There is a drain in the stern end of the basin. I just replaced the mast step on my boat. Previous owner had drill 4 holes in anchor locker because that drain was plugged. While the mast step was being mad e I drilled out the opening to make it larger, but I still have water in the basin , 1/4 inch, a fair amount of time I believe the problem I have is that it is level or slightly off . My water is coming from the anchor well which is on the project list.