Yep, hard to tell those measurements between boats when you can't be there to witness actual degree of rocker to gunnel design. Mike, if you want a workable fishbox and have limited under seat space, check out the plastic models that Holiday Market in Mount Vernon has. They are (approx) 42" wide by 18"long by 12" deep. When I had my 14' wood boat this box slid perfectly under the passenger seat. They're made out of a grippy textured plastic that won't slide around. I couldn't have designed anything to fit better in my boat, just dumb luck.