I wanted to be sure Carina had a clean tank before we started our Great Loop Cruise. As there was no clean out port, I decided to make one. I first had to gain access to the top of the tank so I installed a hatch in the bottom of the lazerett. I contacted Ezell MFG who (we thought) made the tank for advice on the actual port. They sold me a disc of 1/4” aluminum with 8 ¼” holes drilled around the edge and a cork gasket. Now all I had to do was cut the 4” hole in the top of the tank. As it turned out, they thought I had an aluminum tank but mine is polyethylene made by a previous vender no longer in business. They told me to go ahead but use self-tapping sheetmetal screws instead of bolts. I was concerned about the screws holding but decided to continue. I also decided to pre drill a smaller 9/64” hole and use regular sheetmetal screws thinking it would hold better in the poly.
Well, I finally got the nerve to cut the hole. It didn't take but 1/2 a jug of Captain Morgan! The polyethylene tank was much harder and thicker (1/4") than expected. The good thing about that was the 1/4" sheetmetal screws hold great. I can't strip them out by hand. I drilled out a 1 1/4" hole in the disc and a buddy welded on a "1/2 coupling" of 1" aluminum. The PVC plug finishes it off. I put Permatex 2 gasket sealer between the gasket and tank and on the end of the screws. Now, I can check fuel tank bottom samples and also check the fuel level with a gage stick marked at 5-gallon intervals, as my fuel gage was stuck in the full position. If I want to do a serious clean out, just remove 8 screws and take the plate off.
I was relieved and very surprised to find no water and almost no debris after I pumped 24 gallons of fuel out and through a Baja type filter. The tank had never been cleaned in 11 years. I shined a light into the tank and could see that the bottom was very clean. I’m a happy boat owner!
Hope this info is helpful,