Subject: baidarka Baidarka speed comparisons - actual and modelled
From: Eddy, Andrew (Andrew.Eddy@foodscience.afisc.csiro.au)
Date: Tue Oct 17 2000 - 22:18:26 EDT
A friend and I have built Eric Schade's stitch and glue plywood Shearwater
Baidarka design.
See Part 1 of the article on building these kayaks at
http://www.nswseakayaker.asn.au/mag/43/baidarka.html
In the last few weeks, we have been testing them in various conditions and
found them to be (pardon the one-eyed testament) the _best_ kayaks that
either of us have ever paddled. The performance and handling in both flat
water and rough conditions has been outstanding.
Over the last few days, I have taken offsets from these two kayaks (mine is
built according to the plans at 17'3" by 21", my friend's is a 6%
photoreduction at 16' by 19.75") and put them into some hydrostatics
software and the results from this into John Winters' Kaper program.
I have been able to compare several published sets of resistance for these
groups of kayak:
* several production sea kayaks of around 17' at a displacement of 250#
* several of John Winters' designs, as made by QCC kayaks at their design
displacements (varying from 180 to 320#
* our two Shearwater Baidarkas at their actual displacements with ourselves
and various other people in them
* a museum specimen baidarka - MAE 593-76 (19'1" by 17")
Some of the things to keep in mind when reading the results below are:
* baidarkas in general might fit John Winters' model at all
* some of the "faster than" comparisons are within the 5% tolerance of
Winters' model and might actually be "equal to"
* some of the displacements are not exactly comparable (see above) and I
have made no adjustments
So, what do we see?
Firstly, there are two distinct sets of curves:
* there are the production sea kayaks (which includes the Pygmy Coho)
* there are the baidarkas and John Winters' designs
They are that distinct! Note that Winters' designs are not baidarkas. They
_look_ quite ordinary, but their performance predictions have them in a
distinctly lower resistance band than the run-of the mill, at cruising
speeds and as much as 35% less resistance at sprint speeds.
My friend's Shearwater Baidarka is the fastest kayak of all at cruising
effort levels and mine is equal to MAE! Even when my friend's kayak is
vastly overloaded (with a 200# paddler instead of the 90 to 120# which it is
designed for) it is still an astoundingly fast kayak, only equalled by one
of John Winters' designs and none of the production kayaks.
MAE is fastest at high effort levels - up to 2 knots faster than typical
fibreglass sea kayaks in a flat-out sprint, up to 0.5 knots faster than our
wooden baidarkas and not less than 0.7 knots faster than the Winters
designs.
So far, the only on-water speed trial has my Shearwater Baidarka going about
5% faster than the Coho. The marathon paddler who did this timed comparison
for me (at the LCVCC handicap) complained that he would have gone faster,
except he couldn't reach the bulkhead footrest, he slipped around on the
seat and a few other niggling problems. Performance prediction says that he
should go 12% faster than the Coho and couple of (race-winning!) minutes
faster than his purpose built long-distance flat-water racing kayak. Do you
believe it? I'm not sure.
Meanwhile, does anyone have details of the speed trials conducted by Greg
Barton and Scientific American Frontiers TV in 1991? I would particularly
like to know the relative speeds of Barton in the sprint kayak and the Seda
Glider, compared to the two Shields baidarkas. There was just a hint of this
info in this mailing list in 1995, but no actual comparison.
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