Fuel Polishing / Cleaning

[Pblais]

We had a nice event today at our small marina. We had a guy from a company that cleans fuel tanks. He did a few and it was interesting to watch and see the results.

The equipment was really pretty slick. The whole out fit it mounted to what looks like a tall luggage cart like the FedEx guys have. On the bottom was a nice tray to catch any spills plus an electric motor that pumps 400 gallons per hour. The hoses that go in the tank are just like you see at the corner fuel dock. The filter itself is about 9 inches in diameter and about 16 inches tall. The filter is fitted with a precut sheet of filter paper that is rolled on the inner cylinder and held by two quick release hose clamps. Fuels is pumped from the tank to the outside of the inner cylinder and forced through the paper to the inner side and out to the tank. It looks like a very large racor filter.

The first tank was a neighbors 2000 Bavaria 37. So it's not an old boat but it pulled out a bit of crud by the end of a few hours it was clear that the filter was nice and pink with just some thin film of gray on it. It took about 4 passes to get it clean.

The next boat was a 20 year old 35 ft Sea Sprite with a 19 gallon tank. My other neighbor only uses the engine to get out into the river for the local races and comes back. The fuel tank was half full and over 1 year old.

One of the features of this system is two pressure gages. One is the out bound pressure and the other the inbound. After it equalizes in a few seconds the out pressure is a bit over 30 lbs. The system is run for a period of time until the pressure drops to say 5 lbs. This boat ran the pump for about a minute and then the filter paper was changed. It was black solid with chunky bits. The next filter ran for 5 minutes before it too was changed but the color was very dark but not solid black. Filter 3 ran 20 minutes and now was gray but all the chunks were gone. Filter 4 started out at 30 lbs and held for about 20 minute then drops just a few pounds.

The last filter was gray because the dye in the fuel was pretty much dead. US fuel used off road has a red dye added at the factory so it can be sold road tax exempt.

It all points out that neither boat was really bad enough to not run but both tanks did accumulate a lot of crap. Dead algae, emulsified water and assorted bits of who knows what.

I have an aft tank that is very bad and it actually has almost no fuel but has sat a long time since before I got the boat. It appears the cheapest solution will be to add about 6 gallons of fuel and pump the heck out of it. the process they use is to place the hoses through the inspection ports not the fill tubes. The supply end is moved around so it becomes like a power washer inside the tank. At 400 gallons per hour 10 to 15 gallons gets recirculated and filtered pretty fast.

In this part of the world the cost is $75.00 US per hour without travel time but includes set up time. It includes all the materials (the filters and disposal). The show isn't a whole lot to watch as the final filters don't come out real dirty but they do tend to start getting at the hardest deposits. We were getting ready to take bets on how long each new filter would last so it's worth having a case of beer and a few friends over for the event. From what I saw a 7 year old tank showed enough deposits on the filter to make it seem worthwhile and a 20 year old tank with old fuel seemed very well worth it.

The important thing I learned is that for best results get the tank down low as it promotes more recycles through the filter paper and so catches more stuff quicker. It will save hours you don't have to pay for and you'll get a clean tank anyway. Adding new clean fuel to old fuel is better when there is less of it to dilute.

there is a company in Maine selling the gear to do this work as well as a smaller scale unit you can install in your boat, but I think for most sail boats having it done every 7 or so years would not be a bad idea. I had my other tank go real bad and strand me with too much algae bringing home after purchase. It's one of those things that really is impossible to survey unless you polish it.

[jdoe71]

I took a different route because from what I read the crud stuck to the walls of the tank doesn't necessarily get picked up by this method. My tank is 20 gallons and really easy to get at. I had the fuel pumped out by the marina and they disposed of it in their waste oil tank. Then I took my tank to a shop that cleans them, and they cleaned it out. I put it back in and filled it up with fresh fuel. cost was $65 to get the tank cleaned and $50 to get the fuel pumped out and recycled. Likely a lot cheaper than fuel polishing, which isn't available in my area anyway, and I know for sure the tank is clean. Probably going to make this an every 3 or 4 year maintenance deal.

[Roy M]

Why not pump the fuel through the filter into a drum, clean the tank, then repeat the pump through a filter back into the tank? I've watched the standard fuel polishing process many times on my neighbors boats and wondered why not do the most efficient method rather than the gradual process of filtering. I've also noticed that, unless you empty the tank, you can't be sure that all the crud is gone. My fuel tank is only 55 gallons. When it gets low enough, I pump out the final couple gallons into a jerry jug, wipe the tank down, inspect the fuel float, then filter the old stuff in a baja filter and cap off with fresh fuel. Wasn't Zeno's Paradox something like fuel polishing?

My fuel filter system reflects my paranoia of having a clogged filter as I make a tricky approach. I use two Racor 30 micron filters in parallel, with a selector switch choosing one or the other. Then the output fuel passes to a 2 micron filter which duplicates the filter on the Yanmar, but which is located in an awkward spot to service. Then, before arriving at the injector pump, I've tee'd off a hose to a Racor vacuum gauge located in the cockpit instrument panel. If I see the needle drifting into the red zone, I can hop below, switch filter banks, and feel relatively secure that I can get to the dirty bank in the near future. Later, I added the Racor vacuum switch at the gauge, allowing a buzzer to go off if no one is paying attention. One other touch: in the fuel line, after leaving the filters, I installed an outboard fuel squeeze pump. It removes air from the lines and helps bleed the system far faster than the "tickler" pump on the engine. I've installed variations of this system in customer's boats and none have reported any problems since. I just took mine to the extreme.

[Wildrice]

I made my own scavenging filter pump with parts purchased from Northern Tools (hydraulic and pressure pumps) it really is very easy, all you need is a hand cart, motor, pump like you have on a log splitter and two filter bases. Get some pipe wrench's and good sealant and go to work. It took me about two hours putting it together and have used it for many years and made lots of money cleaning elevator hydraulic oil tanks. I mostly filter 2 to 4 hundred gallons at a time and change the filters every other tank or so. Some of these tanks haven't been cleaned in forty years so you can tell how well the system works looks like brand new oil coming from the discharge end.

Keith

S/V Windigo

[cooper]

Why not have it on the boat as part of your normal operating system. Your main tank(s) get pumped (electric) through a filter into a day tank.the overflow from the day tank goes back to the main tank. The engine feed comes from the day tank using its normal pump and filter. The scrubber can run the whole time (when you turn on the ignition ) or with a float and bypass switch if you want to be fancy. l have two tanks (keel mounted) and this system allows me to filter into either (from one to the other) or back into the tank of origin. As an aside l can pump all into one if there is room so that my next fuel fill up is issolated (it just may need to be scrubbed before it can be used). At worst the day tank can gravity feed the engine......or the whole lot can be bypassed and the engine plumbed straight to an individual tank.

[Pblais]

Why not have it on the boat as part of your normal operating system.

The US Navy does this 24 x 7 even in port. They have a few more gallons than most folks do. Unless you have a lot of fuel I don't see the payback. At 1000 gallons you might want to consider it. Continuous filtering when you have say 50,000 gallons isn't really that many times through the filter even with say a 1000 gallons / hour pump that takes a long time. Reduced to the scale of a recreational boat your Racor does that much.

The real problem cleaning a tank is all the baffles and other places you need to get at. Just draining and filtering isn't usually enough as lots of deposits remain to grow the next generation. A good cleaning sytem replaces the fuel under pressure to force the sediments into suspension. The cleaning system I saw puts the fuel back at about 35 lbs pressure when the filter is not glogged. The pressure gage tells when the fuel is basically clean. They also move the return hose around inside the tank to get at as many corners as possible. That is why they like to have the tank with a low fuel level as it completes the job quicker. Just filtering the fuel isn't as effective. Your Racor filter can do that job already. If just replacing the fuel was as effective you could throw away 50 gallons cheaper than using a tank cleaning system.

If you have a small tank and can easily remove it then sending the old fuel to the recycle tank and cleaning it and replacing the fuel with new is cheaper. It's easy to the math. My neighbor only had a 20 gallon tank but would have had to cut the deck to remove it. If you can't easily get your tank out or it's very large then you can't do that. My forward tank was small and only had a small amount of fuel in it when it was terrible so we did pump the fuel and manually clean it and replaced with new fuel. For the aft tank I won't do that.

[cooper]

My tanks are built into the keel. Nothing like a good up wind slog to get the sediment moving about. The system is as much a fuel transfer and day tank system as a scrubber. The scrubbing part is an added bonus.

[GordMay]

The April/May (2008) issue of Professional BoatBuilder magazine has an article by Steve D’Antonio about Fuel Polishing:
Goto Issue 112, pages 100 thru’ 110:
Professional BoatBuilder - April/May 2008

[svstrider]

here is a link to a good article on fuel polishing from The Coastal Passage online magazine from OZ. The mag is always good reading although a bit rabid at times IMHO but what ever floats your boat. The latest addition is out now for free download. I tend to agree about trying to get the crud that is sticking to the tank sides. However maybe you could move your hose around.

BTW I have a feeling that Bob the previous editor lurks on the Cruisers Forum. Unfortunately if it is the guy I am thinking of he has gone to the dark side and is building a power cat - poor disallusioned fool.

How to clean diesel fuel tanks in boats

[s/v Jedi]

We designed and installed a new fuel system that supports polishing. I basically looked at systems in motoryachts like the Nordhavn and took note of all the features and smart ideas. Next, I selected the features I wanted and down-scaled it to sailboat dimensions. I used regular bronze 1/4" T's and fittings and miniature ball valves for fuel to make the manifolds. I use two small Walbro plunjer pumps for diesel that build pressure up to 7 psi which is safe for both Racor and the engine/genset.

Apart from polishing, the system allows: transfer, bleeding air, tapping clean filtered fuel, boost-mode, draining water/crud from tank-sumps, gravity-equalize tank levels, pumping & filtering fuel from jerry jugs or drum and help speed up Racor filter changes.

The cost of building your own system is low. I used two pumps @ $100 each and one extra Racor 500 filter. All the bronze parts cost next to nothing except the valves @ $8 each.

The system description, incl. diagrams and photo's is on our blog: s/v Jedi: A new fuel system for Jedi (English)

ciao!
Nick.

[ragdoll]

I like to run the generator when the seas are 6' or 7' , it returns about 20 time the fuel the yanmar 30 does and seems to make the yanmar filters last a lot longer. Never had a plugged filter on the yanmar, but several on the Gen.