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Better to Burn

What you need to know about fuel-polishing systems for your boat

The great thing about efficient boats is obviously that they don’t use much fuel to reach your cruising destination. The downside is that they can leave a lot of unused, prone-to-contamination fuel in your tanks. Owners of diesel-powered boats have long battled water and/or the growth of colonies of microorganisms that thrive in water and diesel fuel. Some people call these microbes algae but they’re actually bacteria, mold, and yeast. Whatever you call them, to keep them from clogging your fuel filters, you need to separate and then remove whatever water is in your fuel before the organisms can get a foothold.

A fuel-polishing system, such as this one by Reverso, helps ensure engines get pure fuel, resulting in a clean burn and fewer problems.

A fuel-polishing system, such as this one by Reverso, helps ensure engines get pure fuel, resulting in a clean burn and fewer problems.

The best way to get water—and the nasty stuff that comes with it—out of your boat’s fuel tank is with a fuel-polishing system. The technology has been around for a long time but only recently have owners of smaller craft—those down to about 40 feet LOA—started installing the systems on their boats. Companies such as Reverso Pumps, Algae-X, ESI Total Fuel Management, Gulf Coast Filters, Walker Engineering, and others offer their own versions but all of them essentially pump diesel fuel out of the tank, through a combination fuel-water separator and filter, and then back into the tank. Many companies that build polishing systems use separators from well-known companies like Racor and Separ.

“Price is primarily what kept [the commercial systems] from being used on smaller boats,” explains John Napurano, owner of Reverso Pumps in Fort Lauderdale. He says that large, complex systems similar to those on commercial vessels might make sense on yachts longer than 90 but they are impractical for anything smaller.

Essentially, a polisher cleans the fuel before it hits the engines’ fuel system. When a filter gets clogged on a boat without a polishing system, the fuel pump is starved, which can mean not only a burnt-up pump but an air-locked engine due to fuel starvation, or worse. When a polishing filter gets clogged, you simply replace the element. 

While Napurano generalizes that Reverso installs systems on boats from 40 to 80 feet, the size of the polisher actually has more to do with a boat’s fuel capacity than with its hull length. Many trawlers have larger fuel tanks per LOA because they’re intended for extended cruising, so you’d use a higher-capacity polisher on one than you might on a boat set up more for day cruising. Trawler companies such as Selene, Grand Banks, and Kadey-Krogen install polishing systems on most of their boats. 

Most polishing systems are rated according to gallons per hour (gph). For a 65-foot trawler carrying 2,000 gallons of fuel, Napurano recommends a 600-gph polishing system. Reverso’s most popular system is the 210 gph, which retails for $3,989 on the company’s Web site. The 210-gph kit is designed for a 110-volt A.C. electrical system and includes a mechanical timer and metal heat deflector. Gulf Coast Filters’ GCF-FPS-Deluxe Magnum is rated at 120 gph; the company recommends it for boats with fuel capacities greater than 500 gallons. 

One key to an effective polishing system installation is that it pick up the fuel as low as possible in the tank, which is where all the contamination accumulates. Another is timing. Napurano says the best time to polish your fuel is right after filling the tanks when the fuel is agitated. Think of it as shaking up a snow globe. Sediment and growth from the microorganisms that are resting on the bottom of the tank get stirred up during fueling. With debris and water dispersed throughout the tank, they get pulled more easily into the filters and out of your boat’s tank. You might need to change the filter element in the fuel-polishing system afterwards, but you’ll be ready to cruise with confidence knowing that all that diesel fuel is clean and ready to burn in the tanks of your efficient boat. 

(239) 690-9589.

ESI Total Fuel Management
(800) 411-3284.

Gulf Coast Filters Inc.
(866) 728-3582.

(954) 522-0882.

Walker Engineering
(818) 252-7788.

This article originally appeared in the February 2012 issue of Power & Motoryacht magazine.