Ghislain,

For what it's worth I used Ross Leidy's Kayak Forum to design a 13' kids kayak which I started building five weeks ago. (http://www.blueheronkayaks.com/kayak/index.html)

Kayak Forum is very easy to use and one of it's nice features is that it can be used to print out the station forms. The program starts with a standard shape which you can then alter by moving various contact points. To start your design you enter general information around paddler weight, etcetera and then work to match up the design displacement with the required displacement. The program takes a little getting used to, but there is good information in the help and on the kayak forum.

The boat I'm building is 13' by 21" with a design displacement of 160lbs (30lb for boat, 15 lbs for gear, 115 lbs for kid.) My objective is a boat that a small paddler can use that performs in a similar way to my other touring boats. What I was particularly interested in was tracking and speed with low windage.

Good luck finding the right boat for you.

Ken