From: kork@imagelan.com (Kirk Olsen)
Message-Id: <9503091349.AA23637@imagelan.com>
Subject: Bifid bows (fwd)
To: baidarka@imagelan.com
Date: Thu, 9 Mar 95 8:49:34 EST
> From: mark_stirling@mindlink.bc.ca (Mark Stirling)
>
> I find it interesting that George Dyson notes the "twig" across the
> bow to be baleen - a strong elastic material. This would in fact strengthen
> the bow piece cantilever style from wave pressure on top when plunging into
> waves.
> It is important to consider bow design with the conditions that
> determine it. I have paddled a wood boat of narrow design on the west coast
> for a number of years and this boat has a low volume bow.
I think the shape of the bow is critical with regard to what will happen
when you paddle into a wave. A thin verticle bow will slice into the
wave. A triangular cross-section will try and pop back to the surface.
I think the bow on the Necky kayaks is an extreme example of the
triangular bow design. The bifid bow is an interesting mix of designs.
The lower jaw looks like it will slice into the wave and the upper
jaw will try to lift up out of the wave. (now if I could just finish
my bifid bowed kayak I could verify this)
> With a following
> sea I have had kelp get caught on deck and had to back out. A bifid bow
> would be no more likely to catch than a solid one if bow volume is low.
I think cross-sectional design of the bow could make a big difference here.
Even with comparable bow volumes. I have a marathon flatwater racing
canoe with a 16 inch verticle stem that slices right through waves. I
think the addition of some hull flare would make a monumental difference
in how that boat paddles in waves, as it is a wave of the same size as
the bow will usually come into the boat.
> The problem of bow design is not simple. I have asked a number of
> modern lower mainland Vancouver and also Victoria commercial kayak designers
> to suggest how I could improve the bow and stern design of my own boat so it
> would not dive into waves (perling), broach less and I received a variety
> of answers. Some go for a high volume bow, the problem here is that too
> much volume stops you dead and you lose forward momentum but get a dry ride.
> A low volume bow cuts through the wave but can dig in and broach more
> easily and also tends to give a wet ride.
> The illustrations I have seen of baidarka being paddled show a wet
> ride. The bifid bow seems to be a compromise between getting adequate lift
> at the bow and still preserving the momentum. The only time trouble with
> catching things really happens is coming into a kelp bed with a following
> sea and this happens whether the bow is split or not!