: 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?

From an earlier post, below is how I determined length. BTW, overwidth blocks of foam are expensive--and worth every penny.

The proper angle of your seat surface is determined by your thigh as you sit with your feet positioned on the pegs. So, one thing I would add to Vaclav's great instructions is, I sat on a thin pad in the boat with my feet on the pegs, then slid a 3-inch block of foam backwards until it just touched my thigh. This defined how long the seat should be from the cheek cups to the forward edge. Everything else just as he says and you can't go wrong, I promise.

http://www.oneoceankayaks.com/Wshophtm/kayakseat18a.htm