Having built a Mystery (20') and designed and built a surfski (21') with Kayak Foundry I found that you have to be really fit to benefit from the long length. If you don't have the power you will go slower with a longer boat with the extra wetted surface.

I would take a look at the E18 -on the Blue Heron site. I think that is a beautiful boat with few if any drawbacks. It's fast especially over long distances.

I once asked Nick about shortening the form spacing on the Mystery and he wasn't enthusiastic due to the work that has to be done to correct related parameters. It's not so simple to lengthen or shorten a design. I guess he can help you with modifications if you go that route but then you might also want to look at the Razor Billed Auk at 19'.

: Thanks all for the sage advice, thoughts and encouragement.

: Paddling out this morning among the porpoises, sea lions, dolphins
: and giant jellyfish, as I was passed by a paddle boarder, I came
: up with this idea:
: Order plans and build Nick's Mystery, (Nick, any thoughts on what
: might soup up the Mystery, that are outside race rules? Stretch
: it to 21'? 22'? I don't race, so it won't be cheating.)

: Once I'm on the water and having a great time with my
: Mystery-variant, and the cedar slivers have worked their way out
: of my hands, I'll consider what to make next, maybe even an
: outrigger.
: Those guys seem to be very quick, 6-7 knots. But why only one
: paddle blade? We walk with two feet, we hold paddles with two
: hands, even outriggers hold their paddles with two hands--but
: only one blade? I asked some outrigger guys one time and they
: looked at me like I was nuts for asking. One guy said someone he
: knew had once tried a double blade but was too slow.

: Another realization I had since yesterday. Which part of a
: (swedeform) kayak should have the greatest draft? (lowest point)
: under me, or just behind me where the widest part is
: (55percent)? If I don't have a clue on that simple aspect--I
: might build a kayak based on my opinions instead of building
: based on actual knowledge and understanding.

: Will