| Construction |
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Ripping Stringers, Gunwales and Keelson We
were barely able to get all of those pieces from our 2X8. But its clarity
meant we will probably only need to scarf one joint (maybe three) in all
of the spruce pieces. Any other board we saw probably would have meant
the need for 20 or 30 scarf joints. We have yet to make a perfect scarf
joint and scarfing takes time. While our scarf joints work ok, we give
them about a 7 out of 10 for "pretty". So we like to avoid them when we
can. If we hadn't been so lucky, we would have been wise to look at longer
and wider boards. "Clearer" seems to go hand-in-hand with "longer" and
"wider".
Platt Monfort (designer of the SnowShoe 14) recommended a Piranha saw blade because it takes a narrow kerf and leaves little finishing to do. We used one and we agree. Had we used a thicker blade, our significant sawdust pile would have been twice as significant and we would have needed more raw material. One of us tends to overkill with thinking. Looking back, a couple more bucks spent on lumber would have saved a pile of thinking. (Our 16 foot spruce 2x8 only cost $16.) |
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 We
got 18.5# of finished stringers, keelson and gunnels from a 46# spruce
2 X 8 that was sixteen feet long. The moisture content tested at 19%
The canoe drawings show how to get the stringers, keelson, inwales, outwales,
and rub rails all from one 15 foot 1" X 6" board. We felt fortunate in
finding a 16 foot spruce 2X8 that had just one significant knot. It was
the best by far among 100 of its 'brethern'.
Although it was still pretty green, there was already some checking down the center. So, we elected to rip out our pieces before the plank had an opportunity to dry and check further. It is difficult for us to feed long stock through a table saw with precision. Furthermore, internal stresses relieved during ripping often cause the boards to emerge from the saw blade with a pronounced curvature. That curvature tends to force the board away from the fence. It also makes the next cuts on the same boards more problematic. So, we elected to cut all of our dimensions nominally 1/16 inch "fat". We could have hand-planed them to size in a few hours, but Lee's industrial power planer sped the work for us. |
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Feather Board Feather
boards afforded us better control over the ripping process and improved
our cutting accuracy.
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Preforming Gunwales The
gunwales follow a three dimensional curve in the canoe. When you try to
bend them into place on the forms, their "sky" edges will naturally tend
to twist outwardly amidships. If the outward twist is far enough, then
the heat-shrink dacron covering may have a tendency to peel off the outwale.
(The adhesive that will be used to glue it to the outwales can withstand
shearing forces well, but it cannot withstand peeling forces nearly as
well.)
By preforming them into a two-dimensional arc, we expected to diminish the tendency for the gunwales to twist when set in their final curves on the forms. We submerged all four pieces in water for 24 hours. Then we clamped the four together side-by-side, bridged them across end supports and applied weights to bow the center down until it touched the ground. We kept them moist for another 24 hours. Then we let the wood had dry for another couple of days When we removed the clamps and weights, we found that the pieces were nicely curved. [ED. NOTE: As you will see later, the curve that we got was not sufficient to overcome the tendency of the parts to twist as much as what we felt was required. Perhaps we should have substantially increased the depth of the bow after the first day and kept the pieces moistened and weighted for an additional day or two.] |
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Outwales Outwales
installed on the station molds.
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 Although
our outwales were pre-bent, they will not fit flatly into the station mold
slots.
This angle could make it difficult to keep the fabric from peeling off the outwales. So we'd prefer that the outwale twist followed the mold cut-outs more faithfully than this. |
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 The
wooden wrench shows the angle assumed by the unrestrained outwale.
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 Torquing
the outwale between the middle stations also brings them into better alignment
at the stems. We'll try to fix this later.
[ED. NOTE: We did fix this later. Our solution commenced with the making of a bunch of those wooden wrenches that we would use for twisting the gunwale into its proper alignment. Then we removed each outwale, soaked it in saturated steam. After soaking fifteen minutes, we quickly clamped the outwale back on the canoe forms, and we applied wooden wrenchs to them at key points where we needed to change the twist of the outwale. Next, we each grabbed two of the wrench handles and applied enough torque to twist the outwale into proper form (plus a bit more to allow for springback). (All of this had to be done fast since the steamed wood begins losing its plasticity the moment you take it out of the steam.) We held them there a few minutes to give the core of the outwale time to cool a bit more. Then we restrained the wrenches in those positions with heavy twin. We also added a few more wrenches where and as we thought would do some good. We left the outwale constrained like that for a full day. We learned the hard way that the outwale would not hold shape if we didn't restrain the wood for at least twenty-four hours. We think that the holding time gives the wood time to lose much of the moisture that it picked up during steaming -- the wood tends to remain more plastic until it does that.] Before continuing with construction, we repeated this procedure for the other outwale and for both inwales. Before going to this approach, we first tried the same technique that had worked to remove the warp from our keelson (i.e., wet paper towels, a hot iron, and reshaping finesse). It didn't work here. Steam twisting appears to be more difficult than steam bending.] |
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Warped Keelson Shortly
after ripping the the keelson out of our 2X8, we discovered that it had
developed this pronounced warp!
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 We
straightened it with a gerry-rigged fixture, sopping-wet paper towels,
a hot iron, finesse, and patience.
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 Notice
how much over-bending we applied in straightening the bow.
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 Success!
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Stem, Knee, Keelson Stem,
knee and keelson joined and shaped.
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Keelson Reshaping Our
free-hand shaping of the keelson-to-stem transitions seemed too abrupt
and looked pretty amateurish. So, we decided to re-taper them in smooth
curves beginning tangent at the end station molds and running to the stems.
We also decided that we should have used guide lines for the cutting.
Here is how we established the new cutting lines: We set a straight and narrow batten onto the keelson such that its straightest edge was inline with the original keelson edge. We clamped it just inboard of the end station mold so that it could not move at the Station mold when the batten end was flexed laterally. Then we flexed the outboard end of the batton toward the canoe centerline just far enough that the curve of the batten's "straight" edge passed over the point on the stem where we wanted our faired keelson curve to terminate. Holding it there, we scribed that curve onto the keelson. We repeated this for each of the two curves at each end. To assure symmetry we took care that the batton was always well-clamped at its tangency point and that we always applied the bending force to the batten at the same distance from that point. |
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 After
we had re-cut the keelson to the lines that we had scribed between the
last station molds and the stems with a block plane, they looked like this.
That's better!
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