Mine is wet below the waterline from about 2' behind the bow all the way back, and halfway up the transom on the starboard side.
I think the primary source of water intrusion is the engine exhaust, which seems to be an issue with many of the J 30's (there are numerous discusion n this issue on this web site), but I am also planing on having the rudder fittings rebeded along with all of the boats thru hulls just to be safe.
It doesn't sound like your boat has the sme problem though, I would suggest checking the anchor locker and drain, the starboard chain plate & bulkhead, deck fittings and around the keel.
