Re: [Paddlewise] Stability

My responses on this have largely been pushed by advertising hype I  
read and conversations I hear. It is quite common to hear something  
to effect of "With it's AAAA chine this boat has XXXX stability." or  
"I paddled X hard chine boat and Y soft chine boat and the soft chine  
boat was much more ZZZZ". My goal is for people to take these broad  
sweeping statements with a grain of salt. They usually completely  
ignore important design characteristics that are much more important.

It is possible to design a waterplane with stability considerations  
in mind. I suspect John does, as do I. Cross sectional shape is also  
an important design parameter which effects the apparent stability of  
a boat, and we both consider it as we design. But, when people  
compare the stability of the chined boat and the round bottomed boat,  
there is a sad tendency to attribute all the apparent performance  
differences to the most apparent design differences.  Boat X and Y  
may have quite different waterline widths and lengths. One may be  
heavily rockered and the other with a straight keel. One has a high  
seat the other a low one. There are lots of characteristics effecting  
the stability, yet people tend to focus on chines for some reason.

For marketers trying to sell boats, this is really convenient.  
Talking about "hard chines" or "multi-chined" (an almost completely  
irrelevant term) is a nice strategy to make purchasers feel like they  
are in the know about esoteric design terms - "Oh, yes, hard-chined,  
yea, that's good, yes mm-hm." It is obscure enough that non-kayakers  
don't know what it is, but a quick lesson makes it easy to recognize.  
And then the marketer can quickly attach any attribute they want to  
the chine, depending on who they are trying to sell to, and nobody  
really knows enough to argue with them.

If I say my hard-chined boat has good initial stability because of  
the chines, as long as I made the boat wide enough to feel stable to  
the uninformed, they will think that I am a genius in my subtle use  
of good chine configuration and never notice that all I did was make  
the boat wide.

There are lots of good reasons to go with hard chines or a round  
bottom. Some of them relate to stability. But most of the other  
reasons are hard for an uninformed paddler to detect on a pond during  
a 2 minute paddle at a local demo day. People are able to get a quick  
feel for the stability comfort level, so for a lazy sales rep, who  
also may not know that much about kayak design, talking about chine  
shape is an easy way to talk about the design. Unfortunately, people  
give the sales rep. too much credence and keep repeating what he told  
them.

Next time a sales rep says "The chine shape of this boat gives it  
good initial stability." say to him: "Chines have nothing to do with  
initial stability. The shape of the waterplane is more important. "  
and see what he says.

On May 14, 2005, at 8:15 AM, John Winters wrote:
>
>
>> And as a practical matter most kayaks have fairly similar water  
>> plane shapes, what changes most
>> significantly is the waterline width.
>>
>
> Does any of this matter to paddlers? I don't know because I don't  
> know how accurately paddlers can detect differences in stability.  
> From a design standpoint a boat is composed of many small things as  
> well as a few large things melded together to create a distinct  
> boat. I recall Matt telling me once how he tweaked and tweaked his  
> designs to reach what he considered the right boat. I bet some  
> people would say he was just nit-picking but if you talk to the  
> people who own his boats you will get a much different response. I  
> suspect the same of Nick's boats and their owners.
>
> The real question is "Does all this matter here at Paddlewise, in  
> the Nit-picking capital of paddle sport?    :-)
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