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We meet some very interesting people in our travels. Adjacent to us on the dock the other day were a couple of large sport fish boats from Trinidad and the owner of one of them happened to be a successful dealer for a popular brand of marine engines. After Michael struck up a conversation with him, he invited us on board his yacht and at our request, proceeded to share some info on engines. I was especially interested in his views on fuel management.

Our new friend told us that his boat carries 1700 gallons of diesel, a tad more than the 180 gallons that we carry on the Leopard. While touring his engine room, he showed us the two very large engines that power his boat (I forget the horsepower) and the big gen set that he runs 24/7 to operate his boat’s systems. Anyway, the point is, he goes through a lot of diesel!

So what did he have to say about fuel? Simply that, in the Caribbean, we are dealing with a fuel management problem as many times the fuel that we purchase is not very clean. That I knew! He also stated that, in his opinion, it doesn’t matter what the fuel is like in your tanks. Rather, the only thing that matters is how clean the fuel is that gets to your engines. That made a lot of sense to me. He shared that while many of his boating friends are stuck in the engine rooms making repairs, he is drinking rum and enjoying life. That made even more sense to me. 🙂

Filter Boss

To manage the fuel on his boat he had the diesel running through two separate dual Racor filter systems with vacuum gauges (similar to a Filter Boss — one dual system for each engine). He also had a fuel polisher which he ran (I can’t remember how often or long he ran that). What he recommended to us though, in addition to the dual Racor setup, was an item he called a centrifuge (here is one particular brand that I found during a Google search). While he did not have one of these installed on his boat because he has that polisher, his buddy, who was also part of this conversation, did. They both said that they have friends who have had very good success with these relatively new units. Apparently they are installed just before the primary Racor filters and have no replaceable parts. I’m curious to hear if any of our readers have experience which such a thing.


  1. I was once on a boat that had centrifuges prior to the cartridge fuel filters. It was essential as the fuel tanks were seawater compensated to eliminate free surface effect as well as provide ballast. We were feeding up to four LM2500 gas turbine engines (~33000 hp each) as well as three gas turbine generators. Closest we ever came to a major fire was when the gasket blew out on the cover, spraying fuel all over the aux machinery space (the watch covered it with foam to prevent it igniting).

    Haven’t dealt with centrifuges on any ship smaller than a Spruance class destroyer.

  2. My FIL ran strait vegetable oil in his power stroke pickup and tractor for a few years. Worked really well, and cost nothing. The pain in the ass factor was through the roof tho. They had to literally spend a weekend a month collecting and cleaning oil. But the filtering was pretty spectacular.

  3. Mike – I’ve got dual Racors on my boat, and a “home-grown” fuel polishing system. The fuel polishing system is simply a few bronze valves that you can use to select a “path” so that the fuel transits through the low pressure, low volume 12V pump – when required. Probably 3 or 4 times a year, I put the pump on for a period of time (at dockside it would be 24 hours, but on anchor, only during daylight hours) and this is more than adequate to circulate the fuel through one or more of the dual Racors. In other words, using the Racor filters for what they were designed for. Several months ago, this pump burned out and I’m bringing a replacement back down with me. The selection of the right pump is probably the most important element of any home grown fuel polishing system. By the way, I heard about Filter Boss, but it was at least 10 years after installing my dual Racor. They are quite expensive, but may be attractive if you’re starting from scratch, because the dual Racors are also pretty expensive.

  4. That is one neat and clean setup. Looks brand new and never used. Someone takes pride in their boat and proper maintenance. Cheers

  5. Mike,

    Annecodatal observation….On the submarine I served on, we used a centrifuge style oil/water separator on the oily, bilge water. It worked very well, we would store the oil for discharge back in port, and then pump the ‘cleaned’ water overboard. The oil that was reclaimed have no water left in it, the water had less than something like 10-15 ppm.

    Did you friend specify what process his polisher is using?

    here is an interesting site on the general subject

  6. Of course take that they say with a grain of salt, as they are clearly trying to sell their best system as well…

  7. Centifuges are common in laboratories and some industrial applications. They involve moving parts and appropriately sized motors to spin them. They are usually highly sensitive to movement or vibration as the fast moving separation plates etc can hit the fixed ones. There is also the risk of gyroscopic problems if the unit is moved. In the right circumstances they are good at separating fluids of different densities or suspended solids. By their nature they are not usually to be found on boats.

    Cyclones are different in that they usually have no moving parts. Unfortunately they are often called centrifuges as they perform a similar function though usually with less finesse. A properly set-up cyclone, designed for the job is usually highly reliable and will last ages with non-abrasive fluids. Ones for sorting grain or cement or other air driven ‘fluid’ particles will wear fast unless the flow is controlled by the medium itself.

    I have used centrifuges for small applications with some difficulties because of their sensitivity and speed. Cyclones on the other hand, used for big industrial purposes have been highly reliable.

    Technically, the unit you have highlighted is a cyclone I think and should be highly reliable too. The only example I have seen on a boat was on an old trawler, years ago, when they used a pump and a simple cyclone to separate oil and mess in the bilge water before pumping it overside and that worked well.

    I don’t know if that helps at all :-). I’m afraid it doesn’t directly answer your likely questions!



  8. Fuel centrifuges are pretty awesome…. and they last forever, I sometimes hear about units that have been in continuous service since the ’70s.

    Downside is, well, a nice Alfa Laval centrifuge to suit a 40-50ft yacht’s engine will cost about as much as the engine.

  9. many thanks for linking to our “the fuel purifier” (TFP) or separator.

    Although this TFP operates centrifugally—it is not a centrifuge.
    A centrifuge is usually motor driven and is a high speed precision device that subjects the fluids to huge centrifugal forces. Because they are high speed precision devices they are very effective, costly and prone to need servicing. Centrifuges work great when they are working. Fuel centrifuges are used mostly on very large vessels and workboats.
    The TFP has no moving parts—–and the only thing moving is the fuel going thru the TFP, because the fuel is introduced tangentially causing a cyclonic effect and using that force (from the fuel pump) to separate dirt and water which are usually heavier than the fuel making that separation fairly easy. The removed dirt/water is retained in the lower reservoir to be drained manually—by simply opening a valve and draining the junk out. The TFP operates within specific flow ranges–and there are sizes to accommodate almost any flow rate…so we size these based on the fuel pumps flow rate.
    We market the TFP as “the filterless filter” because it has no replacement filter elements, and is designed to protect the main filters—by doing some of the heavy lifting/separation prior to the main filters. The TFP will last forever or until you feed it some huge piece of junk that should have never been introduced to it. Proper sizing is important——but it’s a simple process we’d be glad to help with. It’s not smoke and mirrors or BS——-it’s a simple, effective and well proven technology that can protect your main filters and extend their lifespan.

  10. Check out DieselCraft, I have used their motor oil centrifuges on a few of my diesel trucks, I was able to go 10k miles between oil changes rather than 3k. I know they also make a model that polishes diesel before it is enters into the engine. For my fuel (waste cooking oil) I use a larger centrifuge to clean up the fuel before it is pour in the tank. The centrifuge spins a 6k RPM, you would be amazed work comes out of relatively clean looking fuel at just one pass through the centrifuge. The larger centrifuge is made by WVODesigns. Clean/Dry fuel will keep your diesel engine happy.

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