David,
I was in the same boat. I decided to build a shortened Great Auk, like Nick discusses in the back of his book. I shortened the length using non proportional spacing and the boat came out just a hair under 14 feet. My son weighs 95 lbs, I weigh 210 and both of us can paddle the boat very well. He does seem to sit just a bit low, but he paddles it just fine. I also added a skeg to improve the tracking for him, and I am very pleased with the results. I took it out on a paddle with the South Sound Wooden Kayak Club last weekend and had no problem keeping up with everyone else in their full sizers. There's a picture of the boat on their website. It's not shiny like the others 'cause there is no varnish on it yet, just the final unsanded fill coat.
Mark

: My 8 year old daughter is having a great deal of fun "helping" me
: finish a Spring Run. And, being a good Dad, I'm contemplating whether to
: try my hand at building a smaller kayak for her once the Spring Run is
: finished.