A Thrill Ride I Will Never Forget — Evoy Electric Boats

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The sun rises as the small aircraft hits the frozen ground on the small island of Florø on the Norwegian west coast. My first guess was that the name meant “flowery island,” but it is actually derived from the name “Flora” which might originate from the word “Flóð” which means “Strong current,” somewhat appropriate in regard to high power electric boats. Florø is the furthest western located city in Norway, and is about as far north as Anchorage, Alaska.

This December, a couple of inches of snow covers this fairytale landscape, and I’m thinking to myself that this corner of the world will be on my list of the most beautiful places I have ever seen. I finally get what the planet builder Slartibartfast in The Hitchhiker’s Guide To The Galaxy meant when he said: “Did you ever go to a place… I think it was called Norway? … That was one of mine. Won an award, you know. Lovely crinkly edges.”

Crinkly indeed, and today a clear blue sky and no wind make the ocean stretching into the fjords look mirror-like. Evoy CCO Marte Rostrup Hofset has been accompanying me from Oslo where she works out of Evoy’s office in the capital city. Every once in a while she makes the one hour flight to the Evoy factory, and today she is my guide.

Big Vision In Humble Setting

Evoy is an electric marine propulsion startup founded in 2018 by CEO Leif A. Stavøstrand, who welcomes us at the factory. “I was the CEO of Norway’s largest oil and gas supply base, but I felt that I had to move on and try to get away from the primary fossil fuel industry. I love boats, and I found a way to make my passion my living, through the electric propulsion technology of the future!”

Now, 4 years later, it is clear that Leif’s vision is coming into fruition. Evoy is the workplace for 43 highly skilled people in the maritime business. A tightly specified line of products reveal themselves on the factory floor. Some systems are going out as regular orders to boat builders around the world who install them effortlessly into their products, other systems are more complex and Evoy will assist with final assembly at the customers site, while yet some systems are still in the prototype stage.

Roughly speaking there are two types of systems in Evoy’s lineup: inboard and outboard. Battery packs are always inboard, though. As we walk around the factory floor, COO Åge Højmark and production manager Taimoor Arif explain the details about the systems, the working progress, and the strategy of deployment. It’s the small things that matter when your aim is to scale up into a global market.

“Take the connectors, for example,” Mr. Arif says, “we put a lot of effort into making sure the systems are robust as well as plug and play, and that they cannot be assembled the wrong way, so a lot of thought goes into the shape, function, and ruggedness of the many connectors needed.”

It’s fascinating to see the builds and test benches on the factory floor. Everything is put together from the ground up, and there are full-boat setups to test and specify the various installation requirements in regard to positioning and balance of certain types of hull, and there are stand-alone system tests, like a dual motor outboard system where the synchronization of two normally independent systems is setup via software to work effortlessly and to the customers requirements. “We are at a point of scaling up significantly,” says Mr. Højmark, “and we are ready to assemble and deliver a lot of systems in the coming years.”

Pricing depends on how much the boat builders do themselves, but according to Evoy’s online configurator, a rough price range across all system configurations is €85,000 to €340,000 ($90,000 to $360,000). And as an example of a finished boat you can buy right now, the Hydrolift E-22 is available in Norway at a price beginning at €133,000 ($142,000).

Thrill Ride

The snows squeaks under our feet on the boardwalk in the Florø harbor since the temperature has only gone up from about -10 degrees C to a warmer -8 C (18 F). Two boats await us: The rigid hulled inflatable type Goldfish X9 Explorer with a 400+ horsepower (peak 800) inboard system called Hurricane, and the regular V-shaped hull type Axopar with a 300+ horsepower outboard prototype system called Storm. The idea is to go in both boats and switch halfway to get a sense of the different types of hull and propulsion systems. I start in the X9.

Usually I’m not at all happy about freezing temperatures, but in this scenario, with the anticipation building of what’s coming, and the fact I’m wearing a survival suit as well as genuine Norwegian socks — I’m boiling inside. We head out to get some room around us, and after enjoying the unbelievable scenery around us for a few minutes, eventually the question arises from Mr. Stavøstrand: “Would you like to try?”

I mean, I’ve experienced electric propulsion systems in cars for many years, and a few hundred kW of instant power has not shaken my stance lately, but I was not prepared for this. So quiet and civilized at low speeds, but when you push that throttle…

Maybe it’s the unfamiliar sound of gears and propellers, maybe it’s the unfamiliar buildup of speed, accompanied with the lack of stationary reference points around you. The word exhilarating does not do the sensation justice, because it was absolutely insane!

First of all, you’re standing up straight! And second, you can only have one hand on the wheel, because you need to have your other hand on the throttle at all times. This means your stance is kind of bad-ass-bring-it-on whether you’re that type or not. And while you stand straight and hold on to about two metric tonnes of machinery leaping forward like a cheetah, the whole thing tilts backward lowering the rear and rising the front. A couple of clicks on a button on the throttle tilts the counter rotating dual propeller sterndrive downward to maintain traction.

In what seems like no time at all, the X9 reaches over 50 knots (60 mph/90 km/h) and a glance at the power meter shows 410 kW! That’s 550 horses kicking up water! It is very cold and the battery has not reached optimal working temperature yet allowing for the last 250 horses to be let loose (totaling 600 kW). Honestly, at this point I should have been a little intimidated and probably not willing to have my face whipped cold with icy water for longer, but contrary to my anticipation I wanted more!

Some rather bulgy bow waves from a cargo ship that passed a few minutes earlier were closing in and instead of slowing down, something convinced me that this machine was built for the rough, and without hesitation, and no objection from Leif standing next to me, I held the X9 on course, planing at its best, as we hammered through the bow waves making a few jumps, big enough to make my guide Marte shout that she lost her hat!

Next up was the Axopar. For leisure, this is the way to go. Later in Oslo I would be trying a smaller boat with a 120 horsepower displacement, but this one has a 300+ horsepower prototype outboard, with the same long range battery as the X9. The long range twin module battery configurations on the X9 and Axopar makes 800 Volt propulsion possible and is key to the outstanding performance achievements. The peak performance of this outboard system, appropriately called Storm, has not been determined yet, since it is still being validated.

The gearing in the Axopar is a traditional outboard setup with mechanical reverse. Evoy does not build the transmissions in-house, but utilizes the well proven lower leg systems available. Thus the electric motor is set to only be able to run in one direction, and use the mechanical reverse while obviously capping the power output. When manufacturers eventually do provide gearing made for electric propulsion, Evoy will shift to that and simply reprogram the control software to make the motor run backwards when reversing.

In any case, this outboard system seems much quieter than the inboard. It still makes a roar at full power, but having only a single rotating propeller as opposed to the X9, it is dead quiet at speeds below 7 knots (8 mph/13 kph). Perfect for fishing and tourism in the wild. Don’t let the elegant exterior fool you, though. The powerhouse bolted to the rear of this hull throws a serious punch, and just like the X9, you have to hold on tight when pushing the throttle. What a blast! Surpassing 45 knots and 300 kW (400 HP) of power output, it’s clear that this thing has more to give, but frankly, I think my eye sockets were freezing up and the responsible thing to do was to hand the beast back over to Leif.

Night Ride

Back on shore, I had a few questions about the technical specifics answered by CTO Marius Dyrseth, and as he gave me a ride to the airport it was clear it would be dark before I reached Oslo. I was to meet up with sales manager Thomas Mordt Kolstad, who would demonstrate the smaller 120 horsepower outboard system called Breeze.

Downtown Oslo that evening was virtually a winter wonderland. The temperature was back down to -10 degrees C (14 F), and snow was falling gently, no wind at all. The harbor area was packed with people, and all you could hear was chattering and the squeaks from walking in fresh snow. Out on the water, electric ferries came and went in complete silence. It was a dream-like scenery.

Mr. Kolstad welcomed me onboard the sleek Hydrolift E-22 parked at the electric-vessel-only dock, and we headed out into the darkness. This outboard system is also dead quiet at low speeds, but even though it is under half the power of the Axopar’s Storm system, it was amply capable of getting a move on. Getting above planing speed which occurs around 18 knots (21 mph/33 kph) almost feels like a single jump forward.

Blasting forward into the darkness reaching 35 knots and passing a ferry, I asked Thomas if he knew where he was going? He assured me not to worry, and asked me to take over. My courage lasted for about 10 seconds. Total darkness and snow wiping into my eyes. Fun is such a small word!

We turned around and glided back to the dock among ferries and Norwegians in floating saunas (yes!) with the most amazing December holiday lighting as the backdrop, I had to pinch myself…

Boat Dynamics

It takes some getting used to when thinking about range in an electric boat. Power consumption related to speed in a boat is not at all as intuitive as with cars. When driving a car, you have a little bit of rolling resistance, but the joker is wind resistance on the forward facing surface, which rises to the square of the speed. It’s pretty easy to conserve power in a car: just slow down.

However, on a boat you have a phenomenon called hull speed or displacement speed which is the speed at which the wavelength of a vessel’s bow wave is equal to the waterline length of the vessel. As boat speed increases from a standstill, the wavelength of the bow wave and height of the crest-to-trough increases, thus at hull speed you are essentially riding uphill on the tail of that crest of the bow wave, which is very inefficient. Increasing power hardly increases speed, it just makes the bow wave bigger.

To increase efficiency you have a choice, either you stay way below hull speed or start planing, i.e. increase the speed to the point where the hull starts skipping on the water over the top of the bow wave as opposed to plunging into it, thus moving the bow wave backward and decreasing its crest-to-trough height to minimize its influence. This is only possible with a hull designed for planing: the flatter the bottom of the hull, the easier it can do planing. Like skipping stones on a lake: a flat stone skips, a round stone doesn’t.

I observed that going 11 knots in the Axopar consumed a continuous 45 kW, but when easing off to 5 knots it declined to 14 kW. Very little energy is used below hull speed, thus decreasing the speed to 1 knot only consumes 1 kW. Go slow for exceptional range, or go fast if you don’t have all day. The Axopar is 25 feet long (7.6 meters), and its hull speed is calculated as 1.34 knots x 25 feet squared = 6.7 knots (probably a bit lower since its waterline is somewhat less than 25 feet). Above the hull speed, energy consumption rises dramatically, until the point of planing.

Now, you may be thinking that all this seemingly excess power is senseless, and carrying all those heavy batteries is pointless, and in a narrow use case scenario you would be right, but power is not just fun, it’s essential in a whole range of maritime applications. Think tour operators, aquaculture, offshore services like energy and coast guard, rescue vessels, and even small ferries. The same system can do high speed transport with a small flat hull vessel, as well as low speed hauling with a big bulge hull vessel.

I showed the graph above to Leif and he comments:

“We often refer to hull speed to guide our stakeholders and customers what speed to use. With electric boats it becomes very evident as you get an immediate and accurate feedback on consumption per distance sailed. The 6 — 18 knots band as you mention is a no-go as you can use 3 times the energy in 10 — 12 knots than at 5 or 25 knots. So the hump you show from 6 — 18 knots is actually significant higher on a plane hull boat.”

Leif explains further that the very precise consumption readouts make it a lot easier to optimize trim, and weight distribution, as well as observe precise water current directions in a fjord or harbor. For example, when Leif travels to his parents’ place he can have below 4 kWh/nm (nautical mile) one way and over 5 kWh/nm the other way on the same route within the same hour. And that is on a wide and open fjord, so it is surprising how much the current affects the range. To a certain degree, even more than the wind.

To summarize: Energy consumption with electric boats is even more complicated to estimate than with electric cars. Kudos to Evoy for making a user interface so easy to read and understand, and deem range anxiety a non-issue. With the wide dynamic range of power from electric systems in general, you don’t need as many different sizes of displacement. Take the Hurricane inboard system as an example and imagine a dual system on a small ferry at low speed with a more adequate usable range. Evoy want to cover as many applications as possible with as few systems as possible in order to scale up effectively.

Power Electronics

Over the last 4 to 6 decades the development of power electronics has made it possible to control ever more power electronically. Merging electrical machines such as motors and generators with still faster electronic inverters at a still lower price, has allowed a large range of new alternative ways to convert power back and forth between electrical, mechanical (rotational), and thermal energy.

Evoy has chosen SiC MOSFET (Silicon Carbide Metal Oxide Semiconductor Field Effect Transistor) in its DC/DC conversion electronics, and Si IGBT (Silicon Insulated Gate Bipolar Transistor) in the inverter that produces AC current for the motor. Which kinds of power semiconductor technologies are used by electric drivetrain manufacturers have changed over the years. They all have their pros and cons.

To the consumers, the key concern should be whether the mechanical and thermal design has been done meticulously and all available data for all the components have been scrutinized. Generally, it is more or less impossible to obtain a reliable confirmation of these and related questions. However, relentless real world testing as well as intentional rugged engineered of the thermal management of all parts of the system, will ensure reliable high power operation under extreme weather conditions in all parts of the world.

Oh, and it should be mentioned that, like with cars, the difference of power delivery between an electric drivetrain and a traditional fueled drivetrain in terms of rpm and torque makes it feasible to look at other things like the physical design of hulls and propellers. Let’s just say I saw things on the factory floor that I did not expect to see.

Controls

Evoy software can monitor a system installed in a vessel 24/7 and deploy Over-The-Air (OTA) software updates. This keeps systems in daily use up to date and provide easier remote diagnostics and maintenance. Nextfour in Finland provides the screens onboard in various sizes, and with single or dual screen options.

Evoy’s control system is called E-Brain, as a hint to the company’s realization that this element of software prowess is crucial for their success. Evoy has developed their own app for user convenience. This is no different from electric cars, where the fundamental software architecture has to work seamlessly in order to keep the customer happy.

Charging

Of course there is a challenge when it comes to charging, and from what I’ve seen in Norway it’s obvious you have to prioritize dock chargers, which they certainly do!

I can imagine solar installations be viable in this regard, especially on small uninhabited islands. Boats might be in dock longer than cars are in parking lots, so some extent of local power generation will make sense. As lightweight foldable solar cells scale up, maybe those could be rolled out on the water to provide real offshore charging. It certainly makes more sense than transporting fossil fuels around. Still, winter darkness is obviously a challenge.

Starting in 2023, a Swedish-Norwegian joint project will establish over 400 charging stations along the Swedish and Norwegian coastlines. Spanning from Göteborg to Strömstad in Sweden and continuing along the Norwegian coast line from Oslo to Kristiansand, the charging infrastructure will be the first of its kind in Europe.

And of course cars and boats can share chargers if physically installed to reach both:

From Here On

As I mentioned, Evoy is focusing on scaling big globally relatively fast and the means to do so effectively is to concentrate on few and modular systems. The right amount of motor configurations in various power ranges combined with a streamlined, modular, and rugged approach to battery packs will result in a lot of different options that will fit a huge range of boat sizes and types. Motors and control systems will continue improving due to ever increasing prototype testing and OTA feedback from real world applications, and on top of that there is the benefit of the fact that battery technology just keeps getting better, lighter, and cheaper. That’s true for all transportation industries, and what benefits, say, electric cars, will obviously also benefit electric vessels. Weight and ruggedness are key factors here.

The future of electric transport is really exciting, and though I have been focusing on cars for now, I am very happy to discover that the world of marine transport is going to be no less exhilarating! I remember driving an electric car for the first time in 2011 and thinking: I want one! Now, I will never forget my first ride on a powerful electric boat, because my first thought was: I want one!

The Boats

From the Evoy website:

Evoy means “Electric Voyage.” A voyage is by definition “a long journey involving travel by sea or in space.” For Evoy, this means sea travel. At least for now.

Goldfish X9 Explorer:

• Length: 31 feet (9.7 meters)
• Hull total displacement: 2 tonnes (4410 lb)
• Top speed: 60+ knots
• Range at 32 knots (plane above hull speed): Approx. 48 minutes/26 nm
• Range 5 knots (below hull speed): Approx. 12 hours/60 nm

Propulsion system: Evoy Hurricane inboard (available now)

• Motor type: Liquid cooled 3-phase AC PM
• Motor weight: 220 kg (485 lb)
• System weight excl. battery: 300 kg (661 lb)
• Motor power output nom. 400 HP (300 kW) — peak 800 HP (600 kW)
• Motor torque: nom. 770 Nm — peak 1500 Nm
• Motor RPM: nom. 3750 — peak 6000
• Drivetrain type: Sterndrive gear ratio 1:87 dual contra-rotating propellers
• Waterproof: IP 66
• Controller: E-Brain proprietary design by Evoy with OTA updates & diagnostics
• Inverter: Si IGBT
• DC/DC: SiC MOSFET
• Power: 365 VDC x 2 = 730 V at peak 1000+ A

Battery:

• Cell type: NMC
• Pack weight: 760 kg (1675 lb)
• System weight excl. motor system: 780 kg (1719 lb)
• Pack capacity: 126 kWh (112 kWh usable)
• Waterproof: IP 67
• Discharge/charge: 2C/1C (1000/500 A)
• Charging cycles: 3000 with 70% DOD

Charger:

• AC: 22 kW (44 kW option)
• DC: up to 200 kW

Axopar:

• Length: 25 feet (7.6 meters)
• Hull total weight: 1.8 tonnes (3970 lb)
• Top speed: 45+ knots
• Range at 25 knots (plane above hull speed): Approx. 1 hour/25 nm
• Range 5 knots (below hull speed): Approx. 14 hours/70 nm

Propulsion system: Storm outboard (available 2023)

• Motor type: Liquid cooled 3-phase AC PM
• Motor weight: 270 kg (595 lb)
• System weight excl. battery (outboard + inboard parts): 350 kg (772 lb)
• Motor power output nom. 300 HP (222 kW) (Peak not verified)
• Motor torque: nom. 550 Nm (Peak not verified)
• Motor RPM: nom. 4200 — max 6000
• Drivetrain type: one leg gear ratio 1:87 with mechanical reverse
• Waterproof: IP 66
• Controller: E-Brain proprietary design by Evoy with OTA updates & diagnostics
• Inverter: Si IGBT
• DC/DC: SiC MOSFET
• Power: 365 VDC x 2 = 730 V at peak 1000+ A

Battery:

• Cell type: NMC
• Pack weight: 760 kg (1675 lb)
• System weight excl. motor system: 780 kg (1719 lb)
• Pack capacity: 126 kWh (112 kWh usable)
• Waterproof: IP 67
• Discharge/charge: Nom. 2C/1C (1000/500 A) Peak 4C/-
• Charging cycles: 3000 with 70% DOD

Charger:

• AC: 22 kW (44 kW option)
• DC: up to 200 kW

Hydrolift E-22

• Length: 25 feet (6.7 meters)
• Hull total weight: 1500 kg
• Top speed: 35 knots
• Range at 20 knots (plane above hull speed): Approx. 1 hour/20 nm
• Range 5 knots (below hull speed): Approx. 7 hours/35 nm

Propulsion system: Breeze outboard (available now)

• Motor type: Liquid cooled 3-phase AC PM
• Motor weight: 190 kg (418 lb)
• System weight excl. battery (outboard + inboard parts): 250 kg (550 lb)
• Motor power output nom. 120 HP (90 kW) — peak 185 HP (137 kW)
• Motor torque: nom. 170 Nm — peak 270 Nm
• Motor RPM: Nom. 4900 — peak 6000
• Drivetrain type: one leg gear ratio 1:87 with mechanical reverse
• Waterproof: IP 66
• Controller: E-Brain proprietary design by Evoy with OTA updates & diagnostics
• Inverter: Si IGBT
• DC/DC: SiC MOSFET
• Power: 365 VDC at peak 500+ A

Battery:

• Cell type: NMC
• Pack weight: 380 kg (837 lb)
• System weight excl. motor system: 400 kg (881 lb)
• Pack capacity: 63 kWh (56 kWh usable)
• Waterproof: IP 67
• Discharge/charge: Nom. 2C/1C (1000/500 A) Peak 4C/2C
• Charging cycles: 3000 with 70% DOD

Charger:

• AC: 6.6 kW (option 22 kW)
• DC: up to 200 kW

And the sound? Turn up the volume…

Hat tip to my friend engineer Steen Carlsen M.Sc. E.E. for his help on the power electronics part.

Disclaimer: Evoy paid for the flights, one night at a hotel, and a sandwich. Other than that I paid for fares and food myself. I did not receive any kind of gifts.