How to Build a Kevlar Canoe - II

“Sealing ends, gunwale work"

Here's one way to make sure your ends are straight.  I pivoted the square shown here to make a mark on both sides.  I could then 1) determine a reference point perpendicular to the keel line and 2) use those reference points to get each side of the bow and stern straight.  Once I got that, I used a quick-bar clamp to open up the end so I could lay in the kevlar and glass to seal the ends.  I used a piece of cardboard (as shown) to keep the end open while the epoxy cured. 


Once this sets up, I can work on the outside.  Here, the outside has already been sealed, but there were a few hollow spots, so I laid in some s-glass as a filler.


Now for the fun part.  The gunwales have been scarfed together using colloidal silica, epoxy and about a 4" joint.  We then ran them through the planer for consistency.  We're making 3 canoes, so it was all done in one setting.  Now I can put the inwales in, trimming them as shown.

Next day, we installed the inwales and outwales.  I chose to use 3/4" brass screws.  The inwales are slightly less than 3/8", and the outwales are slightly less than 1/2".  Keep in mind this is cherry, so we expect to get by with less width than a lighter wood like Luan mahogany.  I measured from the keel line to the gunwale on both sides to assure I had the same freeboard each side. 

I then clamped them in place, drilled a pilot hole the same size as the screw un-threaded region, but only through the inwale.  I then used a much smaller bit as a pilot through the Kevlar and partway into the outwale.  I counter sunk each hole and installed a screw in each hole.  Note that before I tightened each screw, a clamp was installed on each side of it to assure good penetration.

I then trimmed off the excess Kevlar with a fine toothed coping saw.  I did experiment with a box cutter; it will work, but it dulls the blade very fast.  I had to put in a new blade for each quarter.  The gunwales were then sanded with a random orbital sander (or belt sander, for the ends).  Here's what it looks like at the end of the day.

We also planed the gunwales prior to installation, along with the material for the seats, thwarts and yokes.  Tomorrow we hope to finish with the gunwales and install the ribs.

Next day - Tom is drilling (and countersinking) the gunwales for screws.  He used 3/4" #8 stainless (from the inside out), while I used 3/4" #6 brass. Since the inwales are a little less than 3/8", that gives us about a 3/8" "bite" into the 1/2" outwale.  I weighed my canoe - 30 lbs with gunwales installed, but still needs seats, ribs, thwarts, portage yoke and a finish coat applied.  I'm still hoping for 40 lbs.

Note that Jim says to apply the finish coat before the gunwales are installed.  We didn't do that last time, and won't again this time.  It's too hard to turn the canoe upside down without the gunwales on.



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