: My question for those of you who have built, or are building a foam seat ----
: what length (front to back) did you end up with, in order to get
: comfortable support?

I've settled on a total length of 20", including about 2" at the back of the seat for backrest support. That gives me enough forward support for my thighs. I'm 6'1" and 210lbs.

12" is way too short, one of the reasons Sealine has come out with that new inflatable thigh support reviewed in the latest issue of Sea Kayaker.