I had the same question a while ago and ended up creating an Excel spreadsheet to calculate the locations based on paddler weight and desired separation. I'm not sure it will work for you but here's the link.

: Hey,I'm building the Guillimot Double out of Nick Schade's strip-built book.
: It's tons of fun, and going great. I'm just about finished stripping the
: hull. My next step is the deck, and I'm not sure where to put the two
: cockpits. I've looked everywhere in the book for specific locations but
: haven't found them. Has anyone built this one and have an answer?

: thanks