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Posted by on Feb 18, 2011 in Engines, News and Events, Outboard Engines, Powerboating, UK, US |

Seven Marine Reveals 557-HP Outboard at Miami Boat Show

Our Outboard Expert describes a new outboard motor powered by a supercharged Cadillac V8

UPDATE: The ferocious engine described below is waterborne as of February 2012, and Boats.com has had a ride. For a full report, see Seven Marine 557 Outboard: In-Water Debut.

Update, 2013: We finally saw some production models of the 557, and got them on video!

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A wild new 557-horsepower outboard motor from Seven Marine revealed on Thursday at the Miami International Boat Show appears to set new benchmarks for outboard power, technology, and price. Are you ready for a $70,000 outboard motor?

The Seven Marine team mounts 557 motors on the Intrepid 370 Cuddy.

The Seven Marine team mounts 557 motors on the Intrepid 370 Cuddy.

The 6.2-liter V8 outboard features an all-aluminum, supercharged powerhead sourced from GM Powertrain that is the same engine used in the Cadillac CTS-V automobile. It has closed cooling, a computer-controlled disc-clutch transmission with hydraulic shifting sourced from ZF Marine, and joystick control when paired with bow thrusters.

A pair of Seven Marine 557 motors were unveiled on the transom of an Intrepid 370 Cuddy, a boat that can be powered by triple 300-hp outboards. Other Intrepid models range up to 43 feet and can be rigged with four of the biggest outboards on the market. A pair of the Seven Marine 557 outboards could replace four 300- or 350-hp motors, offer about 300 less horsepower but also weigh 668 pounds less, and significantly reduce drag by placing only two gearcases in the water.

Seven Marine was founded about a year ago and is based in the Milwaukee suburb of Mequon, Wisconsin. Its principals include Rick Davis, who resigned in 2008 as executive vice president of advanced engineering at Mercury Marine. Davis is joined by his sons, Eric and Brian Davis, and manufacturing specialist Sandy Ballou.

Ready to roar: Twin 557's on the back of Intrepid's 370 Cuddy

Ready to roar: Twin 557's on the back of Intrepid's 370 Cuddy

In a video presented at the boat show, Rick Davis says that the concept for this new motor was hatched by Eric. According to media materials, Eric Davis holds 15 patents, the first of which was earned when he was 13 and on a “take your kid to work day” at Mercury. Eric Davis is also a champion powerboat racer, and the name of the company comes from his racing number.

The Seven 557 has a claimed dry weight of 1,000 pounds, compared to 667 pounds for a Mercury Verado 350 SCi. The top of the cowl is hinged and opens to reveal the V8 powerhead mounted horizontally, rather than in the usual vertical orientation. According to Rick Davis, the engine will remain in stock form as received from GM, with the exception of double-walled stainless steel exhaust and computer programming, and will run on 89 to 92 octane pump gas. I asked Eric Davis how the engine’s power made the 90-degree change in direction to mate to a drive shaft, and he just shrugged and smiled. “I’ll have to explain that to you later,” he said. Apparently the Seven team is not ready to reveal all of its secrets.

We do know that shifting is accomplished above the gearcase. The gearcase has a four-inch-diameter tube – a standard size – but has twin pinion gears to transfer power from the vertical drive shaft to the horizontal prop shaft, while keeping the size of the case small and hydrodynamic. An integral power steering system was developed with the input of Latham Marine, and the motor will be rigged with custom Hering propellers.

Rick Davis says the Seven 557 will have a three-year warranty, with 10 years of coverage against internal corrosion. How much will it cost? A cool $70,000 per motor, according to Eric Davis. You could buy the entire Cadillac for less.

Rick Davis told me that he and his team still have some testing and final calibration work to complete before we can actually take a boat powered by Seven 557 motors for a spin, and that work should be done this spring. In the mean time, I’m setting up a more-detailed tech briefing which I hope will answer some of the “how did they do that?” questions I’ve got about this exciting new motor. So stay tuned.

Charles Plueddeman

Editor’s Note: A year after this story was first published, the author made his first run with the Seven Marine outboard, reported in “Seven Marine Outboard: In-Water Debut” with accompanying video.

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