Tuesday, October 4, 2016

Canvas - Round Two Completed!

This post originally appeared on Windborne in Puget Sound

Round two of cockpit canvas replacement - the roof section of the dodger - is done!  Here's how it went:

Topstitching the aft tail seam
Having completed the actual construction of the panel, I needed to create the attachment to the "windshield" portion of the dodger. The original canvas had the roof and the windshield sewn together, making a hugely unwieldly thing, almost impossible to handle with all the compound curvature and the easily damaged vinyl.  As I reported last time, I made a design decision:  The new roof panel would be separate, and attach to the windshield via Common Sense fasteners.

So, how to locate those fasteners?  For a taut roof panel, the fasteners need to be in the exact right spot, and further, the eyelets and male portions need to end up in registration with each other.  How to do this?  I solve problems like this as I am falling asleep and letting my subconscious work on them.  This is the procedure I came up with: 
  • Mark, on the tuck back tail of the new roof panel the desired location for fasteners - this portion will show in the final installation
  • Place the new roof panel in place, carefully aligning the sides, and positioning the front seam on the front surface of the tube, as designed.  You'll note that the old panel seam (built by a professional) missed the tube by as much as an inch in the center.
  • Insert T-pins at the marked locations.  By pushing them all the way in, they made a good solid temporary connection because the vinyl in the windshield gripped them, allowing tension to be applied so that wrinkles could be worked out.  Adjust the T-pin locations in the windshield as required (keep the pin locations in the tail as marked since, again, these will show) and reposition as needed for a good fit everywhere.
  • Mark exactly the T-pin locations on both the tuck back tail, and the windshield.  To mark the windshield, pull a pin part way out, giving enough room to work under the tail, but keeping the location established.  Since this is all done with the existing canvas all in place, it is easy because the old roof panel is keeping the windshield tensioned and in place.

T-pins for alignment
  • Pull the new canvas off
  • Punch holes in the windshield using Sailrite's Common Sense punch...  this is the only way to do this, given that 4 layers of Sunbrella and the vinyl need to be cut.  Jane was inside, with a buck made out of a 6" piece of railroad track with a piece of Starboard taped on as the working surface.  Without something to work against, the punch would not have worked.
  • Install the eyelets in the windshield.
Holes punched and eyelets installed
  • Install the male portions of the fasteners on the tuck back tail of the new canvas.  Getting the male fastener mounting holes in the right place cannot be done by eyeball.  I made myself a jig out of an old blank non-silvered CD, by drilling holes at the correct spacing and then marking the outline of the fastener and horizontal and vertical centerlines.  This can then be held in place on the marked T-pin location and a pen can be used to mark the rivet locations thru the holes in the jig.  (Sailrite?  Are you listening?  You need to sell something like this...)
Homemade drilling jig
  • The moment of truth: Test fit.  Will everything work?  In order to get a true assessment, I disconnected the rear of the old canvas from the rear tube and installed the new canvas completely.  Since the old roof canvas was still attached to the windshield, it hung down inside.  Yup, it looked good.
Test fitting
OK, punching the holes in the windshield was a commitment, but not a serious one...  Eventually tho, it was time to make the big jump, and say "I do."  So I cut the old roof panel off of the windshield and voilà, c'est fini!

And man oh man is it good to see the old faded canvas as a jumbled up pile (and eventually in the dumpster) instead of gracing the cockpit!

Good riddance!

Now there is only one more roof panel to make - the center section.  This is much simpler to construct, being a single panel of cloth with only edging installed.  Ah, but exact sizing and zipper placement are critical for a taut installation.  Gotta think about this...

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