DIY Fuel Polisher for Boat | Sailing Luna Sea | S4 E13 | Leopard 38 Catamaran 

Thanks, great information, and confirmation of what works and what doesn’t. Good to know about the ball valve and the need to have spares aboard. I don’t have the luxury of that space in my Southerly 135 engine bay so had to do a very compact version of your arrangement. So by using Banjo fittings front and back I was able to get the filters just 6mm apart with 3 way valves in between the Banjo fittings. The twin Raycor filters was the intended project and I designed custom sheet metal parts to hold it all together along with a third folded part to allow the whole assembly to swing out into free space at the side of the engine. So with this arrangement the filter selection valve makes it so you can select either filter, both, or none ie shut off fuel altogether. Then I added 3 other 3 way valves so the engine can run from a reserve tank (day tank or drum) in emergencies, and the return fuel is able to be diverted to which ever fuel source is being used. Then it dawned on me that I can make this assembly be a fuel polisher as well, so have a Marco UP3 pump coming which pumps 15 litres per minute (they have larger and smaller ones suitable for diesel and oil) so the final assembly will filter and water separate fuel for the engine, with a full selection range of filter and fuel source options, it will polish fuel in the main tanks and selectively reserve fuel drums of tank, and it will enable the transfer of fuel from tank to tank and tank to drum. The only thing this will not do is have different fuel filters in a row as your design does. This will have a vacuum pressure sender so that the line pressure can be seen from the helm or in the NMEA 2000 data transfer system. The final arrangement will have a light behind the filter bowls to make inspection in the dark engine bay easier. The whole assembly with the fuel pump is two and a half (plus a bit) times the width of the Raycor 500 filter body, and 30mm front and back deeper than the Filter body…plus the space the valve handles take up. Your video, though, gives me confidence that the system will work as intended. Looking up fuel line diameters for engine power, a 3/8 inch fuel line is good for up to 450 HP, so I will adjust the whole system to be suitable for up to 450 HP engines.

Great video mate

currently planning out my own polishing system using racor filters. they say to have the 2micron filter on the vacuum side of the pump so diesel is sucked through not pushed.

Great video. Never thought of 3 way valves so that you can do each tank. Do you use any type of biocide or treatment? Heading south from BVI to Granada next month.

Great video. Are you doing this on your cat? If so, you do this set up for both engines?, or just one set up for polishing from the fuel tanks? I'm looking at the RACOR 75900FHX. Not nearly as DIY as you. I have a Lagoon 46 and do not think I have a fuel polishing setup. Thanks!

Thank plan on doing to my 38

Excellent video. Been planning to build a polishing system on my boat and this looks like a great setup. Never thought of using gauges…. My initial thinking was along the lines of your initial setup. Need to upgrade my plan. With the knockoff Racor, what was the thread type on the one you used, NPT?

I just mounted one of the knock off racors last weekend. I ended up using hex-head through bolts. Sliding an open ended box wrench behind the unit and a socket on the other side, I could tighten it down.

You have in your video that guage placement isn't correct, would you mind detailing the exact placement of your guages?

If you mount filter to a board you will have easy access

pumps should always be pushing through a filter, why do you have it sucking through one and pushing through the other?