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All Mixed Up
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Here's a look at the realities, myths and misconceptions associated with the new ethanol-blend fuels.
By Capt. Vincent Daniello
It should have been an idyllic Florida Keys vacation. With the boat loaded and lunch packed, my wife and I ventured offshore. We made it only two miles before the first engine died. While cajoling the sputtering outboards back to the dock, I identified the culprit. My brotherin- law had just filled the 30-foot Pro-Line's fuel tank, and the marina where he filled the tank had recently switched to E10 — the mixture of gasoline blended with 10 percent ethanol that has been making its way around the country.
I thought I knew the issues with ethanol. Instead, I've found they don't fit into the concise paragraphs we read in magazines. Complexities of boat systems, differences in climate and even local variations in fuel all seem to harbor odd and unforeseeable obstacles when gasoline and ethanol are mixed. With sensible precautions, the vast majority of boaters experience few problems when switching to E10 fuel, but that's little comfort to those who do have issues. Instances of unusual problems deserve a closer look, particularly with the specter of E15 — 15 percent ethanol — looming on the horizon.
In my case, there were no signs of phase separation or filters clogged with debris loosened from the tank by ethanol. Instead, the engines' fuel hoses had delaminated; the interior liners were flaking off in large chunks, rapidly clogging the filters. The problem occurred only in the few feet of hose supplied by Mercury with the engines, but identical fuel hoses supplied by Mercury on other new boats around the country hadn't shown problems with ethanol. Based on all I knew of E10, this shouldn't have happened on a boat built in 2000. But it did, and I quickly learned the problem bordered on epidemic in parts of South Florida and the Keys. "They mandated this ethanol fuel here [last winter], about the time we started seeing this issue," says Jim Lawrence of J & B Mobile Marine in Tavernier, Florida. "Now I see it on a weekly basis, sometimes two or three times in a week." Lawrence says many of his competitors along the island chain experienced similar hose failures. Other mechanics in southeastern Florida report significant instances of hose delamination as well, on boats built as recently as 2007, across a wide range of outboard engine brands. The problem doesn't seem to affect fuel lines within the boat, which don't have the flexibility requirements of hoses that connect to outboards and are therefore manufactured differently.
Phone calls to several mechanics as far north as New England turned up other problems: corrosion-proof coatings peeling from inside vapor separator tanks, aluminum carburetor bowls deteriorating, fuel filters clogged with white paste from aluminum tanks. The list goes on, but many issues seemed to crop up only in small pockets or sometimes even as chronic failures on a single boat that hadn't had problems before switching to E10. I found another rash of hose delaminations in Long Island, New York, in boats that had been running E10 without issue for years. Then the problem disappeared just as quickly as it came. The more I learned about ethanol, the less I knew. True, ethanol is a powerful solvent, scouring years of gasoline varnish off the insides of fuel tanks and systems, causing clogged fuel filters, but no mechanics reported this as a major issue. Ethanol dissolving rubber and plastic hoses and components on older boats came up a few times, but most of those parts had been changed during routine maintenance years ago. More common complaints focus on ethanol fostering the corrosion of aluminum fuel system parts and aluminum fuel tanks. One boat in Long Island went through seven vapor separator tanks in five years. Another has had four fuel pump failures, but only on one engine — the pump on the other engine was fine.
Many of these problems could be a result of ethanol's affinity for water. E10 fuel will absorb a small amount of water, holding it suspended within the gasoline until it is burned harmlessly in the engine. But add enough water and it will instead absorb the ethanol from the fuel, called phase separation. The resulting ethanol and water cocktail — expanding from two to eight times the original water volume — is a much stronger solvent and corrosive agent than either ethanol or water alone and a likely cause of damaged fuel system components.
But my brother-in-law's fuel tank and filter showed no signs of phase separation. Mechanics I spoke with in Florida and New York know the signs of phase separation and didn't see it as an explanation for their hose delaminations either. Armed with clear patterns of failures, I went to fuel and engine experts for answers.
"I think it might be a localized phenomenon," says Frank Kelley, Mercury Marine's fuel and lubricant specialist. "Not a bulk phase separation [within the fuel tank], but a cell setup where you get localized phase separation." By this theory, phase separation can occur within fuel hoses themselves or even within vapor separators, carburetors or fuel pumps. "The combination of water and ethanol is very corrosive," says Kelley. "Some of the aromatic compounds come out [of the gasoline] as well. You're getting a concentration of all the things that damage polymers."
But how could fuel separate in one part of a fuel system and not another? "Phase separation is temperaturedependent," says Fred Ruhland, ValvTect's vice president of technology. "You can have homogenous fuel at 80 degrees, but phase separation at 70." Ruhland also says the specific hydrocarbon makeup of the gasoline — due to differences in both crude oil and refining — alters the amount of water needed to cause separation, sometimes well below the 0.5 percent threshold most often cited. Fuel at the verge of separating might cool within a rubber hose or fuel filter faster than in the fuel tank, and differences in the underlying fuel chemistry of local supplies may explain the patchwork nature of some of these problems. Add to that the fact that ethanol actually draws moisture out of the air, particularly in rainy or humid climates. "You could be halfway there with the fuel as it is delivered to you," Ruhland says. "If you add even a small amount of water, you're at the threshold of phase separation."
If water is the mechanism for ethanol damage, then the solutions are known. Clean all water out of tanks before filling with E10. Keep tanks nearly full to avoid both condensation and absorption of moisture directly from humid air trapped above the fuel in the tank. Inspect fuel fill cap seals and fuel tank vents, and use a fuel stabilizer formulated for ethanol. Kelley, Ruhland and other fuel experts also say gasoline doesn't contain as aggressive an additive package as it has in years past. EPA standards set in 1995 require fewer additives than most gas companies were already putting in their fuel, and these additives are now further diluted by 10 percent ethanol.
Fuel stabilizers can't prevent phase separation, but they raise, slightly, the threshold at which it occurs, allowing fuel to tolerate just a bit more moisture or greater temperature changes. Major brands have been reformulated to help with ethanol. Gold Eagle's STA-BIL Marine Formula has quadruple the detergents to keep fuel systems clean and double the cosolvents to stabilize fuel against water or temperature changes. The marine formula also doubles corrosion inhibitors that coat metal fuel system parts, plus more antioxidants to stabilize fuel when exposed to air. Power Research Inc. reformulated its PRI-G stabilizer when E10 became widespread, as did ValvTect. Both products are similar to STABIL in that all are petrochemicalbased. Star brite's Star Tron works a bit differently. Enzymes break the bonds between water and alcohol, separating water into microscopic droplets that can either stay suspended in fuel until burned or fall out to the bottom of the tank. Each major brand has its own following. "Use what you want but know what you're using," cautions Bill Lindsey of Star brite. "If it is alcohol-based, you don't want to add anything above 10 percent alcohol in E10, or you risk voiding your warranty."
ValvTect distributes fuel to marinas with stabilizer already added, but the company also controls ethanolrelated problems at the pump, inspecting marina tanks annually in the north and biannually in the south to mitigate problems. Valv- Tect dealers are also required to have filters that swell with moisture to stop fuel flow before it reaches boats. "We're attacking the problems from the mechanical side and the additive side," Ruhland says. "We've been doing this in Chicago [with E10] since the mid-1990s, and it has become almost a nonproblem." While these precautions are taken at many other marinas, aren't common. Rigid quality control ensures they're in place at certified ValvTect marinas.
Much has been written about the theoretical 3 percent reduction in fuel economy expected because ethanol doesn't store as much energy as gasoline. Now questioning everything I'd read and written about ethanol, I tested a 150 hp Mercury Verado rigged to run off of two portable tanks — one containing E10 and the other unblended gasoline. Rigging was done by Shep Brown's Boat Basin near my home in New Hampshire with input from Mercury engineers.
Economy did fall off with E10, but the differences were greater at slow speeds, with only a 1 percent drop near wide-open throttle; 0 to 30 mph times were off by a little over a tenth of a second — about 2 percent. While I expected a noticeable drop in rpm at maximum throttle, ethanol only dropped 10 rpm from gasoline. That didn't surprise Steve Miller, Mercury's brand manager for all outboards over 75 hp. "We have horsepower, torque and fuel burn targets we're trying to achieve, with one of the parameters being the fuel could contain up to 10 percent ethanol," Miller says. "Straight gasoline has a little more energy, which might give you a little better torque, so your acceleration is going to fall off [with ethanol]."
Tim Reid, director of engine design and development for both Mercury and MerCruiser, expects about the same from inboards and stern-drives. "We're calibrating our engines slightly richer to protect the customer who burns E10," Reid says. His concern stems from oxygen molecules within the ethanol itself, which don't exist in unblended gasoline. While automobile engines sense oxygen levels in their exhaust and adjust incoming fuel accordingly, marine engines aren't as sophisticated. The predetermined ratio of fuel and air entering a marine engine means E10 fuel contains more oxygen and less burnable fuel. This "leaner" mixture burns hotter and longer, raising cylinder and exhaust temperatures. Mercury and other manufacturers add a bit more fuel, making the mixture "richer," to cool things down with E10. This wastes fuel when burning straight gasoline, accounting for the narrow economy differences between the two fuels.
With this realization, and with E15 currently being pressed as the next wave of biofuel, my conversation with Reid shifted. "With E15 or E20, we'd have to add even more fuel for the occasional customer using it," Reid says. The problem is that today's engines are tuned for only E10, and retrofitting them won't be simple. Reid is also concerned about older engines, which ran a little richer back when gas consumption wasn't as important. "We used up those margins when we went to E10," he says. "We're pretty confident the [older engines are] safe with E10, but the jump to E15 or E20 will be much harder. We're data-poor on what the change might mean."
Other less tangible concerns come up regarding ethanol. Problems in Florida, for example, are often blamed on "over-blending," the term used when too much ethanol is added at the time the fuel is mixed. Yet for all of the allegations, I couldn't find a single firsthand account. A Florida classaction lawsuit claiming damage due to over-blending quietly disappeared. Even widely reported allegations that too much ethanol in fuel shut down 70 Baltimore police cars one morning this September couldn't be confirmed by city attorneys working the case.
Gasoline itself isn't uniform, varying chemically as it comes from each refinery in the United States or abroad. One known problem with E10 — sulfur in gasoline mixing with water in blended fuel becomes corrosive sulfuric acid — has been corrected with tighter sulfur regulation. But what other interactions might cause localized problems? Ethanol is also imported, coming to the U.S. from Brazil and several Caribbean nations where it is distilled from sugar cane, not corn.
BoatU.S. and the National Marine Manufacturers Association are both lobbying the Environmental Protection Agency to proceed cautiously before allowing E15, as are groups as varied as the Sierra Club and the National Meat Association. BoatU.S. believes more than 30,000 comments were submitted to the EPA by the marine community during the public comment period before the E15 decision in December, including one from the U.S. Coast Guard. "We have anecdotal evidence that ethanol may contribute to accelerated deterioration and failure of various compounds in the fuel systems of recreational boats," writes Rear Adm. Kevin S. Cook in a letter to the EPA in July 2009. Cook's concerns include new and older boats, both with E10 and particularly E15. He continues: "Only very limited testing on ethanol-blended fuels has been conducted relative to longterm safety and durability issues. We feel strongly that, to ensure the continued safety of recreational boaters, an in-depth technical evaluation must be conducted." As with most groups, the Coast Guard isn't denouncing E15, but is simply saying concerns over current problems with E10 should counsel caution before proceeding to higher blends.
Many of the sources interviewed for this article caution against alarm, since most boaters transitioned to ethanol without incident. Even before E10 came along, the complexities of boats had produced occasional inexplicable problems. "Once in a while you'll hear about something and you wonder, 'Is that really ethanol, or is that a mechanic blaming ethanol when he really has no idea?'" says Bob Adriance, BoatU.S.'s technical director.
"I think [many] people who've had problems just put ethanol in and said, 'Let's see what happens,'" Kelley says. "They have to be more aware: check hoses, check filters, take a proactive approach." These admonitions are valid, but even following the best advice on preparing for ethanol may not have prevented my ruined Keys vacation. The truth about ethanol, it seems, has yet to be written.
Other Boatkeeper tips featured this month:
- More Electronics from past issues.
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