The next step is to form the air duct on the underside of the lid. I used 1/2 inch foam for
this but I think I would have gotten a little more air flow if I had used 3/4 inch foam which would have given me a less restictive
duct. Mine works well but I may decide to make a new duct later. The choice is yours.
Cut a pieice of foam just large enough
to cover the hole in the bottom of the lid. Cover the underside of the lid rim with duct tape and lightly tack the peice
of foam to the bottom of the lid. Be sure the lid will still close properly with this in place.
Cover the foam with duct tape and place a layer of glass cloth over it and then coat the cloth with resin. You can ,
if you choose, leave the duct tape off the foam and dissolve the foam later with acetone. Be sure to make the cloth
larger than the foam in order to form a flange to use to fasten it down later. Once the fiberglass is dry and hard remove
it from the lid and trim off the excess leaving a flange to mount it with. Remove the foam from inside it and you will
be left with a thin fiberglass air duct. Sand all rough or sharp spots and edges smooth. Drill a 1/4 or 3/8 hole in
the corner of the duct under the coil to allow condensation to drain into the cooler
Mount the bilge pump in the
corner of the bottom keeping it about 1/2 inch off both sides to allow good water flow all around it. Screw it down with
some sealer on the screws to prevent leaks. You could also glue it down if you choose. Point the outlet of
the pump parrallel with the side or back wall of the cooler.
Place a bead of silicone
around the bottom air duct and attach it to the underside of the lid. Self drilling stainless screws work
well but pop rivets would work as well. I want to be able to take it apart for refinement, but the choice is yours.
Don't drill a hole in the coil. Cut a hole in the duct for the hoses to pass through into the cooler.Attach
the hoses to the coil with one end of a hose attached to the pump. leave a little slack in this hose for the lid to
operate freely. The other hose just dumps the water back into the cooler and lays on the bottom. I have
added a 1/2 inch plastic valve with a 5/8 plastic hose barb on it to the retun line in order to slow the water flow.
With less water flow on the ice I think I can make it last longer without affecting the cooling of the unit. Time will
tell if I am right. Run the wires from the pump up into the lid with the hoses.