10% is the general rule. You need to modify your stem forms to match.

: Several years ago I cut out the forms for a 17'-6"" strip-built
: kayak. Life got in the way and the project was shelved. I'm considering
: reviving it but, since I've already built a 17'-6" Pygmy Coho, I'd
: now like a considerably shorter day boat.

: So, how much would you experts feel I could shorten (either in inches or
: percentage) my station spacing and use the existing forms without
: significantly degrading performance? I can always start over with another
: design, but want to consider my options first.

: Thanks,

: Glenn