Kris,

First of all thanks for that nice modified wireframe model, it looks pretty cool. You beat me to the punch, I don't have time until this weekend. Very nice.

: Someone correct me if I'm wrong here, but Kaper would have NO WAY to catch
: anything of this sort as it is doing math on several
: dimensional/spatial/coefficient inputs and is NOT doing a flow analysis of
: the hull. As such, it must assume the hull follows some basic conventions
: of design.

I downloaded the KAPER spreadsheet and yes it takes a number of simplified parameters, not the hull shape, that makes one wonder how accurate this can be. It may very well be OK but the subtleties of the design are entered in a rough way. And maybe that's all that matters. In the case of my design I suppose we would put in a high flare factor and for your modified model a lower one ore zero. So in that way it can actually be accounted for.

: I seriously doubt it on a displacement hull. Bow wave is a result of the bow
: interaction with the water, not something to match the design to. If you
: model to that you'll just get a shape that creates turbulence in the flow
: - in a bad spot for it.

Just because I can't use KAPER to prove you are wrong does not mean that you are right. Or that I am for that matter. Your argument that a sharp chine leads to turbulance is not convincing to me. It is just your intuition. If KAPER can't resolve it we need to find fluid dynamics software but frankly that is more than what I want to take on now.

: If you'd rather look at it as your kayak design vs. mine sort of thing, my
: 19' hard chine hull with rather conventional chine terminations is a LOT
: faster than a 15' SOT. It's as fast or faster than my QCC700 (a VERY
: efficient design by someone WAY out of my league). Granted the SOF has
: 4" more LWL, and is 2" narrower - but it also sits depper in the
: water, is a hard chined SOF, and was designed and built by an amateur
: (using proven design elements - reconfigured to meet my design intent).

For pure speed you would indeed want a QCC type of shape. BTW not all SOTs are created equal. MIne is the Wilderness Systems Freedom, one of the fastest ones around. It is relatively fast but I would have to do the compariaon again, it has been a while.

A sharp chine has some other advantages like cutting through waves without much pitch and tracking without much yaw. This will improve the efficiency in typical ocean water. So the KAPER numbers are only marginally relevant because it is for flatwater without yaw caused by the paddler, I just don't want them to be horrible.

: Your logic on more conventional configurations here is fatally flawed.

You don't bring in any convincing arguments other than your experience. I am really interested in the physics and modeling and would like to know how this works out mathematically not intuitively.

: A. Out of curiousity, what
: specifically are these "other types" you are paddling against?

Mostly I paddle "with" not "against" - it's with a group who call themselves the Old Farts ;-) (with pride, no kidding). But sometimes with strong kayakers who are on the other side of the spectrum. Up against the waves I can beat them but not in quartering waves, I think the boxy stern works against me.

: B. How many other kayaks have you paddled?

Only my own, and a CD one time I believe the Extreme.

: Don't look at them as being MY comments - or even as critcism (a good word
: that gets a bad rap). I'm just pointing out useful info I've come across
: and what I see looking at a few thousand successful hull designs!

You may very well be right but you seem pretty religious about it. The two different designs that we are talking about basically only differ in flare so how different can it be. If there are differences, each shape is probably better at something. Maybe I will build one your way too, in fact I would like to have one at my new workplace which is right on the water.

Henk