http://www.clcboats.com/forum/5/thread/35254.html

Sadly this idea came out after I was too far into my build to do it this way. I think you could make it work. 

   Hey guys, it says in my plans that the Boom and Yard are identical, however, when I scarfed them up, one of them is around 30" longer.  Is there any reason for this?

Also, why can't I attach the mast thwart knees to the inside of a the inwales and curve them to fit well?  

   One last thing!  I remember reading about a fellow NE Dory builder who did not want the under-thwart flotations and instead went with buoy-like flotation on the inside.  I've tried at length to find these posts, could anybody help me out? 

   The boom and yard most certainly are the same langth -- 108". Measure your shorter one. If it is at least 108", all is well. Just cut and shape them both to that length. If your shorter one is less than 108", you'll have to scarf on another piece (perhaps from the longer one) to bring it up to length. That would be a bit of trouble, but just fine.

   Attaching the mast thwart knees as you suggest might work, but the inside of the inwale is not as strong as the side of the boat and there can be significant lateral forces on the mast thwart when underway in a good breeze. You'd be taking a chance that the designer certainly never contemplated.