Date: Fri, 10 Mar 1995 13:59:23 -0500
Message-Id: <199503101859.NAA18254@postbox.acs.ohio-state.edu>
To: baidarka@imagelan.com
From: hazel.2@postbox.acs.ohio-state.edu (Paul W Hazel)
Subject: Bifid Bows
About bifid bows and the 'twig':
Late last summer I was able to get out to George's shop and saw the
bifid reconstruction that had been done by a graduate student: it is a
wooden frame with nylon skin _and_ includes replicas of the bone/ivory
"bearings" between the joints.
Naturally I asked the $64,000 question - How big a difference did
the bearings make? George replied to the effect that the coated nylon skin
was so much stiffer than an original skin boat would have been that it was
difficult to see any noticeable difference (George, maybe you could
enlighten us / correct me, here).
Mark wrote that the balleen strip might have served to strengthen
the bifid bow
against waves: I think the reinforcement concept has merit , but from a
different perspective. The impulse imparted to the boat by a wave is
intermittent. While the force of the wave may compress to some extent the
'Y' of the bifid bow, the period before the next wave allows the structure
to rebound. Thus the force on the bow is not constant and the structure
doesn't need to be built to resist that force, just be able to absorb it
through flexion ( many, many times - like a spring.)
However the force of the water acting like a wedge between the two
prongs of the bow would always be present during forward movement of the
boat. Here, I think, would lie the best use of the baleen - to hold the nose
together over time. The baleen would also serve to counter any tendency of
the bow to curl when the boat is drying on the beach. (In which case we have
an example of a device on a boat which has no direct use in terms of
paddling performance - and worse we have no way to verify it)
Nick wrote that he felt the bow was strong enough not to need a
brace, and he may well be right, but I think the reproduction mentioned
above leaves us with the implication that we just don't know. The point to
make here is that unless we want to go bag some sea mammals, or until a more
flexible skin material is developed, we are never going to know exactly how
this thing handled.
The concept of using the 'twig' as a bubbler bears consideration
from another angle as well. If the device actually did produce a fair number
of bubbles, it may have been more useful as a stealth tactic than anything
else. The gentle hissing sound created by the dissipating bubble wake would
help to mask the unnatural sounds of a boat and paddler as he made his final
approach for a kill. Remember here that sound is amplified and carries
considerably underwater - the hiss would carry farther and might sucessfully
imitate the hiss of waves.(This is not an original idea - I'm pretty sure I
read it somewhere, but I don't remember the source.)
My anti-tomato poncho is in place...
Paul Hazel
hazel.2@osu.edu