My dad built a 10' car top boat out of plywood about 50 years ago. He used the Weldwood glue mixed from powder (can't remember the exact name) with little brass ring shanked nails. We used that boat for everything from fishing in the salt chuck to water skiing on the lakes (only when I was a young, light kid!) and none of the joints were fiberglassed. Looking back, it was amazing what we put it through, maybe not quite like falling out of the back of a pickup, but it still stood up very well with only glued joints.
