We installed a fuel polishing system the week before Christmas 2000.

The work was split between Captain Zeb (who had done most of the wood repairs and enhancements on Dory), Captain Bill, and Bill’s son, Bill III.

The biggest problem was not what to do, but where to do it. A GB36 with twin Lehmans and a large old Onan doesn’t have all that much space! The installation itself was pretty straightforward.

The configuration has two groups of manifolds. The simpler one also has vacuum gauges so it’s easy to anticipate when filters need to be changed. This manifold allows me to send all fuel through the F1 (large Gulf Coast Filter) and then through the Racor. I can cut the F1 out of the system if necessary by turning a couple of valves. I can also shut down all fuel flow here if I want. If I want to, I can bypass both filters — probably useful only when transferring fuel from tank to tank. 

Because I want to be able to occasionally see these gauges while underway, I decided to mount this manifold on a bulkhead in the fwd head rather than some place in the engine room. Besides — there just ISN’T space in the engine room!

The second set of manifolds is really the “brains”. The fuel from all three tanks goes here, and is either shut off or routed to the filter manifold I mentioned above. What comes back from the filter manifold and what comes back from the engines — clean fuel — is then routed to the fuel tank from which it was taken (unless I am transferring fuel from one tank to another, which requires just a couple of valves to be turned). I can also isolate one or more engines if need be.

To put all these valves together where I can easily see that I have the return going to the supply tank, and where I can change tanks as I wish, suggested that the whole set be mounted together. The dealer suggested a layout to make it somewhat intuitive what went where, and supplied a sheet of marine plywood for mounting. We cut that down to about 15″ x 30″, and mounted the whole thing at the back of a cabinet under the sink, in the aft head. It’s also accessible underway without getting into the engine room, and it’s using otherwise unused space. Also, this was closest for running the many fuel lines to the manifolds. I used about 150 feet of fuel line — it would have been 500 feet or more if I mounted the manifold somewhere forward.

I had worried about the fuel hookups, but they were simple, once I had the manifold layout done. Find the fuel line going to each engine, intercept it, and substitute the new fuel supply line from the manifold. Find the return line coming from each engine, intercept it, and substitute the new fuel supply line to the manifold. Do the same for the tanks.  Done.  Then remove 50 pounds of old fuel line and valves at your leisure.

The only electrical connection was 12V to the continuous duty pump (via a 12 hour timer). This pump PULLS fuel via vacuum through the filter system, then PUSHES clean fuel to the engines, with excess clean fuel being returned to the tank. Running at anchor (engines shut down) just cleans fuel continuously. The pump takes a 5A fuse.

Finding space for the big F1 filter was tricky. It wants about 40″ vertically, for mounting plus clearance for changing filters.  There just wasn’t any such space. So Captain Zeb built up a mount forward of the genset, about centerline, and set the filter under the part of the cabin sole that will normally be lifted out when working in the engine room.

(We also put bypass filters on my engines and genset. That project was so simple that it doesn’t deserve a separate description. “T” off the oil pressure sender to get dirty oil, and return clean oil to the oil pan, using a replacement oil drain plug the dealer supplied. I had an inaccessible oil drain plug on one engine, and the dealer had 4-5 alternate solutions when I called.)

If I could have mounted everything together in the engine room, the job would have taken me under a day. If someone had done it before, probably 3-5 hours. But we spent about 30-40 hours, mostly because I split the system into pieces scattered all over the boat, to deal with space limitations, and to deal with my own goal of having easy access to all the valves while underway, without having to get into the engine room. It’s definitely a 2 person job if you are running fuel lines through bulkheads. Otherwise, one person is enough, I think.

The first 2 hours of running on the new system gave no surprises — it all worked as expected. You can see from the first filter change the junk that was in the fuel (at the bottom of the filter), and the clean pink look at the top, where only clean fuel has passed.

Oh yeah - the filter elements?  Bounty paper towels! (The oil filters use Scott tissues.)  

(Note to anyone considering this . . . check with me first. We discovered, years later, much better and more reliable methods.)