Lew Crenshaw: ... The frame, when complete, will resemble a traditional
Greenland style frame. The gunwales will look like an I-beam with the plwood
serving as the core and yellow cedar strips at the corners (except for the
top inside edge which will have a beefier strip of ash to support the deck
beams).
Ralph Hoehn: This is a fresh and exciting approach, Lew.
FYI: Pouch uses a wide "plank" for the gunwales on the E68 single. They
router a groove in both faces to reduce weight, creating a sort of I-Beam.
Since speed of production is of no concern to an amateur builder, i prefer
the laminated solution for its potential in further weight savings and
smaller risk of breakage (plywood and laminated lumber tends not to split
very easily and if it does, the split stops at the next lamination).
Hope you don't mind more detail questions coming up: How will you be securing
the deckbeams to the gunwales?
LC: The frame will be assembled in two halves (each half
consisting of six gunwale segments).
RH: How are you joining the gunwale sections? How will they be secured
against separating?
LC: Once the gunwales are assembled and the deck beams installed, the ribs
(steamed y. cedar or ash) will be inserted into mortised areas of the
gunwales, followed by the installation of the two chines and the keelson.
RH: Again, how are you going to hold the frame members together at this stage?
LC: The two halves will be inserted into the skin and longitudinal tension
will be placed on the frame ...
RH: You're killing me: How? Are you stepping / interlocking the keelson
sections at the mid point (presumably in the area of the cockpit) and then
forcing them down into the hull?
LC: ... so that the last two gunwales pieces may be installed.
RH: Sprung into place? Will that be possible with all the deck beams and ribs
already installed? Most folding kayak designers leave out the "masik" and the
"backrest" frames until the keelson, stringers and gunwales are sprung into
place, then insert them horizontally and twist them upright, thereby
achieving final vertical and lateral tension.
"Traditional wisdom" has it that skins stretch over time and are not
sufficient to hold the frame together in such a way that it remains stiff.
That may not be a concern any more if you use low/no-stretch fabric
(polyester, "Cordura"). What are you intending to use for skin material? What
will you use for coating? or are you looking to build the skin out of
pre-coated material?
LC: From there, if lateral tension is required, I'll install low volume
sponsons.
RH: Do you have a source for those yet?
LC: I like the idea Pouch uses on it stern seam. I think I'll try to pursue
that idea instead of the zipper.
RH: I have yet to try out a variation on that theme:
1 - Take two aluminium tubes, one large enough for the other to fit inside of
it and slit down one side.
2 - Insert them into sleeves sewn to the deck edges, so that the smaller is
within its own sleeve, but also wrapped in the other sleeve within the other
tube.
Is that a clear picture? What do you think?
Best regards,
Ralph
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