How to Build a Kevlar Canoe - II

“Fixin' the form and Shrink Wrap"

We used a pre-mixed drywall compound to touch up the damage from the last canoe release.  Although it's been 3 years since the last one, there was no additional damage to the form from the intervening storage in the barn (under a tarp).  The form was then sanded down (gently), in preparation for re-waxing the repaired spots.

The following weekend we put on the shrink wrap.  This was ordered (~$25) on line; it's used to cover large windows for winter ("picture" windows, sliding glass doors, etc.).  6 feet by 25 feet, I think.  The trick appears to be to put it on as tight as you can before heating.  We used double-backed tape on the gunwales and stems.  We also duct-taped up the excess underneath.  Be very careful when shrinking.  I did each side slowly, then came back and got out the wrinkles.  You can smooth/stretch the wrap to the sides, the heat it to shrink, then stretch some more.  This is what it looks like in the "gathers" section near the portage yoke area.  I was able to get almost all of it out.  It does take some patience.   We spent about 2 hours putting the shrink wrap on and shrinking it down.  The end result looks pretty darn good!  I did manage to burn through on one spot (it's real easy), which was repaired with more double backed tape and shrink film.



We also did a test run of the Kevlar-over-shrink wrap to see what it would be like coming off the mold.  This is just a 5 gal pail with double backed tape in a 10"x22" section.  I used some leftover Kevlar (from 3 years ago!) for the test.  It tacked up in about an hour (97F out!) with West 105 and 207 hardener.  It came off the pail just fine - no issues whatsoever.


We also worked on the hotwire rig for cutting the foam strips for the ribs.  We will cut the last 1/2" of a 4x8 sheet of 2" yellow polystyrene as shown below.  The "Trapezoid" is what the book tells you to do.  We think we'll get a cleaner rib this way.

As you can can see, all this does is essentially round the corners on the trapezoid of the original design.  The hotwire cutter will make a nice clean cut, as the hotwire strongback makes an arc of 1-1/4".  More on this later.


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