Unexcused Absences

When we were refitting our 1976 Gulfstar trawler a couple years ago, I wanted to replace the inefficient fuel filtering and distribution system that was the original equipment on the boat. Inefficient, because each of the two main engines, plus the generator, had their own fuel pickups, plus their own primary filters. This meant lots of pipe fittings and crossing hoses and filters that, if they clogged, required shutting down the engine to replace. Imagine being underway in a tricky situation and having an engine fail from a clogged filter (fuel filters never seem to clog when parked at anchor or at a dock).

The ideal setup is to have a single fuel pickup, then route a single fuel line from there into a pair of filters with a selector handle so that if one filter clogs, you can immediately switch to the “clean” filter and continue running while you replace the clogged filter at your leisure (ideally when parked at anchor or at a dock). From the filter the output then routes through a manifold that distributes fuel to each of the engines.

My choice came down to a setup from Defender that consists of a pair of Racor 500 filters with selector handle and analog vacuum gauge (about $750), or a FilterBoss system that’s basically the same setup but adds a circulating pump for fuel polishing, an LED that backlights the glass bowls on the Racors, and a remote digital readout of the vacuum gauge (about $2,300).

Dual Racor Fuel Filter from Defender

FilterBoss Commander from KTI Systems

The high price of the FilterBoss initially steered me towards the Defender product, but I really liked the idea of an integrated fuel polishing system. After further reflection, plus discussions with knowledgeable marine mechanics, I decided that fuel polishing system was an unnecessary luxury, for the following reasons.

The main selling point of an integrated fuel polishing system is that you can run the pump to circulate your fuel through the primary filter with the flick of a switch, any time the boat is at rest. This way, the manufacturers claim, you will always have a clean tank of fuel. The main flaw with this logic, though, is that the grime in a fuel tank settles to the bottom, and only gets stirred up once the boat is underway. So polishing your fuel at a dock will at best give you a false sense of security.

The best time to polish your fuel is when your boat is out and underway, when wakes and chop act to stir up the sediment and it gets sucked into the fuel pickup and from there into your filters. Since most diesel engines have a return line from the injectors back to the fuel tank, some fuel is returning to the tank whenever the engines are running, and thus is in effect polishing your fuel whenever you are underway, which is the ideal time for that procedure.

*Update, July 2017 – we picked up a load of dirty fuel in the Bahamas, and discovered the partially clogged filter in the middle of our 4-day cruise home from the elevated reading on the vacuum gage. Switching to a clean filter was as simple as turning the yellow handle. I was able to then change the clogged filter at my leisure once the engine room had cooled down.

The Bottom Line – 5 out of 5 for Defender’s Dual Racor System

I ended up purchasing the Defender dual Racor system for less than 1/3 the cost of the FilterBoss, and I couldn’t be happier. The vacuum gauge has a little “max” needle that shows the maximum travel of the main arm, so I don’t have to check the gauge while the engine is running. The selector lever can switch between “Left”, “Right”, “Both”, and “Off”. Racor filter elements are inexpensive and are available wherever there is boating activity. That, plus I saved over $1500 for some bells and whistles that really aren’t necessary.

Dual Racor from Defender PROS:

• Simple to change filters while underway with no interruption to fuel flow
• Replacement filter cartridges are readily available world-wide
• Great price at around $750

Dual Racor from Defender CONS:

• The vacuum gauge can only be read head-on; if it were mounted a little higher the gauge could be turned to view at any angle
• Minor nit-pick; the selector handle is not labeled. “Left” and “Right” are obvious, but “Both” and “Off” are not

FilterBoss from KTI PROS:

• Remote readout allows user to check filter status from the helm
• Integrated pump for fuel polishing may eliminate need for an engine-mounted lift pump in certain circumstances

FilterBoss from KTI CONS:

• Expensive; the $1500 extra for dock-side fuel polishing is hard to justify, especially since fuel is polished while underway in most diesel engines
• Bulkier than Defender’s dual filter; if space is a premium in your engine room, it might be tough to mount