Never close valve
Dan,The scupper drain valve will never be closed. Leave it open all the time. If you have a drain for the sink, there will be a line that runs into the scupper drain hose. You should have a shut off valve on that line. This should be CLOSED when the sink is not being used. If you valve to the scupper ever became clogged, the water would back up the sink hose and come into the cabin!! I removed this line because we do not use the sink, or the gally. If this is confusing let me know. If you think about it for a moment it is real simple. You will love this boat, it is alot of fun.Dale