail, I first used a 9m kite, passed the yard thru the leading edge pocket (without the bladder), and had the sheets connected to the end of the middle inflatable batten.  I tried to use it with the battens inflated to keep the sail more rigid, but never worked that well, and the usable area of the kite was reduced to a triangle. The shape was was too round, and it “ballooned” too much.
The sail I"m using now is also made of a kite, but it was cut as a triangle. I sewed pockets on the sides where i run a string to adjust the leach. The shape is still not great, altho it improved a lot with the leach adjustments it still has excess of fabric left and right from the middle, maybe caused by the remaining of the middle batten. It seems to work fine, as when it is trimmed the extra fabric folds into the inside of the sail, keeping the outside in good’ish shape.
I think the kites would be better shaped with a more flexible yard that would follow better they’re original shape, but haven’t tried it yet.

There’s more information and videos links in Proud Mary thread, under general.

I’m keen to make a new sail out of a big pollytarp I already have.
I think the cut of the sail should be simply a triangle with a rounded leading edge, my question is rounded by how much?
So far i couldn’t get any information about the cut of this kind of Gibbons sails without spars.

Anyone has any idea or info on this subject?

Thanks

I think the book by gary dierking says the sail is basically flat. So you put the yard on the sail and bend it like a bow. How much you bend it is of course important. Unlike garys rig you dont have a boom to tension. So i would look how much your current setup bends in heavy wind and go with that. That way in lighter wind the sail will have some curve.
-Thomas

tdem - 10 June 2013 03:08 AM

I think the book by gary dierking says the sail is basically flat. So you put the yard on the sail and bend it like a bow. How much you bend it is of course important. Unlike garys rig you dont have a boom to tension. So i would look how much your current setup bends in heavy wind and go with that. That way in lighter wind the sail will have some curve.
-Thomas

Thanks Thomas, I failed to mention an important detail;
I do need shape in the sail, just as in a traditional sail. As you mention, I can’t rely on tension to shape it, like in windsurfers or Gibbon/Dierking rigs. My yard is aluminum and does bend very little. (it is because of the wide angle lens that it looks curved in the videos)

I did have problems with too flat of a sail once, before i adjusted it as I could.

I did go thru Gary’s book, witch is great, but, in this case, I couldn’t find a solution in there. I think this is a very easy sail cut, but because of Gary’s better (more efficient) sails are favored, it isn’t very used, and there’snot much information about it.

Thanks