Been battling this problem for several years in my CD22. If the boat sat in water and collected rain in cockpit the cabin filled with up to 2" of water. I knew the seam at base of cabin bulkead was cracked and figured it was the cause. I tried heavy 5200 along seam to little avail. This spring I had the entire seam reglassed professionally including sealing off the drain hole. Today I launched the boat for first time and had to take it back out to address an unrelated issue. In the brief moments it was in the water, I managed to collect a cup of rusty colored water at the step to the berth area. I am totally mystified where this water can possibly be coming from. Is it possible to have water in the hull that is seeping out somewhere? I don't know where to go from here.