Sounds like it might be a case of the "black ick" which is caused by moisture migrating from the inside toward the outside fiberglass, accompanied by mold growth. So tell us a bit more. How was the interior sealed (how many coats of resin and or glass)? Do you air out the compartments after use? Is the boat stored outside with the hatches on so that condensation can build up? Where on the boat are the black areas located.

Ted

: My boat's a couple of years old, and in the last year it's grown what appears
: to be mold in a couple of spots. It's black lines that I can actually feel
: under the epoxy. Any suggestions on what to do? I'd hate to sand right
: thru the top layer of okume.

: Thanks,
: jim