Here's a closeup. I don't have a clue on this. The spot is approx. 1 inch in diameter and is below being flush with the Gelcoat surface approx. .025" and appears to be hard as a rock when probed. The brass keel guard is not compromised or damaged and appears to be bedded in 5200. I'm at a loss on
this one! The boat has been to Lake powell once and Bellingham and the San Juans twice, so it's not like it's been in the water constantly. HELP!