Date: Fri, 19 May 1995 16:33:36 -0400 (EDT)
From: Kirk Olsen <kork@imagelan.com>
To: baidarka mailing list <baidarka@imagelan.com>
Subject: Article via Garry Rose.
Message-Id: <Pine.SV4.3.91.950519162650.4672B-100000@baidarka>
The following is the article posted by Garry Rose, rose001@ibm.net, a while=
back. I simply converted it to dos text using Microsoft Word. Hopefully
it doesn't contain any characters that upset email systems on
this list. All questions concerning this article will have to
be answered by Garry. I do not know who the author of the article
is - although they reference paddling in areas that I frequent.
kirk
--------------------------------------------------------
My Bidarka is built of northern white cedar with the exception of
the ribs and they are white ash. The skin is of 26 ounce double
knit nylon acquired through and with much kind help of George
Dyson. That skin is finished with an elastomer called Hypalon.
All lashing are of tarred nylon net twine which I sealed with
West Systems epoxy.
Taking some flat grained ash and bending three 1/8 pieces 3O
wide over the designed frame produced more comfort and eased the
entry problem. This new beam was lashed in place and the cockpit
rim lashed to it. The second deck beam forward of the cockpit
created a foot brace, however, my son required a shorter brace
than me. I solved this problem by lashing a piece to each
gunwale. Starboard side has three holes in it, port side then
holes with an angled entry to the hole. The fabric will stretch
enough to allow movement of the cross brace but hold it in place
while it is in use.
The frame is a composite of things with Douglas fir keels as deck
stringers and gunwales which have been clad in fiberglass top and
bottom as I did in the three-hole boat. The remaining stringers
are aluminum tubing. The rib and bow and stern pieces are of 3/8
plywood. I covered it with the 15 oz. cloth and used the Gates
N-29 cold bonding compound which I sent you the literature on
I put about 30 lbs in the keel area (fastened securely) and this
makes a world of difference
My final and best design of single kayak was 18 ft. long, 18.5
inches wide overall. My best double was 25ft. long and 19 in.
wide; it was so fast that paddles of usual length Ocould hardly
keep upO, and so I built, for this kayak, somewhat longer
paddles. I would not be surprised if this was the fastest kayak
ever built.
Key design features
My best invention was a Ohip-centering deviceO =A5=A5 a pair of
springy flexible strips (near vertical) that embraced the hips so
that if the boat tipped a few degrees, the hips never moved
laterally. The boat fitted the hips as a skierOs boots fit his
feet. Any play is disastrous. Without such device, a 23-in.-wide
23-ft-long single kayak (OphotonO) was hopelessly tippy. Later,
with the device, it was rock-steady, permitting me to build later
kayaks much narrower yet. An added bonus is that, with the boat
and hips one rigid unit, one has better foundation for vigorous
paddling.
I used a very low gunwale =A5 low freeboard,. A 4-inch wave could
wash into the cockpit =A5 if there were no lap robe.
Of extreme benefit was the combined effect of gunwales close
together (18.5 in.) and low: one could paddle with arms relaxed
=A5 elbows close at the sides, hanging passively, only a few
inches above the water. [In some conventional kayaks, one has to
keep the elbows raised (so that the paddle will not scrape the
gunwales), and oneOs shoulder and upper-arm muscles may become
very tired in 15 minutes. In my kayak, when I paddled non-stop
from Ipswich MA around Cape Ann and back to Ipswich (45 mi.) in 9
hours, I never tired appreciably, even though I am of a skinny
not-very-athletic build.]
The tip of the bow was only about 4 in. above the water. Thus
there was almost no weather-vane effect. A cross-wind was of
little consequence.
I made the backrest do double duty: it served also as the main
transverse strength member.
I used knot-free spruce stringers, canvas, Oairplane dopeO for
waterproofing and tautening, copper and brass hardware, and
well-fitted diagonal braces for rigidity (hard to achieve in a
very slender, very long boat!)
The lowest portion of the seat was made as low and thin as
possible. The flesh of my rear end was only 1/8 inch above the
keelson, only 1/2 in. from the canvas to right and left of the
keelson. Keeping my center of gravity as low as possible was, of
course, essential to achieving stability in such a narrow boat.
The keel at boat center was about 1.5 in. lower than at locations
6 or 8 feet or so forward or rearward of boat center.
To improve stability (increase width at the waterline without
increasing width at gunwales) I adopted use of Osemi-chinesO.
These kayaks seemed ideal in calm water, but were excellent in
big waves also. I often played about in 3 to 6 ft. breakers. I
easily remained upright even when parallel to a 6-ft.-breaker =A5
the boat was so narrow that the wave could exert almost no torque
on it. Paddling perpendicular to a breaker, the kayak would
partially knife through it, rather than ride over it. Knifing
through seemed entirely successful =A5 no sudden upward, or upward
and sidewise, tossing of the bow. On one occasion, in big waves
off the New Jersey coast, I turned end-over-end while planing
(coasting) beachward on a breaker that was about 7 ft. high (the
bow plunged, struck bottom; stern tossed up and over).
A problem I never solved was how to clean out and dry the kayak
interior, after sand (from turbulent surf leaking into the
cockpit) had filtered in. I had no truly tight lap robe.
My kayaks were very light, easy to carry. But they were so long
at the waterline that turning a sharp corner was difficult. Also,
being slender and low, they could carry practically n OfreightO.
Possibly a few of the design features mentioned above would have
some bearing on designs by the Aleuts
Early interest in this shows that they had flexible hinges in
articulated frameworks. Hinges were made from bone. There were
more than 100 such bones in such a framework
I used willow twigs for the ribs which I peeled just before use.
This way they were pliable enough to bend without steaming. I
used my teeth as a vice to facilitate the bending. Once or twice
I heard some creaking which may have been the wood or my teeth
Rolling the Lowie Museum boat at first seemed awkward until I
found that the relatively high deck and large cockpit allows me
to slide forward in the boat with the coaming almost up to my
armpits. This lowers the center of gravity considerable and makes
rolling a simple matter. The Qajaq video from the Alaska state
museum shows some old footage of an Eskimo rolling a King Island
style kayak. He uses the same technique of lowering himself into
the hull of the boat before doing the roll. An Eskimo style
paddling jacket is helpful since a conventional neoprene spray
skirt does not give you as much freedom to slide forward in the
boat.
It is made of Sitka Spruce (willow shoot ribs) with lashing on
all joints
Based on your information that the better Aleut boats used red
cedar, I also used red cedar. The result is a very light weight
boat. It looks like the frame will come in under twenty pounds.
I have carved a Greenland style paddle and have used it with my
Sea Otter (from Pacific Water Sports). I am growing quite fond of
this paddle. It seems to have so many advantages over the spoon
bladed feathered paddles sold in kayak stores that itOs hard to
imagine why anyone uses them. This paddle is better for sculling,
bracing, as a rudder or skeg as well as doing rolls. This being
December and ice starting to form on the shore of Lake Michigan I
have found two more instances of this paddleOs superiority: I
can use it to test the shore ice to see if itOs safe to walk out
on, (it wasnOt) and coming back in in a low surf, I was able to
use the paddle as a pole to shove myself back up on the shore Ice
for a landing.
Ribs
So far, the most time consuming part of building the boat has
been the shaping of the ribs. I would guess that for every two
ribs that I used, I had to throw one away. My success rate is
improving, however, and I would like to pass that knowledge
along.
The first realization was that the bending of wood gets
geometrically harder with the thickness of the wood. Wood does
not stretch , so bending involves compressing the wood on the
inside of the bend. The width of a rib has very little effect on
your ability to bend it i.e. you can make a rib half again as
wide without making it much harder to bend, however, if you made
it half again as thick, youOd notice quite a difference.
Compressibility of the wood improves if you heat it. Water also
helps. With unpressurized steam, you are limited to 100 degrees
C.
I used white as well as black ash for the ribs. I got best
results with bending if I kept the thickness between 1/4 and 3/8
of an inch. Straightness of grain gets more critical as the bends
get tighter. On tight bends, the wood tends to separate at places
where the grain comes out of the surface of the rib.
Irregularities in the grain are not as critical in the straight
part of a rib.
Uniform or at least controlled variation in thickness is
important to the shape of the rib. If you bend a rib freehand, it
will tend to bend the most at the thinnest part. Hence,
variations in thickness will work against a smooth curve. If you
use a form for bending and can keep the rib clamped to the form
until the bend sets, then thickness is not quite so much of an
issue.
I have not tried to bend any woods other than ash. Softer woods
such as pine or spruce might be easier to bend
I have read in some woodworking magazines that chemicals can also
be used to weaken the bonds that hold wood fibers together and
thus make bending easier. I have not tried any of these yet, so I
canOt vouch for their efficacy, but I pass them along anyway.
Number one method =A5 traditional northwest Pacific coast Indians
used stale urine to soak the wood. Breakdown of urine apparently
produces some chemicals, most likely urea which softens the wood.
Number two method =A5 One part Downey fabric softener to eight
parts water. Heat the mixture to boiling and soak the wood in it
for about an hour. This seems more appealing than the stale
urine..
I have finished my Greenland kayak and am now starting on a
replica of the Lowie Museum one holer. I am again doing it in
wood with western red cedar for the longitudinal members, pine
and spruce for the deck beams and ash for the ribs. The weight of
the frame should come out pretty close to that of the original,
namely 26 pounds or so. I am making it slightly longer to take
advatage of the full length of the 16 feet that the lumber comes
in. I am also making it about 1.5 inches wider in the middle. I
hope this does not do too much violence to the original
hydrodynamics.
I suspect that as I add ribs and stringers, the movement of the
deck will become restricted. However, since the stem and stern
boards which connect the gunwales come in two pieces and are
hinged, some independent up and down motion of the gunwales will
still be possible. The drawings of the Lowie Museum boat do show
dowels connecting the gunwales just short of the stem and stern.
I suppose we can think of them as minor deck beams. However,
their thinness suggests that the boatOs builder wanted to
restrict motion, but not eliminate it altogether.
This construction contrasts with that of the Greenland boat which
has the gunwales pegged and lashed at the stem and stern to
maximize stiffness.
The Greenland boat is rather more difficult to handle than I
expected. The first time out on Lake Michigan with 3 foot waves I
took a swim. I have since added some padding around the hip and
thigh area which helps with bracing. IOve had it out a few times
since the original swim and am getting more comfortable in it.
Like the Aleut kayaks, the Greenland kayak has a V bottom. In
practicing reentry and roll in a pool, I got quite a bit of water
in it. The boat stayed surprisingly stable unlike my flat
bottomed commercial fiberglass boat which turns treacherous when
swamped. The V seems to keep the water confined to the bilge. In
addition, the stringers and ribs probable act as baffles to keep
the water from shifting around and relocating the center of
gravity. In the flat bottomed boat a slight lean to the left or
right will send all the water rushing to the side of the lean
with disastrous effects.
I have also experimented with willow twigs as rib material. A
four year old willow shoot when stripped of its bark has a
diameter somewhere between 3/8 and 1/2 inch which is the diameter
shown for many of the baidarka ribs. I was able to cold bend the
willow branch into the desired shape right after peeling. The
tighter bends can be achieved by judicious crushing of the wood
fiber with oneOs teeth. This process seems to be preferable to
steam bending because it allows better on the spot control of the
shape of the ribs. If a rib has the wrong shape, you do not need
to reheat it to reshape it. Also, in steaming ribs, you typically
have to clamp them to some sort of form until they take a seat.
After a week I called the factory and talked to the
engineer/chemist about this. He said this was not unusual, since
the hypalon cures by a combination of solvent evaporation,
moisture, and UV exposure.
it gave me a chance to try out another Gates product recommended
by their chemist, which is an activator to mix with the hypalon
to give it a quicker cure and better ozone and chemical
resistance. I did notice some difference in this final coat,
though he admitted that the difference in cure time was not
radical, reducing it by only 30% or so, which is still about 3-4
weeks wait. From this limited experience I feel that the
activator is probably worth the slight additional expense and
trouble.
The best part of all this was the discovery of the N-29 neoprene
system. It is an excellent adhesive to itself and to other
materials, if properly prepared, acting like a contact cement
specific for neoprene. Additionally the chemist highly
recommended it alone as a higher performance material than the
hypalon/ neoprene system. And while the stuff generally comes in
a basic black, it is available on special order in its natural
state which is a clear amber or honey color. It will turn darker
under sunlight, since itOs color stability is not as great as
hypalon, but it could be topcoated and the bleed through problem
should not be so bad in clear N-29 and possibly a color other
than white in the topcoat. If it was left uncoated it would
probably give the translucent skin you have mentioned before. I
have enclosed product data sheets on all these products. Check
particularly the performance data of the N-29 in elongation,
resilience, water resistance, and abrasion resistance
Recently I was fortunate enough to paddle a wooden framed kayak
patterned after the OUnalaskaO boat surveyed by Howard Chapelle
in 1949. It was built by Jim Dwyer who was in the Coast Guard in
Kodiak when he built it. The frame was covered with what appears
to be a thin fiberglass like material. I am writing to Jim now to
find out just what was used. I suspect that it was covered with
ceconite aircraft fabric and coated with a clear epoxy resin (see
Wooden Boat Vol. 58 pgs 69-73). In any case the resulting skin is
slightly flexible and looks like the translucent seal skin
described by early explorers. I highly recommend this combination
to builders of authentic looking baidarkas. When I was paddling
this beautiful baidarka across StephanOs Passage in 3 to 4 foot
white caps and short breaking waves, the OUnalaskaO baidarka did
flex and bend slightly with the waves. I would only recommend
this design to those who feel confident of their roll or who
donOt mind swimming ( I was forced to do a couple of unplanned
rolls.) It is sleek and fast for its length and handles more
comfortably loaded than empty. On the other had it tracks better
than any other rudderless kayak I have ever paddled. It even
tracked well in quartering waves and wind.