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Re: S&G: Importing models into FreeShip *Pic*
By:Kris Buttermore
Date: 12/5/2007, 12:12 pm

: I remember Kris, we got into this discussion before. And my answer is still
: the same. However maybe I will try a model the way you sescribe it, run it
: again and see what Kaper says.

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.

Have you ever taken the measurements from the model yourself and entered them manually vs. letting the software do it? If you do, you'll see exactly what goes in, and more importantly what doesn't, and how it will not see your unconventional chine configuration or be able to alter it's drag predictions if you change them (unless other measurements change in the re-design process).

: Prove that to me first.

Just draw the buttock lines (and read Winters on how water flow along the hull closely follows them).

: The chine looks like it follows the bow wave of a
: boat. Could it be that this may be helpful?

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.

There is more to a decent cutwater than a fine entry too. It needs to guide the water along and under the hull. Chine configuration (even totally smooth/blended chines) plays no small role here. A very common misconception is that the water is pushed out to the side of the kayak as it moves - but very little water actually does this - and what does wastes energy (think snow plow vs ski). What you see in the waves is energy moving away through the water, not actual water movement (smaller waves meaning less energy going to make waves). Most water flows under (roughly following the buttock lines). Your chines do not encourage this flow to be along smooth contours. They would cause the flow to alter course as it moves along them. Result: turbulence and added drag.

: Your word is as good as mine I
: think.

OK, sure, but this isn't about you or I - it's about very basic hydrodynamics and performance on the water (and centuries of refinement verified by modern calculations).

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).

: Besides, maybe I was underrepresenting my current yak, it beats the
: crap out of most other boats going up against the waves. Especially since
: it cuts so nicely through the waves, something that you will not see with
: the bows that you desribe.

What you're seeing probably has to do with the motor (or company you keep). Definitely not the chines. Even if they are MUCH less detrimental than they look, at best it would be a wash - but I don't see how even that's possible.

Your logic on more conventional configurations here is fatally flawed. There is no reason you will not get a bow that cuts nicely through chop doing what I (and thousands of other kayaks) suggest. If anything, it would improve this. At this point I have to wonder:

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

B. How many other kayaks have you paddled? How many were fast narrow designs with good wave cutting bows - like EPIC, QCC, Surf Skis, or any number of racing kayaks?

: But I appreciate your comments and I am not automatically discarding your
: arguments. Thanks for the feedback,

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!

For fun, here's your current effort, re-chined more conventionally (and not placed optimally, just a generalization that follows your original lines as closely as possible):

Messages In This Thread

S&G: Importing models into FreeShip
HenkA -- 12/2/2007, 3:02 am
Re: S&G: Importing models into FreeShip *LINK* *Pic*
Bryan Hansel -- 12/6/2007, 11:12 pm
Re: S&G: Importing models into FreeShip
HenkA -- 12/7/2007, 11:53 am
Re: S&G: Importing models into FreeShip
Bryan Hansel -- 12/7/2007, 9:00 pm
Re: S&G: Importing models into FreeShip
Toni V -- 12/7/2007, 1:21 pm
Re: S&G: Importing models into FreeShip
Acors -- 12/3/2007, 10:48 am
Re: S&G: Importing models into FreeShip
HenkA -- 12/6/2007, 8:55 pm
Re: S&G: Importing models into FreeShip
Acors -- 12/7/2007, 9:55 am
Re: S&G: Importing models into FreeShip
HenkA -- 12/7/2007, 12:13 pm
Re: S&G: Importing models into FreeShip
Acors -- 12/7/2007, 8:39 pm
Re: S&G: Importing models into FreeShip
HenkA -- 12/9/2007, 2:28 pm
Re: S&G: Importing models into FreeShip
AaronH -- 12/7/2007, 10:23 am
Re: S&G: Importing models into FreeShip
Acors -- 12/7/2007, 8:31 pm
Re: S&G: Importing models into FreeShip
AaronH -- 12/5/2007, 3:18 pm
Re: S&G: Importing models into FreeShip
Acors -- 12/6/2007, 11:48 am
Re: S&G: Importing models into FreeShip
AaronH -- 12/6/2007, 2:55 pm
Re: S&G: Importing models into FreeShip
Acors -- 12/7/2007, 9:29 am
Re: S&G: Importing models into FreeShip
HenkA -- 12/3/2007, 4:07 pm
Re: S&G: Importing models into FreeShip
Acors -- 12/4/2007, 2:27 pm
Re: S&G: Importing models into FreeShip
HenkA -- 12/7/2007, 12:08 pm
Re: S&G: Importing models into FreeShip
Bryan Hansel -- 12/2/2007, 4:27 pm
Re: S&G: Importing models into FreeShip
HenkA -- 12/2/2007, 6:20 pm
Re: S&G: Importing models into FreeShip
HenkA -- 12/2/2007, 10:06 pm
Re: S&G: Importing models into FreeShip
Toni V -- 12/3/2007, 2:24 am
Re: S&G: Importing models into FreeShip
HenkA -- 12/3/2007, 10:03 pm
Re: S&G: Importing models into FreeShip *LINK* *Pic*
Kris Buttermore -- 12/4/2007, 5:27 pm
Re: S&G: Importing models into FreeShip
HenkA -- 12/4/2007, 6:25 pm
Re: S&G: Importing models into FreeShip *Pic*
Kris Buttermore -- 12/5/2007, 12:12 pm
Re: S&G: Importing models into FreeShip
HenkA -- 12/6/2007, 3:14 am
Re: S&G: Importing models into FreeShip
Bryan Hansel -- 12/6/2007, 9:56 pm
Re: S&G: Importing models into FreeShip
Kris Buttermore -- 12/6/2007, 11:21 am
Re: S&G: Importing models into FreeShip
Robert McMurray -- 12/5/2007, 3:14 pm
Re: S&G: Importing models into FreeShip *Pic*
Kris Buttermore -- 12/5/2007, 4:59 pm
Re: S&G: Importing models into FreeShip
HenkA -- 12/6/2007, 3:20 am
Re: S&G: Importing models into FreeShip
Kris Buttermore -- 12/6/2007, 10:02 am
Re: S&G: Importing models into FreeShip
Bryan Hansel -- 12/5/2007, 1:17 pm
Re: S&G: Importing models into FreeShip *LINK*
Toni V -- 12/5/2007, 1:48 pm
Re: S&G: Importing models into FreeShip *Pic*
Kris Buttermore -- 12/5/2007, 5:21 pm
Re: S&G: Importing models into FreeShip *LINK* *Pic*
Toni V -- 12/6/2007, 4:07 am
Re: S&G: Importing models into FreeShip *Pic*
Bryan Hansel -- 12/6/2007, 10:24 pm
Re: S&G: Importing models into FreeShip
Toni V -- 12/7/2007, 5:35 am
Re: S&G: Importing models into FreeShip
Bryan Hansel -- 12/7/2007, 9:10 pm
Re: S&G: Importing models into FreeShip
Kris Buttermore -- 12/6/2007, 9:49 am
Re: S&G: Importing models into FreeShip *Pic*
Bryan Hansel -- 12/5/2007, 2:17 pm
Re: S&G: Importing models into FreeShip
TOM RAYMOND -- 12/5/2007, 2:31 pm
Re: S&G: Importing models into FreeShip
Bryan Hansel -- 12/3/2007, 10:22 am
Re: S&G: Importing models into FreeShip
Toni V -- 12/3/2007, 11:18 am
Re: S&G: Importing models into FreeShip
HenkA -- 12/3/2007, 3:55 pm
Re: S&G: Importing models into FreeShip
HenkA -- 12/3/2007, 3:43 am
Re: FreeShip... a fast kayak? *LINK*
Toni V -- 12/3/2007, 7:05 am
Re: S&G: Importing models into FreeShip
Bryan Hansel -- 12/2/2007, 10:31 pm
Re: S&G: Importing models into FreeShip
HenkA -- 12/2/2007, 10:41 pm
Re: S&G: Importing models into FreeShip
Toni V -- 12/2/2007, 5:47 am
Re: S&G: Importing models into FreeShip
HenkA -- 12/2/2007, 2:23 pm
Re: S&G: Importing models into FreeShip
Toni V -- 12/2/2007, 3:36 pm
Re: S&G: Importing models into FreeShip
mike allen -- 12/2/2007, 5:04 am
Re: S&G: Importing models into FreeShip
HenkA -- 12/2/2007, 3:16 pm
Re: S&G: Importing models into FreeShip
mike allen -- 12/2/2007, 4:09 pm
Re: S&G: Importing models into FreeShip
HenkA -- 12/2/2007, 2:16 pm
Re: S&G: Importing models into FreeShip
mike allen -- 12/2/2007, 3:52 pm
Re: S&G: Importing models into FreeShip
mike allen -- 12/2/2007, 5:12 am
Re: S&G: Importing models into FreeShip
HenkA -- 12/2/2007, 2:07 pm
Re: S&G: Importing models into FreeShip
mike allen -- 12/2/2007, 4:03 pm