I have a 232 Gulfstream; yesterday I was cleaning up the boat and found a through-hull drain I can't identify. It is the forward most through-hull about 8" or so above the water line on the port side. Whatever it is, it may be blocked. I tried to clear it from the outside with water pressure but the water didn't drain so I don't know where it went or how to clear it from inside. Anybody got a clue?