since you changed the design...you put yourself in the realm of not knowing if you got it right for sure
or not.

I designed my own, and based my cockpit location by about what a similar kayak would have, by eye.

Rather than risking having to re do the coaming etc..i taped the deck on without a coaming...
just the strips glassed with the approximate key hole shape cut. then sat in the boat on a rolled towel to see the balance....also i put it in the pool...then i had my kid sit in it and took a couple pictures from the side...and saw that the stern looked a little higher out of the water than it should be even though the towel test and my own sit in seemed ok.

I ended up lengthening the cockpit aft 6". So by eye I was pretty far off, but no biggee since i did'nt have the coaming done yet.

End result is I got it right by trying different things.. I would think if you do a rolled towel balance test it will be in the ballpark...and then add a couple inches aft with your coaming like i did so you can adjust your seat position a bit more to compensate for error.

http://www.youtube.com/watch?v=2tvNsksPqD4&feature=plcp
https://vimeo.com/19844829

: Thanks...for all the quick responses and great information that all
: of you have sent me on this matter of Buoyancy. To answer all
: your questions...I did stretch the 10' version of the AUK to 11'
: 4''......by evenly spacing out the forms...the lines of the boat
: came out looking great by adding the extra foot or so...I did
: not mess with any of the width....I appreciate the software, the
: formula that was sent, and the idea about using the same
: percentage of boat for the cockpit location...I will use all the
: info that was sent to make the decision on the cockpit......my
: belief is that it was such a small stretch is that using the
: same percentage as to where the 10' cockpit was placed will be
: adequate for the 11'4"
: version.........................Thanks again for all your
: help...................Gordon