JB,You don;t say if the leak shows up low or high, but I'm going to presume low. Several possibilities that I can think of.On our 356 we had a leak that was coming in at the seam between the hull and transom scoop at the seam. When motoring, the boat squats a bit and this area is underwater. When sailing, it is above water. A little patch work and all is now dry.Another possibility is you are ggetting water from the stuffing box or the exhaust. Others may have some additional ideas. I thought my seam leak was from an overactive stuffing box for quite awhile.Dan Jonas (S/V Feije II)