Puzzle joints: how to proceed?

Builder's Forum
1

So I glued together the puzzle joints for my Wood Duck, and they turned out not as good as I expected. The fiberglass got wrinkled, and also there are some (not many) white spots, where it was not properly saturated. The joints feel strong to touch, though.

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I am contemplating my options now.

  1. Try to take them apart with a hair dryer, and do it again, nicely.
  2. Sand and proceed with the build
  3. Leave as is, proceed with the build, and sand when I am sanding the entire boat.

I am going to glass the entire boat in and out, following Laszlo’s advice.

Thoughts/suggestions? Thank you!

2

(2). Sand smooth but do not sand through the cloth into the wood. Using 120 grit paper will help you control the progress

3

The only way to get rid of the white areas and wrinkles is to remove the unsaturated cloth. How to remove it, how much of it to remove and what kind of patch job are the options.

Assuming you remove the entire piece of glass tape (either with heat or sandpaper), you can guarantee perfect saturation by wetting out the new tape and then applying it to the joint instead of applying and then wetting it out. Wetting it out off the joint also eliminates the chances of wrinkles forming as a result of working the tape to get a good saturation.

With glass on both sides, the joint won’t need the tape for strength so you can alternatively remove only the unsaturated and wrinkled areas. If you do this, be sure to fill the divots with some kind of filler appropriate to the final finish; unthickened epoxy for a bright finish, epoxy/phenolic microballoons for painted, etc. Unfilled voids are water traps, stress concentrators and starting points for delamination.

Finally, definitely do some sanding the way David suggests before putting glass over the joint. The joint must be smooth enough so that the next layer of glass sits flat and doesn’t snag on anything, otherwise you could end up with bubbles and voids again.

Good luck,

Laszlo

4

OK, thanks, I think I’ll just try sanding them smooth and proceeding with the build.

5

In the future one idea that works well is to clamp the lay up (fiberglass/wood/fiberlass) between two boards that overlap the joint by 3” or so on both side. Protect the boards on both sides with polyethylene. Use 2 clamps on each side of the joint (4 clamps total). There will be lots of epoxy runout but you end up with a very smooth and bubble free joint. Just an idea

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