Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
What is the black, almost sooty build up in and around the fuel locker? Fumes going through a chemical change? And is there a preferred way to clean it up? And prevent it? A last philosophical question: Does trying to keep a boat clean ever end??
The best information I've found is that it's black mold. The theory is that it is propagated by ethanol in the gas. Scrubbing with bleach or with a household cleaner with bleach should remove most of it. I have heard that Concrobium will deter it from returning. I bought some to use this spring, but haven't tried it yet. I have seen Concrobium for sale in Lowes.
Incidentally, I have been using ethanol free gas for about the past 4-5 years and haven't had the problem. Here's a website that lists ethanol free gasoline stations all over the US. https://www.pure-gas.org/ Occasionally you can find it in marinas. I suggest you avoid using ethanol free gas from airports. I've heard avgas isn't good for small engines. Using ethanol free gas eliminates carburetor gumming problems during winter storage.
Steve Milby J/24 "Captiva Wind" previously C&C 35, Cal 25, C25 TR/FK, C22 Past Commodore
Edit: Didn't see Steve's post, I think he's got it covered!
I get it too. I've always wondered if it's some kind of mold because it only grows in the dark. Some people think it only forms with ethanol gas but I don't know if that's true either.
It cleans up pretty easy with Prism Polish, which I use to deoxydize the gelcoat in the cockpit.
Making sure your tank vent is closed when not in use should help, which is a good idea anyway.
Good luck.
Tim Keating 1985 C-25 TR/FK #4940 Midsummer Lake Don Pedro, CA
I started using Conchrobium a few years back after we had a basement flood. At the time my wife and I called Serv - Pro, ServiceMaster and a few more disaster cleanup places. They were all booked solid for a month. A very nice person who spoke with my wife said we can’t come out, but here’s what you should do: 1. Remove or pump out all the water - she said Yep 2. Remove all your waterlogged belongings - she said Yep again. 3. Run a dehumidifier and fans - Yep 4. Then go to the Home Center and rent a fogger and buy a jug of conchrobium. Put them together and run it for a while until everything that’s left gets coated. She said we’ll do it. 5. They also said to get a hand spray bottle of conchrobium for anything you missed You’ll never get any mold or mildew and the stuff is “natural” so it’ll won’t hurt you. She said, “so that’s your secret formula?” They said Yep and a lot of elbow grease.
Now I use it below decks everywhere: in the bilge, behind the drawers, inside the hatches and dumpster. I had never considered it for the black fuel grime in the fuel locker. Thanks - there’s another place I can use it.
First I spray conchrobium on the mildew and scrub with a nylon scrubber, then I spray with Clorox bathroom scrubber with bleach. Finally Fantastic. Tough spots get a little TSP slurry and a big rinse. Cleans up nice and stays clean for a few weeks.
FWIW, the soot/grime/stain was also on the outside of the hull, mostly in the vicinity of the fuel locker vent hole. Fortunately, it cleaned up pretty easily with boat wash on a wet microfiber cloth. I'll research this magic Conchrobium; never heard of it before now. Anything to make the job easier; inside the fuel locker is grim.
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.