Goin’ Deep

Posted: June 1, 2013

Is there an electric outboard in your future?

By: Alan Jones

Sounding rather like the name of a rock band or the source of clandestine information, Deep Blue is actually the new leader of the pack in electric outboard power, producing a whopping 80 hp, which is enough to get small boats on plane and moving at a fast clip. Most of us are familiar with electric outboards only as trolling motors for bass boats, and this is sort of like one of those … on steroids. Since 2005, Torqeedo, from Starnberg, Germany, has made its reputation by producing innovative, out-of-the-box electric power solutions for a variety of watercraft — both auxiliary and primary power. But never have its designers come up with anything like Deep Blue. Previously, its most powerful engine produced thrust equal to that of a 15 hp outboard. Obviously, Torqeedo is seeking an entirely new market, and an 80 hp outboard is probably just the start of a new generation of electric outboards.

Not Your Standard Delco
Most traditional electric motors use two or three standard deep-cycle batteries, which can handle the cycle of charge/deplete/charge/deplete for a few years of moderate use without premature aging. But Torqeedo has never gone conventional when it comes to powering its electrics. Instead, it chooses to employ high-tech lithium-based batteries, because of their lighter weight, compact size, lack of memory and high resistance to collapse due to frequent cycling. And the batteries used in the Deep Blue system don’t deviate from this philosophy, with a lithium-ion power source derived from the hybrid auto industry, which makes sense. For this project, Torqeedo teamed up with Johnson Controls, a Milwaukee, Wis.-based company that makes the power supply for the Mercedes Benz E-Class and S-Class electric vehicles. (Germans apparently love this company, but then again it could be the ready availability of bratwurst.)

The energy supply for Deep Blue is a scalable bank of batteries. Each battery produces 345 volts (slightly more than the 12v model on your boat) with a charge of 40 Ah (ampere-hours) and a capacity of 13 kwh (kilowatt hours). To get an idea of their power, a 1 kwh-capacity battery could run a 1,000-watt space heater for one hour. To get any meaningful time on the water in a medium-sized boat, you’ll need three batteries, which is a total system weight of 1,327 pounds. By comparison, a MerCruiser 7.4L V-8 weighs 1,162 pounds. Running time depends on what speed you select, since battery consumption goes up exponentially. With three battery packs at minimum throttle, you have about 13 hours of running time. At half throttle, you have slightly more than two hours. Jam the control wide open, and your running time drops to 42 minutes.

On the Water
Deep Blue made its debut at this year’s Miami Boat Show and was awarded a coveted National Marine Manufacturers Association Innovation Award, judged by members of Boating Writers International. I got a chance to run one mounted on a Zodiac SRM 650 inflatable boat that weighs 1,474 pounds and has a passenger capacity of five, in theory anyway, since the battery packs took up a lot of its cockpit space.

Shoving off from the docks, we mostly heard the slap of waves on the PVC tubes, as expected. But if you advance the throttle just a bit, you hear a noise that sounds like the whine of a giant mosquito, which is especially noticeable at wide-open throttle. This turns out to be the sound of the gears in the lower unit. Weird, you think? The sound is present on gas-powered outboards but is masked by the sound of the combustion engine.

Instead of conventional hexaferrite magnets, Torqeedo uses rare-earth magnets, which are more expensive but result in six times higher field strength, which translates to six times more torque. Unlike combustion engines, electrics produce maximum torque at all speeds, so they are ideal for pushing heavy loads. This is a no-brush design, relying instead on electronic circuits to generate its electric field, so there’s no maintenance required.

Throttle response is instantaneous, which got the Zodiac on plane in 4 seconds. Top speed was a peppy 28 mph. We could back off the throttle to about half and still remain on plane, while conserving battery power. There’s a 5.7-inch screen display that comes with the system, providing detailed information about battery status, and it has a built-in GPS, so you get a precise reading of how far you can go — the chance of getting stranded is minimized.

Wallet Drain
Before you get too excited about the prospects of strapping one of these to your pontoon boat, get ready for a severe zap of electric sticker shock. The engine itself retails for around $20,000, which is high, but then again, a Honda 90 has an MSRP of $11,482. You also need a battery bank, however, and to get any meaningful operating time, you need three batteries, which cost a whopping $49,497. Torqeedo calls this “flat fee” boating, meaning you are essentially paying for your propulsion costs up front. The electricity to charge these batteries costs only $3.62, so if you spend more than $6,000 a year on fuel, it’s just about a financial wash. Of course, that’s predicated on using the boat 150 to 200 days a year. The batteries will retain 80 percent of their charging capability for nine years.

Torqeedo doesn’t pretend its latest product is something for the recreational boater … yet. While Deep Blue is being marketed to commercial interests with specific needs or wealthy consumers on restricted lakes, a look at the explosion of electric-powered automobiles leads me to think an electric outboard could become commonplace. They say that necessity is the mother of invention, and the commercial popularity of hybrid and electric cars indicates we are overdue for a breakthrough in battery technology. Or at the very least, economies of scale will bring the costs down to a more viable level. And when that happens, Torqeedo will be there with an outboard to power your boat.

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