Ben wrote:

Thank you sir, for your reply. I have been studying your many articles, thank you for posting so much information for us all. I was simply curious if a twin keel design changed things any. Thanks again!

No need to sir me mate!

I am proud to let you know that in Norway we have dozens of words describing all sorts of (mostly foul) weather, and scores of words describing different sorts of boats  -  but we have no operational word for ‘sir’.  Somehow, we still cope...

Arne

I guess you ask about this  because you want to design a JR and want to find a useful position for the sail’s CE. In cases where I know the CE of the existing rig, I rather use that as a reference and then correct it , using these home-made “rules” (assuming that I make the junk sail with cambered panels and with the max camber point about 35% of the chord from the luff):

• If the boat balances nicely  with the Bm rig (sloop), I position the JR’s CE 3 – 5%  of the WL further aft.
• If the boat have more weather helm than I like (Bm sloop), then I put the CE of the JR on the same position as for the original rig.
• If the boat has lee helm with the Bm sloop rig, I move the new CE of the JR up to 10% aft of the original place.

Those who made that twin-keeler already have done the brainwork (or cutting and trying) for us, so we save ourselves an unnecessary headache by not trying to do it again..

Cheers,
Arne