RE: Vent
Assuming you mean the stbd water tank under the sette. It is vented through the stanchion that is just behind the water fill cap on the stbd side. You should see 2 small holes just above the base on the outboard side. Use a toothpick, piece of wire or an awl to make sure the holes are open. If you stick a fast running hose down the fill tube, you should be able for force water out of the vent. Wasps, mud daubers or something have probably built a nest. If you can't force them out through the vent, disconnect the vent line at the tank, aim toward the bilge before you try to backwash the vent line. You don't want the critters in your water tank. The vent arangement is the same on the port side for the holding tank.