Subject: Re: [baidarka] alternative ribs
From: Robert August (robertaugust@hotmail.com)
Date: Fri Apr 13 2001 - 11:10:48 EDT
To me it doesn't sound crazy...just a lot of work. In thinking of how I
would go about such a task the best idea I have is to make a "plug" of how
the boat would be and then mold the ribs from that as just about no two ribs
are the same. like traditional boatbuilding you end up building the boat
twice. With traditional woodboat building one builds a strongback, erects
molds for the shape of the boat, connects the molds with longitudinal
ribbands (at this point the shape of the boat is visible but almost none of
the wood you see will end up in the finished product)the keel,stem and
transom are fitted, the boat planked, and frames (ribs) are fitted (steam
bent or sawn) and the hull is done. There are many variations on this
sequence. If I were going to the trouble of making a plug to mold the ribs
from I would just go ahead and make a wood strip boat sheathed with epoxy
and glass.
To me steam bending is magical and a bit of a gamble. Taking a piece of
oak hot from the steambox (pvc gloves with wool gloves under for
insulation!) and bending it to shape on the structure of the boat where it
will remain is a wonder. Just watch the steam, have tongs to grab the work
from the box, and make sure to have a big enough heat source to make the
steam. The gamble is that not every rib will turn out exactly as intended
(having a jig will help a bunch) and some will break in the process. If you
get a lot of breakage step back and think it through... does the wood need
to soak more? what is the grain like in the pieces that broke? Is there
enough steam?
If ya can think of a way to mold the carbon fiber/ glass / kevlar ribs
without having to build a complicated mold then they would be worth the
effort IMHO.
Rob August
>Has anyone ever heard of fabricating ribs out of kevlar or carbon fibre?
>Frankly the idea of steam bending wood scares me, and since I have quite a
>bit
>of composite expierience, I thought it might be interesting to try and make
>ribs, say with three layers of cloth, two of 1 inch kevlar tape "on the
>inside" and one of carbon fibre on the outside of the rib. does this sound
>crazy?
>
>
>thanks in advance
>
>-
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