Date: Fri, 16 Jan 1998 08:53:34 -0600
From: Wolfgang Brinck <wolfgang.brinck@hksystems.com>
To: baidarka@lists.intelenet.net
Subject: Re: bow cross-section
Ben Collman wrote:
>
> >will do, but I believe that this has more to do with hull shape - the
> >tendency
> >of the boat to stay parallel to the surface of the water, i.e. the face
> >of
> >the wave, and dynamic lift - lift provided by the hull as it moves
> >forward in
> >the water and not by the few square inches of flat surface at the bow.
> >
> >Wolfgang
>
> My experience is mostly with commercial fishing boats - displacement and
> planing- and also with outboard powered skiffs.
>
> It is the cross sectional surface area which gives that dynamic lift, yes?
> Unless you're travelling awfully damned fast, a thin knife-edge cross
> section won't give very much support. It will give some support and help to
> reduce pounding as you crest waves, however. To give the support needed to
> keep the bow of the boat from burying itself in waves requires some belly
> to the boat - cross-sectional area. I am reminded of this when I see small
> Snowballs, a hull design with a lot of flare to the bow and not much belly.
> They really submarine into the waves and as a result most of them have
> plywood "eyes" covering all but a pupil of their front windows. The owners
> apparently tired of replacing them every time they ran into weather.
>
> Ben Collman
Exactly.
The sharp part of the baidarka hull is strictly near the nose. The hull
following the nose has quite a bit of belly and provides the lift. The
baidarka's cockpit is also farther back of center than in a Greenland
boat.
This means that the nose feels the oncoming wave sooner than in a boat
with a centered cockpit and consequently rises sooner. (Sooner as in
a Greenland kayaker and baidarka operator paddling abreast - the
baidarka's
nose would be farther ahead.
The keelson of the baidarka also rises upward toward the bow and
actually
comes above the water line. I noticed this when plowing into thin ice.
A Greenland kayak plows into the ice since its keelson at the bow is
below
the water line. A baidarka on the other hand climbs up on the ice since
its
keelson at the bow rises above the waterline. In a similar way, a
baidarka
tends to climb up on an oncoming wave due to the configuration and
bouancy
of its hull. But to a paddler paddling, it may well seem that the flat
part
of the nose is doing this work when in fact it's mostly the hull back of
the
nose.
Wolfgang