Bryan,
Thanks for the feedback. Your target Cp helped me monitor the effects of my changes much better. I actually ended up at .561 which seemed to optimize right on 4.5 knots. I think realistically 4-4.5 knots will be my typical paddle speed. I shared your concern about diving with the low front end volume but could not find a solution that did not compromise speed. You inspired me to try harder and I was successful. I looked at the Taran after I made the modifications, maybe I need to add some more volume. You may have just inspired another project. The Epic 18 was used a little at the beginning of my design but I departed a long ways from it. I actually like the Stellar 18 as a fast all around type of boat and have tried to incorporate some design from it. I did tame the rocker a bit, I was struggling with it also. I posted the new design on the kayakfoundry forum. Any more suggestions would be appreciated. I think your encouragement and advice helped a lot.
Scott

It looks like it's going to be fast and the numbers look good at 4
: and 4.5 knots. You'll get a little less resistance at 4 knots if
: you get your Cp down to .53, but you're going to lose some
: volume in the ends. If you're trying for 5 knots, you might try
: getting the Cp up to around .56 or so to see if you gain
: efficiency. It's pretty narrow upfront, so it's going to dive in
: waves and not come up quickly, which could slow you down. Get
: some flare up there above the waterline to help the front stay
: dry and keep up some speed. I'd consider changing the shape of
: the bow to something more similar to the Rockpool Taran
: (http://www.rockpoolkayaks.com/taran.php) to get a touch more
: waterline and more volume up there.

: I'm not sure I like the look of the rocker forward the cockpit. It
: just doesn't look right to me. I can't put my finger on what I
: don't like about it, but I'd mess around with it a bit more.

: My guess is that it's not going to have a high primary stability,
: but have good secondary.

: The lines for Epic's 18X Sport are in the October 2008 issue of Sea
: Kayaker. I suggest looking at them a bit if you haven't already.