Re: [Paddlewise] Hard chined hulls

Robert Warren wrote:

> In Derek Hutchinson's "complete book of Sea Kayaking",
> he describes different hull designs, and their characteristics.
> On the subject of hard chined hull shapes, the description has
> me a bit puzzled, because,  it is contrary to what a lot of
> kayak owners say about their hard chined kayaks.
> (From Derek Hutchinsons book "Complete book of Sea Kayaking")
> "The V-shaped or chine hull, the traditional shape of many
> Eskimo kayaks, gives directional stability as long as the amount
> of rocker is not excessive. However, with such a hull it is
> unfortunately almost impossible to maintain fast forward speeds
> because as the speed increases the boat tends to plane on the
> flat chines. The kayak thus retards itself on its own bow wave".
>

If the hull form is such (and I'm not sure what this exactly is!) that the hull
planes it has the effect of :
1.  Decreasing the waterline length and max hull speed is a function of
waterline length, and
2.  Decreasing wetted surface which will lower the amount of energy needed to
maintain the same speed.

I'm not sure, for the speeds we're talking here, how these two things
interrelate.  I doubt that the hull gets up on a plane like a speed boat does.
And, I expect the angle of the "V" at the centerline will have an impact also.
But which way, again I don't know.

Designers can probably throw a lot more light on the topic.  It's a good
question and I sure would like to hear the discussion.

John Blackburn

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