Fuel Polishing

Larry M said:

I'm not sure I agree with the polishing/cleaning guy. Our tanks, each 350 gallons, has 3 baffles or 4 chambers. The fuel fill is at the high end, first chamber and the fuel outlet is at the low end, fourth chamber where the sludge/crap accumulates. I'm curious how they would create the type of turbulence required to get the sludge/crap at the other end of the tank past the 3 baffles?

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You have a point ! I will ask him to explain, bear in mind that baffles do not go all way to the bottom. There could even be a sump at one end as was the case in my sailboat and that would have to be vacced, I think. In any event, ALL you guys got me thinking and I appreciate that ... TX.

They generally use the pump output to stir up the fuel and sludge. The one I watched, the operator used a stiff but flexible line to fish it around the tank. He would thump into the baffle until he found a vent and go through. It was scary to see what lived in the bottom of the tank. I would have figured it was clean but he proved me wrong.

Here are 2 pictures of the baffles from inside of one of our tanks looking from the front inspection port toward the back on the port side. In the second one you can see the channel that the fuel flows from section to section. The curved section is against the hull.

We had tanks built for a previous boat. The baffle location was determined over coffee one morning. I have never seen 2 tanks built the same. KK4s's tanks around the same vintage, some had 2 baffles ours have 3. If you have seen the inside of one fuel tank, you have seen the inside of one fuel tank.

Be very careful. Do you have inspection ports? Nothing beats a good diaper cleaning. Nothing. He might be able to stir some stuff up, but he will never get anywhere near it all. Moreover, there is no way to tell what percentage he can remove. You will also (assuming you do have a lot of goop on the bottom) have clogged fuel filters soon after he is done. If he doesn't get 100% of it, the stuff that is left will still be floating around. Some will settle back to the tank floor, some will clog up your filter system. SO be ready.

And it will need it again later.

By far the best thing, if you have assess, is to get a professional tank cleaning. Then you have the peace of mind you need for a few years of safe boating.

YMMV

I guess you could use one of the USB boroscopes to drop into the fuel tank and see what is down there. I doubt you'd get it clean again, but $20 is cheap for what you'd get back.

Larry M said:

Here are 2 pictures of the baffles from inside of one of our tanks looking from the front inspection port toward the back on the port side. In the second one you can see the channel that the fuel flows from section to section. The curved section is against the hull.

We had tanks built for a previous boat. The baffle location was determined over coffee one morning. I have never seen 2 tanks built the same. KK4s's tanks around the same vintage, some had 2 baffles ours have 3. If you have seen the inside of one fuel tank, you have seen the inside of one fuel tank.

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Wow! That's some free hand cutting on a production boat...

One would have thought there might have been a pattern to cut from?

"Thanks, I agree with the filth in the tanks. I did finally speak to a polishing / cleaning guy here and he says that when they do it, they create enough turbulence in the tank that it will lift any debris in the tank and mix with fuel"

Does he represent the folks in Brooklyn with a fine old bridge for sale?