My first thought about the failure to weathercock is that in order for that sail to turn, it has to have some resistance to turn against.  It might be that with the heavy lee helm, the forces at work make it easier to turn the boat than the sail.

In any case, that lee helm is frightening when it happens.  I once nearly T-boned a $2 million yacht with 17' foot cat ketch because the mainsheet (forward sail) stuck but the mizzen ran out as it should.  I actually snapped the tiller extension trying to bring her around.  A scratch on that yacht would have cost me more than my house.  I bought collision insurance the next day.

Thank you, Annie. A picture of the boat with sail up is in my album.

Edward, the mastposition had been changed to aft in order to have the sail center where it should be.

Why my sail did not weathercock - I do not know. As you both, Edward and Slieve, had no problems with the balance of 33% I thought my sail would be right too.

Maybe the combination with the leehelm led to this phenomen.

Some interesting thoughts have been written here:

http://www.junkrigassociation.org/general_forum/1348650?mlpg=2#1348650

You look to have built a beautiful boat there, Bert.  I'm sorry to hear you are having some issues with your rig.  Why don't you put your sail plan drawings in your albums so that the split junk aficionados can play around with them and see if they can work out what the issue is? 

Weathercocking: Yes, it seemed to me that the sail did not want to go into the wind. Weather was very calm (1-2bft).

When the wind increased a little bit, the sail even came in close to the centerline of the boat.

When the wind became a little bit stronger, the boat heeled due to the increased pressure, now more from the side, and rushed away. Normally one would steer now to windward but no way to get around, no reaction when letting the sheets go, the sail did not swing out. Only 2 possibilities left: jibing or taking the sail down. My first trial was on a river near the waterfront, jibing was not more possible, thanks to the junkrig the sail came down in less than a second and saved the boat.

As I could not make any changes last year because the jibs and main were fixed together (sewn at the lower end of the toppanel), the only way to reduce leehelm was to move the whole unit back. Leehelm was a little bit reduced but still severe. When the wind got stronger tacking was still not possible. Maybe this would not be an issue on another boat (Farthing has a long keel and holds course well, secondary she was not fully loaded which means she has a very sensible trim = stem comes out of the water, stern sinks and so the CLR moves aft). I decided to have a good deal of weatherhelm to be safe, so I reduced the balance between jib and main. The lead between CE and CLR is now at 15% of the waterline, which seems to be ok for a longkeeled boat, if I am not wrong. For the next trial I did not join the "new" jibs and main, they will be fixed together when all is like I prefer.

Hi all,

that's my first posting here :-)

I own a Farthing by MacNaughton and gave her a split junkrig. I followed the descriptions of Slieve but changed it to a rig like amina (1 toppanel). Balance was 33%, sail centre at the same position as the flat designed sail by the Designer.

I encountered strong leehelm (very dangerous, because no tacking possible). It seems as if the cambered sail has its centre of effort more forward than the flat sail. I just finished cutting the jibs at the leek, balance is now 25%. Because the splitrig can't be moved forward or aft, it is all trial and error. Trial sail will be in june. Hope it will fit!

By the way: My impression was that the sail wasn't willing to act as a weathervane as desired. The camber forward seems to balance the "main" sail.

Best wishes to all!

Bert