Plastic Sheet over gas tank

[floater]

Ever since I pulled up the floor on my 88 Revenge 20 WT I notice the top of the gas tank is always wet and mouldy. I've resealed all the caulking twice now but water still seems to get in some how. If I were to pull up the floor again and seal a thick plastic sheet over top of the tank would there be any problems? Of course I would dry it out first. Thanks

[Phil T]

I would not do this.

Every time the boat is not in use, pull off the inspection ports and let the cavity air out.

[floater]

Ya thought so. I've tried leaving the inspection ports off for days on end and the top of the tank still looks 'gooey'. Looks like lots of water is getting in from somewhere. Thanks

[jimh]

When your REVENGE is not in use, and if it is stored in a location where rain won't be able to get into the cockpit, then you should open the circular pry-out covers in the deck to allow better air circulation above the central fuel tank cavity.

Below the helm area of a REVENGE there is an access cut-out for cable to exit the rigging tunnel. Normally this cut-out is surrounded by a small molded plastic dam or raised lip that helps to prevent any water on the deck from being able to flow into the rigging tunnel. This does not allow direct passage to the center fuel tank cavity, but if the water level becomes high in the rigging tunnel, water can flow into the fuel tank cavity through an access hole in the aft Starboard side of the cavity wall. Check to see if that plastic lip is still in place and intact.

The fuel filler hose on the Port side of the cabin superstructure also runs through a large access hole in the deck. Water could be getting into the tank cavity there. Of course, water can get into the cavity through the four deck plates if their O-ring seals are not sealing well.

If the top of the fuel tank has some sort of residue or gooey substance, that is not normal. The tank top started out as clean aluminum with typically a green anti-corrosion coating, probably a zinc-chromate primer paint common with aluminum components.

[floater]

The 'slit' cavity under the console has the lip and there is no evidence of any water stains under there. The circular deck access covers are all in great shape. This all started after pulling up the floor last season. I'm going to be pulling up the floor again soon to replace the fuel inlet and vent hoses with Ethanol Resistant ones. Once I get it opened up I'm going to scrub clean the top of the tank and spray it with some Clear Coat to try and protect it from any further water ingress. I will redo all the caulking around the floor after reinstalling it. Any idea what that square access port is for on the Starboard side right under the drivers seat against the side? I've removed that cover and didn't find anything under there.

[jimh]

The smaller square deck cover on the starboard side near the helm of a REVENGE model covers what is probably used on other models that share that hull as a pathway to the center console for electrical conductors, such as the wiring to the sidelight lamps or something similar, or engine harnesses, or other control lines that can't run in the rigging tunnel.

[floater]

Thanks Jimh. Gonna start the floor job soon.