There may be a pinhole on the inside letting water at the plywood, but without seeing the spot, it's hard to know. It would be unusual for a pin hole to show discoloration so fast. Any way you can post a picture?

: I just finished building a Mill Creek 15 and launched her yesterday. I took
: her out for a few minutes today then brought her back in. When checking
: over her an hour or so later, I noticed a discoloration radiating from the
: stem in the stern (where the side panels are joined together). It's
: slightly larger than a quarter on one side and twice that size on the
: other. It's grayish, like a bruise. I put two layers of fiberglass in that
: area, epoxied well, and it has 9 coats of Epifanes wood gloss/varnish on
: top of that. Any ideas?

: Thanks,
: Jenny