Skip to main content

The Future of Electric Marine Engines

What’s the next step in marine propulsion?
 We visit a boat show on an “all-electric” German lake to find out.


As I ambled out of the Vier Jahreszeiten hotel in Starnberg, Germany, a young guy stood next to a little BMW i3. His hand was on the front door handle, there was a broad grin on his face and a big orange Torqeedo logo embellished the car’s rear door. Torqeedo, of course, is the upstart German company whose name these days is synonymous with waterborne E-Mobility around the world.

I jumped into the passenger seat. I’m no stranger to hybrid-electric vehicles but this was my first fully-electric car. And we were looking at a long haul, my driver explained. Torqeedo’s manufacturing facilities were located in the hinterlands of Bavaria.

“But don’t worry, sir,” he added, “we shall go quite swiftly.”

As the roadside evergreens began whizzing past, I eased back in my seat to take stock. The day ahead was the centerpiece of Torqeedo’s “Electric Days” celebration, an annual event featuring a dozen or so journalists and a veritable fleet of electric boats. The festivities would begin with a tour of the facilities we were zooming towards. Then, after returning to Starnberg and lunch at the Munich Yacht Club on Lake Starnberg, an afternoon of sea trials would follow, some energized by the very same BMW lithium-ion battery currently juicing the little i3.

“What’s that number?” I asked, pointing at the display within the instrument cluster. “Our range?”

“Yah” the youngster affirmed, with a sideways glance. “We are not quite full-charge. So, at present, 190 kilometers is our range. Which is, I think, around 120 miles, as you say in the States. Would you like to drive the car for some while?”

He didn’t have to ask twice. We pulled over and swapped places. Then, after I’d signed a form, essentially declaring that I’d pony up outrageous bucks if I destroyed one of Torqeedo’s brand-new shuttle cars, I settled in, buckled up, gripped the steering wheel with gusto and nudged the i3 back onto the road. After a few kilometers of polite acclimation, my freewheeling companion suggested we pull over again.

Lithium-based batteries are tested at the Torqeedo facility prior to shipping.

Lithium-based batteries are tested at the Torqeedo facility prior to shipping.

“Wait here until the traffic clears,” he said, “then go full force.”

Although I was quite aware at the time of the buzz concerning full-electric acceleration—electric motors produce lots of torque fast, at least by comparison with combustion engines—the pickup the i3 evinced when I, as they say, punched it, was a total jaw-dropper. I couldn’t believe it. The speedo hit 100 kilometers (60 mph) in what seemed like about three New York seconds flat!

“Whoooeeeee,” I yelled, backing off. “That is fun, buddy!”

Industrial-Strength Voltage

Over the years, I’ve written stories for Power & Motoryacht about E-Mobility and its application to marine propulsion. But most of these pieces have involved low-voltage or largely theoretical applications, so when I arrived at Torqeedo that morning, I somehow retained the notion that creating a big-time, fully-electric marine propulsion system entails little more than installing an electric motor, a bunch of batteries and a controller or two. My plant tour soon relieved me of this naïvete, especially as it pertained to high-voltage safety.

While escorting our platoon of journalists through an array of spotless offices, laboratories and work rooms, Dr. Christoph Ballin, Torqeedo’s CEO, stopped at one point to detail the intricacies of the company’s new-for-2019, 40 kWh Deep Blue lithium-ion battery, the company’s version of the same powerful battery that had just enlivened my i3 driving experience.

As I listened, it eventually dawned on me: Yikes, this guy is talking about a 360-volt-capacity system here—industrial-strength electricity! Installed on a boat. Which typically floats in a highly-conductive substance—water! Sure, his company’s safety record is solid, barring some recent battery-housing issues with smaller, lower-capacity lithium-ion products! But hey, 360 volts?


“We have partnered with BMW on the 40 kWh project,” Ballin said, nodding toward the Deep Blue on display, “because we believe BMW offers the best and safest high-capacity solution on the market today.”

Ballin then listed a raft of impressive features Torqeedo adds to marinize the i3 battery. Highlights included attaching a rugged, all-encompassing aluminum frame with suspension mounts to the existing damping mechanism; surrounding all components with extra insulation to obviate shock; routing an emergency exhaust system (with waterproof port) to safely vent hot gases overboard in the unlikely event of an interior cell failure; fitting a thick, rubber IP67-certified waterproofing gasket inside the battery’s case; incorporating an automatic shutdown mechanism should an electrical fault be detected; and modifying BMW’s Battery Management System software to mitigate the necessity for harmful, automotive-centric discharge-rate extremes.

“The BMW battery is certified to automotive standards,” Ballin concluded before moving on with the rest of the tour, “but we expect to have Det Norske Veritas/Germanischer Lloyd certification by the end of 2019, at least for the commercial and life-saving versions of the product. Such certifications, of course, mean we will then have highly reliable marine standards as well.”

Torque, Torque and More Torque

I was a little disappointed in the Frauscher 740 Mirage Air, the first boat I sea trialed that afternoon. Not that the 24-foot speedster wasn’t a sleek beauty. But then again, shortly after I’d throttled up on the lake, I knew something was fishy in Bavaria.

“You’ve got some serious vibration here,” I observed to Florian Helmberger, Frauscher’s head of marketing.

The Frauscher 740 is available with conventional inboard combustion power or with an all-electric system. 

The Frauscher 740 is available with conventional inboard combustion power or with an all-electric system. 

Both Helmberger and I were crestfallen. The 740, with a pair of Ballin’s much touted Deep Blue 40 kWh batteries on board, was the only watercraft at the event to showcase Torqeedo’s latest and greatest motor, the new 100-kW (134-hp) 100i. And I’d certainly been looking forward to the top hop Frauscher was claiming—26 knots. Fast for a single-engine inboard, electric or not.

“We perhaps have a propeller issue,” said Helmberger, as we made our way back to the marina.

My second sea trial went more smoothly. The Designboats Tender O8 was a lightweight, fully-infused 26-foot inboard megayacht sidekick built in Switzerland, with twin 60-kW Deep Blue 50i motors (80-hp apiece) and two 31-kW Deep Blue batteries (progenitors of the new 40 kWh battery), one stacked atop the other. Before operating the vessel on the lake, I gave her a dockside once-over with Designboats owner Peter Minder.

The Tender seemed conventional at first, with the usual suspects at the helm (Garmin GPSmap 7410 MFD, sport steering wheel and binnacle-type engine control), an Aquadrive system spliced into each straight-shaft drive train and crisp, teak-laid decks. But as I continued my dockside examination, checking out the batteries (in the engine compartment), motors (under the after deck) and controllers (inside the center console), two foreign-looking shore power plugs eventually captured my attention.

“We are charging at the 380-volt rate,” Minder explained when I pointed at the plugs, one on either side of the battery/engine compartment. “This boat handles all voltages automatically—you simply attach the cord from whatever source is available. And you can use both plugs at the same time.”

Minder further explained that from zero charge, a 380-volt source could top off the boat’s battery pack in approximately six hours. He added that topping off with two 230-volt sources would take more time—eight hours approximately—and the time to charge via a combination of the two voltages would fall somewhere in between.

The 7Even from Marcus Glas is an electric runabout.

The 7Even from Marcus Glas is an electric runabout.

I was surprised by the sea trial itself. Here apparently was a genuine, bluewater watercraft that exhibited real high-performance handling. Top speed was 26 knots, the cornering was tight, flat and speedsterish and the acceleration—well, time to plane, at just 4 seconds, reminded me of punching it in the fully-electric BMW.

“Your speed now,” suggested Minder as we zipped across a smooth Lake Starnberg at wide-open throttle, “is limited to about 50 minutes and 20 miles or so. A slower pace of eight miles per hour will give us 10 hours maybe and about 70 miles of range. The display will make you aware of all this and give you an alarm if it is necessary to slow to displacement speeds to get home.”

My final sea trial of the day, the ZenPro 580, was even more impressive than the Tender. She was a tough little 20-foot patrol-type RIB with an aluminum hull, Hypalon tubes and, in lieu of fuel tanks and a combustion engine, a 50-kW (80-hp) Deep Blue 50 R outboard with a 40-kW Deep Blue battery under an after-deck hatch. And unlike the vessels I’d driven earlier, she’d been expressly built for electric power by French manufacturer Naviwatt, according to the Naviwatt rep on board, Berenger Laurent.


But the acceleration! When I firewalled the throttles, the boat launched a veritable G-force festival. Time to plane—5 seconds, maybe a tad more. Quick for an 80-hp motor? That’s not the half of it.

While this phenomenon, as well as the ZenPro’s top speed of 25 knots, were directly related to the instantaneous torque that characterizes electric motors, I soon discovered that dockside maneuvering was in for improvement as well.

“No, no,” yelled one of the shoreside organizers, pointing off into the distance. “Please go there where there is a more correct shore power.”

Since I’d driven the ZenPro almost all the way into the Munich Yacht Club’s marina at this point, the request meant I had to back the boat straight out a considerable distance, rotate her into an adjoining fairway and then go hunting for a parking spot. Although inconvenient, the exercise taught me three things about electric-outboard boat handling.

First, when maximum torque is instantly available at low-end RPM, backdown tracking is seriously enhanced—by comparison with an internal-combustion outboard that needs to gather way for effect, an electric outboard steers in reverse like a pickup truck in four-wheel drive. Second, there’s no lag time when shifting an electric outboard’s engine control from forward to reverse—gone is the neutral detent and the wasted seconds. And third, handling is generally more relaxed and precise with an electric outboard—prop speeds can be slowed to a crawl if necessary or instantly boosted.


Green Lakes of Germany

It was late afternoon and the “Electric Days” celebration was at a close. I sat at an umbrella-shaded table on the patio of the Munich Yacht Club thinking about all the people I’d talked to during the day. Certainly, there’d been consensus on a number of things. Everyone had agreed, for example, that E-Mobility is at least a partial answer to the perils of climate change. And there was general agreement that battery technology is increasingly sophisticated. But there’d been a few comments that were less straightforward, less positive.

Norbert Geissler, a long-time Munich Yacht Club member: “We are beside one of Germany’s so-called green lakes, a pollution-free, all-electric lake if you will. So, excluding the boats used for our sailing regattas on Lake Starnberg, we have only 265 licenses here for petrol power for this huge body of water. And there is a 20-year waiting list.”

Peter Minder, Designboats owner: “What’s happening now in Germany is driven by government regulation. If you admit, as I think you must, that most politicians today want to have a green agenda, or at least appear to have a green agenda, a certain dynamic is created. In Germany, for instance, there are much fewer owners of boats compared to owners of cars (which are the largest polluters by far) so the politicians will move against the weakest, smallest segment of the population, the boaters, to get their green agenda. Not the car owners.


“Then there is Austria to consider. Almost all the lakes in Austria are strictly all-electric except for the Woerthersee, which is a large, beautiful lake mostly for the rich and the famous. Yes, you are still allowed to run a limited number of combustion engines on the Woerthersee, but a license will cost you the equivalent of $280,000 U.S. dollars. And the waiting time—you can’t even believe it.”

So, was there a gloomy side to E-Mobility on the water, I had to ask myself, as I watched an electrified mahogany runabout ghost silently across the lake towards the Alps. Would E-Mobility make boating so expensive, so exclusive and so regulated that the average person could no longer afford a boat?

Frauscher’s Florian Helmberger had given me at least a little hope earlier in the day. “New technology is always expensive in the beginning,” he’d opined. “But then companies like Torqeedo and others create better and better products in higher volume and the costs come down. So electric boats will eventually become quite common and competitive on the water. That’s what I think. And, I presume, they will be increasingly efficient, versatile and affordable for, let us hope, the average person.”


This article originally appeared in the August 2019 issue of Power & Motoryacht magazine.