Subject: Re: [baidarka] Ochoa's Glacier Baidarka
From: Juan Ochoa (jochoa@ll.mit.edu)
Date: Fri Jul 25 2003 - 15:40:54 EDT
John Hess wrote:
Is it designed after any particular historical or contemporary model?
It is modeled after Bill Low's personal baidarka which has its origins
with the Lowe Museum specimen
What are its important dimensions?
The LOA is 18'. The beam is 20". I don't recall off-hand what the DTS
is.
The keel appears to be a different depth in "Completed Bow" vs. "Bow
Detail"? You also have a "Keel Lamination" shot. Did you build up the
depth of the keel while it was attached to the frame?
The keel is made up of three laminations. I temporarily set the first
lamination with supports, as can be seen in the "Temp. keel support"
photo. Both the bow and stern fins were shaped to smoothly match the
curve of this lamination. Once all the ribs were in place and properly
fitted, I glued and clamped the remaining keel laminations, see "Keel
lamination"
In the photo "Finished Keel" there appears to be a slot at the near end.
What is its purpose?
Well, it wasn't totally finished in that shot. I still needed to plane
the sides smooth and add rounded edges. The slot is an artifact that the
three strips were of different lengths. When I attached the laminated
keel to the bow and stern fins, I cut it to length and faired it to the
proper shape.
What type(s) of wood did you use?
The kayak is plain ol' white pine except for ash ribs, coaming, and
alternate laminations in the deck beams.
Did you laminate or steam bend the ribs?
Both actually. I steam bent the laminations to the forms and let them
cool/dry in place. I had very little spring-back and very consistent
shapes.
What type of glue did you use in your laminations?
Ribs and coaming, Gorilla Glue. All the rest was TiteBond II.
Did you use CAD to design the molds, etc.?
I did make a 2D CAD drawing of the whole kayak before cutting very much
wood. That was actually very helpful as you get to study the shape and
make plenty of mistakes at essentially a zero cost. The other benefit is
that when you get to building in wood, there few surprises.
I created the shape of 5-6 ribs more or less by seat-of-the-pants design:
I knew what I wanted that part of the hull to do. The rest of the ribs,
I shaped by interpolation using the solid modeling of the CAD program.
It sort of worked. Out of the 16 ribs, 3 were just the wrong beam and
another was the wrong shape. Eyeball and freehand shaping of the forms
fixed that.
In the end, there are only 2 ribs with spacer blocks (1/8" to 1/4" thick)
between them and the stringers. The overall shape "seems" like it should
be fair. At least, it is symmetric. I spent a fair amount of effort
making sure that the boat was true. It is symmetric to less than 2mm
over the 18' length. (Yes, I know, but physicists love symmetry).
Good luck with your skinning.
It is in process. I'm using the 13 oz poly and I don't see what all the
fuss is about. It is no trouble to work with.
I'm looking forward to your on-the-water report.
OK, but don't hold your breath.
______________________________________
Juan Ochoa
Quantum Electronics Group
MIT Lincoln Laboratory
jochoa@ll.mit.edu
(781) 981-0657
(781) 981-0602 FAX
-
Baidarka Mailing List - All postings copyright the author and not to be
reproduced outside Baidarka or Baidarka archives without author's permission
Submissions: baidarka@paddlewise.net
Subscriptions: baidarka-request@paddlewise.net
Searchable archive: http://rtpnet.org/robroy/baidarka
This archive was generated by hypermail 2b27 : Fri Aug 01 2003 - 01:30:04 EDT