I have heard that the exhaust tube isn't secured very well in the transom. That area is cored, so if water gets in there, it's got access to the balsa core in the transom and the hull, and can cause the type of problem you're describing. The hull was built in two halves and glassed together down the center, so a wet stbd side is consistent with a leaky exhaust.
I've seen other people talk about the same problem in this forum.
Good luck!
