Subject: Re: [baidarka] Skinboats Rule!
From: Peter Chopelas (pac@premier1.net)
Date: Wed Oct 17 2001 - 00:49:08 EDT
Phill wrote:
...I frequently paddle with a bunch of friends who have rec boats, and they
have difficulty
keeping up in flat conditions, but pull away easily when it's rough. Anybody
got any boat modification ideas that might help (I'm paddling an 18" wide
West Greenlander)?
SK magazine did some tank tests a number of years ago and it was found that
the lowest drag hull in calm water was not the lowest in rough water, also the
one with the lowest high speed drag, was NOT the one with the lowest cruising
speed drag. I should think that the cruising condition should be the major
consideration since you only go fast in short bursts in a recreational kayak.
Though I never made a side by side comparison of the two types, the general
feeling by knowledgeable people is the Aleut biadarka is superior for all
conditions, especially rough and windy ones, than the Greenland style designs.
My own investigations and limited experience confirm this impression.
This is also consistent with the various design features. Since the biadarka
has a much lower profile at the bow and stern than a Greenland, cross winds
affect it much less, as do breaking broadside waves. The biadarka's rounder
hull profile below the water line give it much less wetted area, therefor much
less skin friction drag. Also I suspect the smother lines and general plan
from shape of the biadarka are better behaved in rough or confused seas.
I have also heard from reliable sources that the bow and stern design of a
Greenland style will knock you around in rough conditions. Which makes sense
since the center of bouncy on a Greenland bow and stern changes radically as
they dive and rise out of the water as compared to a biadarka. Also the
biadark bow and stern gives you much longer water line length, giving you a
higher top speed, and the finer lower bow piece will penetrate breakers much
better than a Greenland bow. The biadarka stern is reportedly much better at
preventing broaching, and it takes better advantage of the wave energy with
following seas, pushing you along more efficiently.
The ridged fore deck, along with the top bow plate, of the biadarka keeps you
noticeably dryer since splashes are defected away, and when the bow does
penetrate a wave, the water will shed to either side usually before it reaches
the coaming.
Reportedly, the use of more, but lighter stringers and frames, results is a
more flexible, yet still very durable, frame. This feature is reported to
make rough water handling much better, kind of like a suspension on a car,
allowing you better control. I would also say this kind of frame is more
fail-safe, if a single member breaks the frame is not seriously compromised
since the redundancy of the multiple chines prevent hull failure.
The biadarka also has much more internal storage volume than the same length
and width Greenlander, yet it does not appear to weigh any more.
I think it is interesting to note that despite all these performance
advantages of the Aleut biadarka, most commercial manufacturers still copy the
lines of the Greenland hull. And I have to admit that the Greenland hull,
with it's slim profile and sleek bow and stern lines is much more attractive
than the homely biadarka. For mass produced kayaks this is probably a more
important consideration than actual performance, you will not stay in business
long if you can not get your product off the show room floor.
The best of the factory boats actually trys to balance these features, sleek
and sexy looks, with below water line features that still perform well. More
recently many of the manufacturers in the Puget Sound area have been
incorporating Aleut design features in their more recent models then they have
in the past, with noticeable improvements in performance. Imagine that, those
primitive little Eskimos actually knowing more about kayak design than modern
armchair-desk jockey designers.
The really sharply raked and pointy Greenland bow looks really slick but it
has few performance advantages to recommend it. I think the reason for this
bow had to do with hunting requirements for fast landings on icefloes, not
exactly high priority considerations for recreational kayakers.
Bill Low (of Willowkayaks) has "modernized" the traditional bifed biadarka bow
so the open jaw is closed off, improving the looks immensely. I think he did
so without losing any of the performance advantages of the traditional design.
And it is easier to make, and stronger too.
With modern fabrics, adhesives and lashing material, I think a modern skin on
frame biadarka is probably one of the lightest, fastest, and most controllable
kayaks you can get. They will typically weigh half as much as hard-shell
kayak, be just as durable, and have superior performance. It is most
definitely the most structurally efficient way to build. Curious that no one
makes a modern skin on frame production kayak using composite frames [I am not
counting the folders here, all the folding hardware makes them too heavy and
expensive).
So, consider the Aleut biadarka, you and most of your hard shell friends will
likely be quite surprised.
Peter
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