Skip to main content

Dawn of the diesel outboard?

In a test run, a 2.3-liter prototype pulls its weight in fuel efficiency, power and noise levels

In a test run, a 2.3-liter prototype pulls its weight in fuel efficiency, power and noise levels

Glen Gardner and his son Don walked the floor of the Miami International Boat Show three years ago, taking in the big 4-stroke outboards. Mercury, Yamaha and Suzuki all had offerings of at least 250 hp.

“We started chatting back and forth and wondered why no one has come up with a diesel-powered outboard,” says Don Gardner, 27. “With today’s gas prices, it seemed crazy to us. After the show was over, we started researching the concept of a diesel outboard.”

Fast forward three years. The concept has become a reality. The Gardners and Glen’s good friend, Dean Clausen, have formed a company, Maritime Engineering Group ( ), and manufactured a 2.3-liter turbocharged prototype diesel outboard. A second test engine — a 3.0-liter model — should be completed this spring or early summer.

Actually, MEG’s prototype isn’t the world’s first diesel outboard. Yanmar introduced a 27-hp model in 1988, and a pair of them powered a 35-foot multihull across the Pacific. The MEG engine, however, is the first attempt to market a diesel outboard of significant size.

The Gardners and Clausen — all from the Fort Myers, Fla., area — worked most nights and weekends to get to this point. “It was a long and hard three years,” says Glen Gardner, 52, general manager of Gulf X Marina, which is owned by Clausen. “We took two steps forward and one step back, two steps forward and one back. There were some nights we were so frustrated that no one was talking to each other.”

They’re chatting it up now, though, hoping their 680-pound engine, the MEG Vision Turbo Diesel, will be a big hit in both the recreational and commercial boat markets. A full production version of the 3.0-liter engine should be ready by the summer of 2009. Both models are inline, 4-cylinder engines with 16-valve direct-acting double overhead cams. Shafts will be offered in 20-, 25- and 30-inch lengths.

The engine’s weight should not be an issue with new pleasure boats, which are having no problem handling the weight of other 4-strokes, like the Mercury Verado 350 SCi, which tips the scales at 667 pounds (30-inch shaft), and the Yamaha F350, which weighs 822 pounds (30-inch shaft).

The 2.3-liter engine delivers about 200 hp. They’ll be using the 3.0-liter engine for the higher-horsepower models. “The high-output version of the 3.0-liter motor will have twice the horsepower and torque of the 2.3-liter engine,” says Don Gardner.

The Gardners say their diesel is designed to run 8,000 hours at 80 percent power. How does that compare to a big 4-stroke? Although Honda could not provide formal longevity numbers based on testing, commercial owners of 225-hp Honda outboards have reported logging 8,000 hours, says Honda spokesman Brian Johnston. “These guys take meticulous care of their engines and use all factory parts,” he says.

Test time

During a test ride on HurricaneBay in Fort MyersBeach, the 2.3-liter prototype proved to be a quiet, powerful engine. At full throttle, it pushed a 22-foot Glassmaster — 2,750 pounds fully rigged and with full fuel — to a top speed of 34 mph. The fuel-burn rate was 6 gallons per hour. This translates to an eyebrow-raising 5.6 miles to the gallon.

How does that stack up against the 4-strokes in the 200-hp range? Yamaha performance bulletins — posted on the company’s Web site, — indicate the 200-hp Yamaha 4-stroke burns from 16 to 19 gallons per hour at full throttle. On a 22-foot Clearwater 2200 dual console (close in weight to the Glassmaster), a single 200-hp Yamaha burns 10.9 gallons per hour at 36 mph. This equates to 3.3 miles to the gallon — good but not in the same league as the diesel.

At high speeds, the diesel’s noise levels are similar to those of the big outboards. At top-end speeds the diesel came in at 90 to 92 decibels. Yamaha performance bulletins do not provide decibel readings, but other published reports indicate a 225-hp 4-stroke’s noise level is from 91 to 94 decibels at full blast.

At idle, the diesel’s noise level is about 70 decibels. At 1,000 rpm that figure increases to 72. The4-strokes have the diesel beat at these low-rpm settings, however. Noise levels for both the Yamaha and Honda 225-hp 4-strokes are 64 decibels at 1,000 rpm, according to published reports.

The prototype diesel uses a 225-hp Mercury OptiMax lower unit and a MerCruiser Bravo One four-blade stainless steel prop (22-inch pitch and 15-1/4-inch diameter). “We will not be using any Mercury parts in the future,” says Don Gardner. “We are currently designing our own lower unit and midsection. It will be state of the art and unlike anything on the market today.”

With three people on board, the diesel easily pushed the Glassmaster onto plane. At idle and trolling speeds, the engine vibrated, just as you’d expect from a diesel. No smoke or exhaust fumes were noticeable. The mechanical engine controls did clunk when shifting in and out of gear. The company will switch to electronic controls on future prototype and production models, says Don.

For now, MEG will remain a three-man team. Clausen worked closely with the Gardners in the beginning, helping with the concept of bringing a new outboard to market. Now, because of a busy schedule, he has become more of a silent partner.

Don Gardner brings a great deal of experience with diesels. For instance, he says, he worked for five years as a diesel exhaust emission engineer, helping to develop emission-treatment products (diesel particulate filters) that are currently used on all on-road diesel engines. His father spent 20 years as an automotive machinist, building engines to customer specifications and rebuilding cylinder heads of gasoline and diesel engines.

Mum’s the word

An outboard with a diesel’s durability should attract commercial operators and the military, says Gardner. Offshore recreational fishing boats in the 30- to 40-foot range also should be a prime market. He says the company has talked to a few recreational builders, but he declines to identify them. Until the company secures a patent for its engine, the Gardners will be tight-lipped about what’s under the cowling — and the specifics of their business.

The Gardners worked together to design the engine, using computer-aided software. An engine company in Florida actually manufactured it. The Gardners, again because of patent concerns, would not identify the company.

Ironically, the Gardners and Clausen have wanted nothing to do with diesel-propelled boats … when it’s time to have fun. Don runs a 2002 30-foot Motion SS (a racing cat) with twin 300X Mercury outboards, while Dad unwinds in a 1998 Formula 382 FAS3TECH with twin 500-hp Mercury sterndrives. Clausen owns a 50-foot aluminum Cougar, a former offshore raceboat that’s without power at the moment.