Nic Compton In designing their electric outboards, the principals at RAD Propulsion started by identifying the most efficient propellers for a given thrust and speed.
It seems inevitable in 2026 that any company with an innovative approach to electric transport will be compared to Tesla. And if that company is involved in marine transport, there’s almost an inevitability it will be referred to as “the Tesla of the seas.” It’s a lazy comparison, yet as I talk to some of the players behind RAD Propulsion at their offices near Southampton on the south coast of England, it repeatedly comes to mind. These are smart, tech-savvy people taking a bold approach in a fast-moving world with massive potential but also huge risk for failure. Sound familiar?
“When we first started this,” says RAD Director and co-founder Rich Daltry, “we looked at the electric outboard market and thought everyone’s taken an internal-combustion format and just whacked an electric motor on top, which is near enough what most people are still doing. And we just didn’t understand why. When you look at a Tesla, apart from where the four wheels are placed, its architecture is almost entirely changed from a combustion-engine car. Why would you just do the same thing again?”
Daltry continues, “We weren’t being devil’s advocates, deliberately doing it a different way. We felt, well, OK, what can you do? What new features can you bring to the market? So, we started with the prop. What’s the most efficient prop we can give for a given thrust and speed? And then we worked our way back up the drivetrain, from the propeller up.”
Courtesy RAD RAD co-founders Dan Hook and Rich Daltry.
The conclusion Daltry and co-founder Dan Hook reached was that there was definite room for improvement—starting with the propeller. Because electric motors produce incredible torque—the capacity to go from zero to maximum power almost instantly—they can swing bigger propellers than a gasoline engine. The 40-kW outboard they were designing could easily cope turn a 13″ (33mm) propeller (and larger) rather than the standard issue 11¼” (286mm) model fitted to an equivalent gas outboard. If correctly pitched, those bigger propellers could increase efficiency.
Another holdover from conventional gas outboards was the cooling system, with water intakes on the leg and an exhaust exiting through the propeller, creating more drag. An electric engine doesn’t heat up as much, so it can be cooled internally by a closed-circuit system fitted with a heat exchanger. Job done. No need for raw-water intakes and the associated complications of blocked filters and corrosion—and you get a more streamlined propeller into the bargain.
Courtesy RAD The RAD electric motor has a distinctive low profile which depends on its ability to be submerged in service. Installation is simplified by the fact that the fixed powerhead doesn’t need room to rotate in steering the boat.
Blue-sky thinking was also needed for the steering system. Daltry and Hook wanted to incorporate 180° rotation, which they achieved by fixing the top part of the outboard (the powerhead) and only rotating the lower leg. After all, why swivel the whole unit when only the lower leg needs to turn? When fitted to the back of a boat, this has the added benefit of freeing up space normally needed to accommodate the arc of the outboard powerhead. In practical terms, that means appendages such as a bathing platform can come right up to or even over the engine.
The next step was to hinge the outboard from the top of its front edge rather than from under the powerhead, so when it was raised it didn’t impinge on the internal space. This effectively frees up almost a cubic meter of internal volume, a significant factor on a 6m (19.7′) RIB, for instance.
For the motor, they opted for an axial-flux geometry rather than the more common radial-flux technology found on most electric outboards. We won’t go deep into the relative merits of axial versus radial here, but suffice to say axial is lighter, more compact, and more energy-efficient—with a claimed efficiency of 96% compared to 80% for a standard brushed motor (or just 35% for an internal-combustion engine). Axial-flux motors are often described as “pancake” designs because they are low, wide, and round.
Alison Langley In place of a central inboard engine in this classically styled 26′ (7.9m) commuter launch from Stephens Waring and Belmont Boatworks in Maine, is the massive 400V battery powering the RAD 40 motor discreetly installed under a shapely curved transom.
The system was designed to be powered by 400V batteries, which deliver greater power and can be rapidly recharged at a suitable fast-charging station. For their first creation, they chose 40 kW (rated at 55-60hp) as a popular mid-range size that could power most RIBs and other small motor vessels.
When the RAD 40 launched in 2022, it looked strikingly different than anything else on the market. The pancake motor configuration means the outboard sits extremely low, with almost none of it protruding above the transom of an average RIB. At first sight, it looks more like a sterndrive than an outboard. Indeed, the whole low-profile engine is submersible and has been tested underwater to a depth of 1m (3.3′)—although it’s not recommended as common operating practice.
The steering and throttle are digitally operated, making installation remarkably simple. There’s no need for elaborate push-pull cables or hydraulic systems. All you have to do is attach the outboard to the transom, connect the power cables to the appropriate batteries, and plug the electronic control cables into the appropriate controls at the helm. And you’re away.
In short, the RAD 40 is efficient, unobtrusive, and aesthetically current and cool. It’s the sort of product you’d be proud to own—like a Tesla in the early years.
Use Profiles
The RAD 40 has proven popular for working boats and defense vessels, increasing numbers of which are unmanned. The work patterns of these vessels are often ideally suited to electric propulsion, as they typically spend all day working—occasionally going fast but mostly at slow speeds—before being docked overnight, when the batteries can be recharged. Daltry estimates the RAD 40 fitted with a 120-kWh battery will run for three hours flat out and much longer at lower speeds, with a range of about 100 miles—ample for many workboat applications. For long-range autonomous craft, the engines are used as part of a hybrid system powered by gas generators and solar panels.
The RAD 40 has also found favor among expedition cruise ships and ecotourism operators. Unlike many electric outboards, the motor on the RAD 40 is located out of the water rather than in an underwater pod, making it much quieter underwater—an advantage for wildlife watching.
“Our customers are commercial operators who work in an environment where you don’t want petrol and diesel noise or the association with pollution,” says Daltry. “It’s primarily noise, if we’re honest. It’s less about CO2 emissions, albeit that’s a factor, too. But it’s actually much more about the experience in nature and wildlife. Their customers are paying to go on very expensive cruises and holidays. And if you’re going nature-watching, you don’t want the sound of a diesel or petrol outboard while you’re trying to watch whatever it is you’ve found out there. So, that’s a big market right now.”
Courtesy RAD Four RAD 40 outboards charged by solar panels power this floating hotel on the Chobe River in Botswana.
There were other, more surprising applications, such as the floating hotel used for wildlife safaris on the Chobe River in Botswana. Four RAD 40 outboards have been fitted to the large trimaran platform, one on each corner, allowing it to move in almost complete silence and get significantly closer to wildlife. Combined with solar panels and a pair of 61-kWh batteries, the propulsion system is completely self-sufficient, delivering a 100% fuel-cost savings.
So far, so good. But Daltry and Hook have bigger ambitions than just making electric outboards. The two former naval architects have a background in maritime robotics, having previously founded a company that built unmanned surface vehicles (USVs)—a company they eventually sold before starting RAD in 2018. The new company’s first major project was developing a rim-drive for RS Electric’s new range of electric RIBs. Better known for their range of high-performance sailing dinghies, RS had decided to expand into the emerging electric motorboat market with its own 20′ RIB. The Pulse 63 featured an innovative cathedral hull, with a deep central section and sponsons (or outriggers) on either side, partly made from recycled water bottles. Although the rim-drive—essentially a propeller mounted inside a spinning cylinder—turned out to be a blind alley, the eventual outcome of that project was the RAD 40, launched in 2022 and fitted to the revamped Pulse 63 the following year.
Courtesy RAD RAD’s background in unmanned systems make the outboards well suited to remote and autonomous operation.
Other partnerships followed, including the Hyrex 28, a zero-emissions day cruiser powered by hydrogen cells; and the Valkama, a 17′ 4″ (5.3m) aluminum speedboat capable of 25 knots. When I visited, RAD 40 outboards were being fitted to 13 workboats in 10 locations as part of the £5.4 million ($7.13 million) ZENOW project spearheaded by RS Electric, which aims to promote the use of electric propulsion in harbors and marinas throughout the U.K. The company has also been active in the United States, with a RAD 40 powering the new, classically styled 26′ (7.9m) commuter launch designed by Stephens Waring and built by Belmont Boatworks in Maine.
It’s notable that in 2024 RAD secured £4.27 million ($5.7 million) in funding to help carry them into the mainstream—almost double their original target of £2.5 million ($3.4 million).
The Building Blocks
An outboard was just the starting point. The founders’ vision was to produce all the mechanical elements of an electric-powered vessel to the highest standard possible.
“The idea behind RAD was to make things very reliable and robust, highly digital, software-driven, and very autonomous,” says Daltry. “In almost all cases, our unmanned systems were very connected. Everything was connected back to one computer infrastructure where all the software could manage it. That was then connected to humans onshore. And so RAD was born of that same mindset but trying to build it in a productized set of building blocks, starting with our electric propulsion business.”
Courtesy RAD Components like throttles are modular and can be switched out by plugging the cables into the preferred module.
This modular approach means the various elements can easily be replaced. Take the throttles: You can have a single throttle or dual throttle, top- or side-mounted, simply by plugging two cables into whichever configuration you want. And RAD is currently developing a joystick control to replace the throttle and the steering wheel for those who want to dispense with them.
Because it’s digitally controlled, the system can all be linked to a computer and operated remotely. As Harry Beadle, RAD’s head of embedded systems, puts it: “It’s very easy to swap out a throttle and a steering wheel and put in an autonomy system because the outboard isn’t expecting a steering wheel, it’s just expecting a steering input. So, if a customer wants a robotic boat, they can put our drives on there, put a battery on it, and we have one cable that they talk to, and that’s it. It literally takes 20 minutes.”
A case in point is the Oceanus12 produced by Zero USV (Plymouth, Devon). The 40′ (12.2m) boat has been developed as “a fully autonomous, low-carbon unmanned surface vessel designed for over-the-horizon missions.” It has been fitted with a hybrid propulsion system made up of two RAD 40s, two batteries, a generator powered by hydrotreated vegetable oil, and some solar panels. The boat is capable of going to sea for several weeks with complete autonomy while being monitored from a computer at company headquarters. Try that with conventional outboard controls.
Even manned vessels can benefit from this connectivity. RAD is currently working with the University of Plymouth developing a fleet management system to help in the transition from internal combustion to electric propulsion. The system measures a boat’s speed, position, engine RPM, fuel-injection rate, and other data while using a conventional engine and then analyses the information to calculate the potential savings by switching to electric. The information can also be used to calculate the optimum propeller for a boat.
“Lots of people think they spend 70% of their time at full speed,” says Beadle, “but actually most people spend much more time at lower speeds. Having that evidence allows you to design more appropriate propellers. People often over-specify batteries, too, and you might find you need smaller batteries than you think, which will increase your savings. You can even spot if a driver is driving a bit heavy-handed and, with that real-world evidence, put them on a training course and save some carbon that way.”
Drop-in Electrification
Another clever idea to come out of the RAD offices is their all-in-one console unit comprising a battery box/seat with a steering wheel, throttle, their so-called RAD tag (i.e., a remote key/kill cord), and either a 21-kWh or a 42-kWh battery. The whole contraption, along with the outboard, can be shipped to where it’s needed and fitted to almost any appropriately sized boat to give instant clean, silent propulsion. No need for deep technical expertise—just fit the outboard to the transom, attach the console to four secure points, plug it all together, and you’re good to go. To make it even easier, RAD has teamed up with RIB manufacturer Zodiac, which has incorporated cleats on the floors of certain boats to accommodate RAD console attachment.
Courtesy RAD The combined drop-in battery box and steering console simplifies construction and systems installation for builders looking for an accessible electric propulsion option for smaller boats.
This off-the-shelf approach has obvious benefits for medium- to small-scale boatbuilders, who may not have the skills in-house to fit an electric motor—particularly those with a 400V architecture.
“We know the future of higher-power electric boats is high voltage,” says Daltry. “It’s physics; it’s obvious. There’s been a little bit of reticence in the market about it, principally because lots of boatbuilders are not comfortable with high voltage. We can deliver complete solutions to boatbuilders. We can provide the expertise, train their people in assembling and commissioning so that it’s all completely safe, provide all the necessary paperwork and risk assessments, and even help write manuals to make sure their customers understand how it all works. We see this as a mission. Our goal is to make it possible for every boatbuilder to be able to offer electric products in their lineup.”
Aaron Porter The tidy battery box and console installations are possible in part because all connections for steering and throttle control are electrical, not mechanical.
Under Way
Having heard so much about their technology and hardware, I was keen to try it out for myself, and RAD duly obliged with a test drive. So, one bright September day, I headed down to the scenic River Hamble, a stone’s throw from the RAD office, with Beadle and Sam Pickering, head of products. Moored up at the dock was a high-density polyethylene (HDPE) Willelectro workboat complete with landing-craft-style bow ramp and powered by twin RAD 40s connected to that ingenious all-in-one console.
Nic Compton RAD’s Harry Beadle and Sam Pickering put the twin outboard Willelectro workboat through its paces on the River Hamble.
For anyone accustomed to the roar of an outboard or the putt-putt of a diesel, it’s disconcerting to climb aboard an electric-powered boat and set off without any of the usual preliminaries and startup rituals. Pickering spared no time in getting us out of a tight corner—even without a bow thruster, the twin engines with 180° rotation make maneuvering in tight quarters a doddle. When I persuaded him to open up the throttle, I experienced an on-water equivalent to the famous G-force snap you get while driving an electric car as the boat leapt forward without any preamble or hesitation.
Once well clear of potential obstacles, I took the helm. After a lifetime of driving boats with dodgy old push-pull throttles, the sensitivity of the bespoke RAD controls took a bit of getting used to. This, it turns out, was the slightly desensitized version; the more sensitive version had proven too “nervy” for inexperienced folks like me. It didn’t take long to get comfortable and confident running the boat in open water, though I declined to moor the boat on our return, just in case. That gave Pickering a chance to show me the RAD 40’s party trick. That 180° rotation means the boat can spin practically in its own length, and we were soon pirouetting around in the middle of the river in merry circles. It was an impressive performance, even if it did put me off my lunch. From a practical point of view, the enhanced maneuverability showed that the outboard’s turning angles are much more than just a gimmick.
Courtesy RAD The 180° articulation of the outboard’s lower unit makes for amazing maneuverability, such that even single-engine boats can turn easily in their own length.
As we headed back to shore, Beadle returned to the car theme. And it turns out the comparison with Tesla isn’t so far-fetched.
“A lot of what we do uses automotive technology,” he said. “There’s so much investment into electric cars, and we get to piggyback that. So, if a new battery chemistry comes in or if a new motor architecture comes out, that’s something we can fold in—and that helps to bring the price down as well.
Typically, the marine industry lags the automotive industry by many years, and there’s good reason for that—obviously a lot of work goes into marinizing an entire combustion engine and you want something reliable. But we’re managing to be right on the edge of the electric vehicle technology. There’s no time lag. What’s in our drive is what’s in the current state-of-the-art electric car.”
With the RAD 40 fully launched and most of the supporting infrastructure now in place, the team are now turning their attention to broadening the company’s range of products. A 120-kW model (rated at 160hp) is currently in development for larger craft, as well as a smaller model currently known as the RAD X because its size hasn’t yet been finalized—though it’s likely to be in the 5-10 kW range, tiller-steered, and powered by a 48V battery.
Meanwhile, the company continues to go from strength to strength, with a new office opening in Charlestown, South Carolina, from which their collaboration with Zodiac and other American companies will no doubt continue to grow.
The future looks bright and, well, pancake-shaped.
Competitive Comparables
While far from mature, the marine electric-propulsion market has outgrown niche status. New players come and go with invigorating regularity as technologies are developed or adopted from other sectors. It’s exciting to keep up, but pity the poor boat designers, builders, and service technicians challenged to keep current. With that in mind, below are a few existing competitive companies with broadly comparable offerings to RAD’s—at least for now.
RAD 40 SPECIFICATIONS
Power 40 kW
Rated horsepower 55-60hp
Voltage 400V
Propeller speed 2250 rpm
Weight 98kg (216lb)
Steering angle ±90°
ePropulsion X40
The X40 is the biggest in ePropulsion’s line of electric outboards, which includes the X12 (rated at 15.6hp) and the X20 (rated at 26hp). Like the RAD 40, the X40 has electric steering and throttle that can be integrated into a digital management system. The manufacturer claims the engine is 60% smaller and 65% lighter than the equivalent gas outboard, with 88.2% efficiency. An interesting feature is the integrated hydro generator, which allows you to recharge the battery while sailing or being towed. Visually, the X40 is very different from the RAD 40, being tall and upright, with the motor located underwater in the propeller pod.
X40 SPECIFICATIONS
Power 40 kW
Rated horsepower 52hp
Voltage 96V
Propeller speed 1500-2100 rpm
Weight 99kg (218lb)
Steering angle ±45°
Elco EP50
Elco (aka the Electric Launch Co.) has been making electric boats since 1893, including building the U.S. Navy’s first commissioned submarine in 1900, so they know a thing or two about the subject. They took a break from electric power for most of the 20th century but returned to the market in 1987 and, with renewed vigor, in 2007. They now offer a range of six electric outboards from 5hp to 50hp (they prefer horsepower to kilowatts). The EP50 is available with a tiller or remote (electric) throttle but not electric steering.
EP50 SPECIFICATIONS
Power 26.4 kW
Rated horsepower 50hp
Voltage 96V
Weight 87kg (190lb)
ExploMar Wave 70+
According to its YouTube channel, ExploMar is “a visionary ecological company leading the charge in electrifying water mobility”. The company is based in Shanghai, China. The Wave 70+ is the smallest in their range of electric outboards, which goes up to 300hp (225 kW). Like the RAD 40, the Wave 70+ is fitted with an axial-flux (aka “pancake”) motor, with steer-by-wire and a closed-circuit cooling system.
WAVE 70+ SPECIFICATIONS
Power 60 kW
Rated horsepower 70hp
Voltage 350V
Propeller speed 3,500rpm rpm
Weight 80kg (176lb)
Steering angle ±30°
Torqeedo Deep Blue 50 R
Since the company was created in 2005, Torqeedo has been at the forefront of the electric outboard revolution—and usually several miles ahead of most of the competition. They led the way again with their high-voltage Deep Blue range of outboards, launched in 2014. Since 2024, the company has been owned by Yamaha. Torqeedo now offers two high-voltage outboards (alongside their 10 smaller outboards), rated at 25 kW and 50 kW. Like the RAD 40, the Deep Blue 50 R has modular elements and a “fully integrated propulsion and energy-management system.” Unlike the RAD 40, it has an axial-flux motor located in the propeller pod. The company claims 89% efficiency.
DEEP BLUE 50 R SPECIFICATIONS
Power 50 kW
Rated horsepower 80hp
Voltage 350V
Propeller speed 2400rpm
Weight 139kg (306lb)
About the Author: Nic Compton is a freelance writer/photographer based in Devon, U.K. He lived on boats in the Mediterranean until the age of 15 and worked as a boatbuilder for many years before swapping his chisel for a pen and his router for a computer. He sails a Rhode Island–built Freedom 33, currently based in Greece.
