Power Couple

The integration of Volvo Penta’s DuoProp system with powerful Seven Marine outboards makes it possible to push large boats more efficiently at all speeds
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It looked like an answer to a question nobody was really asking. In 2011, a start-up called Seven Marine revealed the prototype for a 557-hp supercharged V-8 outboard that would weigh more than 1,000 pounds and cost more than $80,000. It was hot rod engineering extraordinaire and a highlight of the Miami International Boat Show, where a crowd 10 deep gathered to see the polished stainless steel exhaust gleaming beneath the open cowl. So very cool, everyone agreed, but who would ever buy such a beast? The industry consensus was that Seven Marine had created an outboard with no viable business plan.

Fast forward to Miami 2019. A shoulder-to-shoulder crowd had gathered again, this time for the debut of the Tiara Sport 38 LS, a day cruiser designed for outboards. On the transom hung a pair of Seven Marine motors. Leading the presentation was Ron Huibers, CEO of Volvo Penta of the Americas and now chairman of Seven Marine, and he had a business plan.

American boat buyers have rediscovered the outboard motor, especially the more powerful models. According to the National Marine Manufacturers Association, sales of outboards over 200 hp have increased by 68 percent since 2014, and sales of those rated over 300 hp have grown at a double-digit pace annually since 2013. Since the Seven Marine 557 went into production in 2013, Mercury Marine has introduced 400-hp Verado models, Suzuki has launched its 350-hp DF350 with dual propellers, and Yamaha has delivered a 425-hp XTO outboard. These mega-motors are powering pontoon boats, center consoles and catamarans. Four, five and even six outboards racked on one transom are powering boats more than 50 feet in length from a number of production builders, and outboards are proliferating in markets once dominated by sterndrives.

An outboard motor has always offered a number of advantages over inboard power: a better power-to-weight ratio; ease of maintenance and winterization; quieter operation with less vibration because the engine is not in the boat, and the ability to tilt clear of the water to avoid marine growth when the boat is moored. Now, those advantages are available at power ratings that exceed the most powerful gas inboards.

Volvo Penta’s 2017 acquisition of Seven Marine was validation of these concepts. It also brought the engine behemoth back into the outboard game and gave Seven Marine a major boost.

The Seven Marine origin story began in 2009. Rick Davis, now 67, had wrapped up a 32-year career in the marine engine industry, retiring as chief technology officer at Mercury Marine. He started a consulting firm, Davis Engineering, in the Milwaukee, Wisconsin, suburb of Germantown with his son Eric. It was Eric who, upon observing boats powered by triple and quad outboards, proposed that a pair of more powerful outboards made more sense. Eric put together a computer-assisted design concept using a Mercury Racing V-8 engine, a Zeus pod drive transmission and a Mercury Racing lower unit. “I kept presenting him with problems to solve, and he kept coming back with solutions,” Rick Davis says. “Eventually, I decided it might really work.”

The Tiara Sport 38 LS is rigged with a pair of new Seven Marine 527 outboards fitted with a Volvo Penta  DuoProp gearcase.

The Tiara Sport 38 LS is rigged with a pair of new Seven Marine 527 outboards fitted with a Volvo Penta DuoProp gearcase.

Younger brother Brian Davis, an engineer working in software sales, joined the team in 2010 and began presenting the outboard concept on paper to boatbuilders. Encouraged by the response, the Davis crew recruited investors and began the work of turning the concept into real hardware. The number on Eric’s racing kart was 7, hence the name Seven Marine.

The resulting Seven Marine 557 created the template for future models, powered by a supercharged version of the General Motors Gen IV 6.2-liter V-8 engine produced for Cadillacs. The engine was mounted horizontally and mated through a multigear transfer case to a ZF Marine transmission located below the engine. This transmission had a vertical output shaft and was designed for a smaller Zeus pod drive that never made it to production. It was sitting on the shelf at ZF in what became a lucky break, according to Rick Davis, who says he never could have financed its design from scratch.

Creating this outboard and the business to support it was a tremendous undertaking that was not without setbacks. When it was ready for sale in 2013, the Seven Marine 557 had two things going for it: boutique exclusivity and a huge horsepower rating previously limited to exotic sterndrive power. Both things appealed to well-heeled boaters around the world. “We were market disruptors,” says Brian Davis, “and were years ahead of the established market. In 2013, there were only 15 boat models in the world over 40 feet in length designed for outboard power. Today, there are approximately 300 models in that segment. The top of the price point for an outboard-powered boat moved from $350,000 to $2 million to $4 million. We moved that market forward.”

As it ramped up, Seven Marine added a 627-hp model and built a service network. The Davis family made it work, but a partner like Volvo Penta could add a worldwide network for service and parts, testing resources, and the scale to support expansion. And in the eyes of mainstream boatbuilders, the association with Volvo Penta could position Seven Marine as a major player in the engine market.

The influence of Volvo Penta was on display at that 2019 Miami International Boat Show unveiling. The outboards rigged on the Tiara Sport 38 LS were a new Seven Marine 527 model fitted with a Volvo Penta DuoProp gearcase.

Volvo Penta does not publish a price for Seven Marine outboards, as they are sold directly to boatbuilders, but the Tiara’s base price with the Seven Marine package was $623,725.

That package includes a full suite of Volvo Penta Electronic Vessel Control features such as joystick driving and docking, and a Volvo Penta-Garmin integrated Glass Cockpit with autopilot, dynamic positioning and Easy Connect remote connectivity through an app.

The EVC system has been modified to communicate directly with the Seven Marine outboards, and does not require an interface patch to plug into the Garmin display or the joystick control. An interesting tidbit: CPAC Systems, a subsidiary of Volvo Penta, designed both the Volvo Penta joystick control systems and the Helm Master system for Yamaha, so that knowledge base was applied to a control system specific to Seven Marine.

Tiara says the Seven 527 package will be a regular option for the Tiara Sport 38 LS, but it has no immediate plan to offer Seven outboards for its other Sport models.

Like other models in the Tiara Sport series, the 38 LS, which was introduced in 2017, was designed specifically for outboard power. Until the introduction of the Seven
Marine package for the 38 LS, Tiara Sport models have been offered exclusively with Yamaha outboards. (That brand is offered on the 38 LS, too, including triple Yamaha F350s with a base price of $517,900.) However, Tiara also has a long relationship with Volvo Penta, having first installed a prototype of its IPS pod drive in the 3800 Open in 2005.

The DuoProp gearcase adapted to the Seven Marine outboard on the latest iteration of the 38 LS is the DPH model, originally designed to handle the torque of diesel engines and well suited to the 1,150 foot-pounds of prop-shaft torque the Seven Marine 527 can produce. That torque is transferred to the water through a pair of 18-inch-diameter props.

“Our DuoProp technology delivers the largest propeller blade area in the industry, so when you combine that with the high horsepower rating of Seven’s outboards, it creates the ability to push larger and heavier boats more efficiently, no matter the speed,” Huibers told Soundings. “Increased fuel efficiency is a big perk, but the package also enables easier maneuverability at lower speeds.”

The Seven Marine package on the Tiara includes a suite of Volvo Penta Electronic Vessel Control features at the helm, such as joystick and glass cockpit.

The Seven Marine package on the Tiara includes a suite of Volvo Penta Electronic Vessel Control features at the helm, such as joystick and glass cockpit.

According to Tiara, the top speed of the Sport 38 LS with the Yamaha or Seven Marine engine options is almost the same, at 47.8 knots for the twin Seven Marine 527 rig and 48.3 knots for the triple Yamaha F350s that are also offered with the boat.

“However, the Seven-powered boat is faster to plane and able to hold plane at a lower speed,” says Tiara spokesperson Whitney Vishey, “and delivers better fuel economy at cruising speed, .93 mpg compared to .85 mpg for the Yamaha-powered boat.”

Before the end of this year, Volvo Penta plans to offer its DuoProp gearcase and EVC features with the Seven Marine 527s and 627sv models. Time will tell if the Volvo Penta/Seven Marine marriage gains traction, and whether Mercury and Yamaha, the big dogs in the outboard market, will mount a challenge with models rated for more than 500 hp.

It’s clear, however, that outboard power is ascendant. Somewhere, Ole Evinrude is probably smiling. 

This article originally appeared in the June 2019 issue.