Thanks JJ, maybe I can explain it a bit better...
The self-bailing deck has one drain (maybe 1-1/2" dia) that empties into a lower well just forward of the transom. This well is always wet when anchored or drifting and dry when underway. If weight (people/fish) is added aft while the boat is stationary, water flows back to the deck. It can get a few inches deep.
Thanks,
O
found this:
http://www.yachtsurvey.com/boatreviews/GradyOS24-5.JPGsimilar in that the drain is on the deck (left) and it outlets just forward of the transom (second tier to right). I hope this makes sense.