Seven Marine 557: Biggest Outboard Engines Sea Trial

The matte-black Midnight Express 39 Open with a matching trio of Seven 557 outboard is running in the upper 80 MPH range, according to Midnight Express.

14th March 2013.
By Charles Plueddeman

Our video of the Seven Marine 557 hp outboards was taken on a 38 Fountain at the Miami Boat Show, but at the show I was also ogling a Seven Marine-powered Midnight Express 39 Open—which was spied undergoing sea trials on Biscayne Bay last week. According to Midnight Express, this trio of 557-hp supercharged V8 outboards are from the first Seven Marine production run, and so far Midnight Express and its Miami-based client are very pleased with the results.

The Midnight Express 39 Open, in sea trials on Biscayne Bay off Miami in early March.

“We are running in the high 80s with this boat, which we are ecstatic about,” said Midnight vice president Eric Glaser. “This is the fastest boat in its class that we know about.”

Glaser told me that they typically rig this boat with triple Mercury Verado 300 outboards, a set-up that’s good for about 60 mph top speed. A quad rig of Verado 300 motors is good for about 70 mph on the Midnight Express 39 Open, according to Glaser.

There has been some gossip that Seven has had durability issues with the outboard’s twin-pinion gearcase, but Glaser’s not buying that.

“As far as the gearcase goes, it is modeled after a (Mercury Racing) 6 drive, which is rated for much more that 557 horsepower,” says Glaser. “I don’t believe they have ever had a problem with one yet and from what I can tell, they won’t ever have a problem. It feels rock solid. If it will fail, the customer that owns the black boat will be the one to break it. He runs the boat beyond hard. All he knows is full throttle.”

Glaser added that this boat is rigged with the Seven Marine/ZF Smart Command 5000 joystick control, which works in combination with a bow thrusters and was “easy to install and set up.”

Seven Marine was planning to be in production and shipping motors at the end of last summer, but as is typical with any start-up, “We encountered some issues that we did not fully anticipate,” said Seven Marine President Rick Davis at the Miami show. “We had to bring the supply base along.”

One key hurdle was cleared just last month, according to Davis, when Seven received an EPA emissions compliance ticket, which clears the motors for sale in the U. S. Davis told me there was never any doubt the motors would pass emissions testing, it’s just a process that takes some time.

Seven Marine debuted at the Miami Boat Show in 2011 with a prototype that stunned the show. The motor uses a 6.2-liter supercharged/intercooled V8 sourced from General Motors as its powerhead, is rated at 557 horsepower, and carries a price tag of $70,000. Last year Seven had a boat in the water with a single prototype motor and offered demo rides.

Since last year, Seven has made some changes to the motor to make it easier to service and to improve airflow to the powerhead. Testing revealed that the original air induction path was not able to flow the required 1,000 CFM (cubic feet per minute) the engine requires at full power, according to Davis. The current motor has a much larger intake on the upper rear of the cowl, covered with stainless-steel mesh, and a new patented water-separation system on the intake.

seven marine access port

The remote oil filter (top), dropcase cover and water pump (bottom) are accessible when the rear service panel is removed from the Seven Marine 557 outboard.

The original location of the oil filter on the engine block was also inconvenient for service, so it was relocated to the rear of the engine, and can now be reached by popping off the rear section of the cowl. Also located below this cover is the drop-case that mates the powerhead to a hydraulic-shifting ZF transmission. Within the case are a set of helical-cut gears that can be changed out to achieve the desired final-drive ratio, a much faster and easier process than changing the lower unit. Right below the drop-case is a service cover for the water pump.

One cool aspect of the Seven Marine display in Miami was a steel structure holding nine of the V8 engines that power the Seven outboard. This is the same racking used by General Motors to ship the engines to Seven, although it was painted for the show.

Seven Marine has also begun setting up a service network, with seven centers in Florida, one in Louisiana, and one in the United Arab Emirates.

For more information, visit Seven Marine.


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About the author:

Charles Plueddeman

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Charles Plueddeman is Boats.com's outboard, trailer, and PWC expert. He is a former editor at Boating Magazine and contributor to many national publications since 1986.

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