Did you drop pots on the mainland side of the bay or the ocean side? Last time that we went we had heard that the ocean side of the bay was the place to crab, after we had crabbed on the mainland side for 3 hours and got 1 keeper!
We were directly across from the entrance to the East marina, just down from the daymark there. There were quite a few pots upriver of there. I don't bother with halfmoon bay, too many lines to avoid for my boat.