How I found the right electric engine for my boat after spending £25k

Felix Marks explains how he turned around the disastrous electric engine installation on his Tofinou day-sailer

The new Voltsport motor installed on Felix Marks' boat. Credit: Felix Marks Credit: Felix Marks

You may have read the sorry tale of Penelope's Oceanvolt electric engine project back in the July 2024 edition of PBO ('Why changing to an electric motor was a disaster').[1] After the Yanmar D13 inboard diesel engine in my Tofinou 7 day-sailer, Penelope, failed after many years of service, I decided to replace it with a marine electric motor.

After consulting Oceanvolt in Finland, I selected Oceanvolt's AX3 shaft drive motor. The project started during the pandemic and was full of hope and ecological ambition, but it turned into a disaster.

The Tofinou 7, Penelope. Credit: Felix Marks

After only one year, Penelope's motor had become badly corroded. It completely failed to function over the course of a lost sailing season. Oceanvolt refused to cover the motor under warranty because of the way that it had been installed, even though I had paid them handsomely to sign it off.

The total project costs were over GBP21,000; the future of my boat looked bleak, and a return to diesel seemed inevitable.

Finding the right electric engine

After a lot of heartache, and rather than immediately reverting to diesel, I thought I'd at least explore the rest of the electric engine market. I'd already invested in everything surrounding the motor, including spending thousands on lithium-ion batteries[2], a charger, wiring and instruments. Perhaps I could slot in a new motor from a different manufacturer?

A key post-Brexit lesson learned from the previous experience was to avoid dealing with a non-UK based supplier of the technology. A little research suggested a couple of alternatives to Oceanvolt, including WaterWorld and Fischer Panda. I liked the look of Elco too, but I couldn't find any UK representation.

The corroded state of Penelope's original electric motor.

Credit: Felix Marks I started with WaterWorld, which is represented in the UK by Henley Technical Services. Their website suggested the team had a lot of experience with marine engines, so I arranged to visit Steve Hoile at his business just outside Henley, to view the WaterWorld technology.

Steve kindly picked me up at the station. We got chatting and I explained the background of the failed project. He started showing me some of their current installation projects and the WaterWorld technology.

Steve had already sent me a quote for a replacement motor and controller.

Steve Hoile has installed numerous electric engines, including this 10kW WaterWorld installed in the gentleman's launch Tarbes II. Credit: Felix Marks Since Henley is, of course, on the Thames, Steve's electric motor customers are primarily operating craft such as slipper launches.

Some way through his sales patter, Steve then stopped and said: "You know, I really think it's possible to repair your set-up. Even if it means a new motor and (in the worst case) an engine controller, it would still be cheaper than starting again." In other words, he looked at my situation and wondered, what was the best thing to do, and not simply how to make more money selling me an entirely new setup.

How often in life does this happen?

Electronics experience

Given Steve's long experience and considerable expertise in marine electronics, including the installation of many marine electric motors, I thought I'd make a proposal. Would he allow me to pay him to cast his eyes over my boat and make some recommendations? His eyes lit up with the prospect of a challenge that would broaden his experience but, just as importantly, give me a chance to recover from the disaster.

Steve did not profess to have any Oceanvolt expertise or experience, but reckoned he'd be able to feel his way through it. A couple of weeks later, Steve visited Penelope on the Berthon hardstanding in Lymington.

Moisture had penetrated the motor's encoder. Credit: Felix Marks

He speculated that the external corrosion on the motor was probably mirrored by a failure in the interior, most likely the motor encoder, judging by the fault codes shown on the Oceanvolt display. He offered to take the motor and its controller back to his workbench in Henley, which I readily accepted. Steve was now working on time and materials and his first bill was a little over GBP400, including VAT.

Was I about to throw good money after bad? A few weeks later, I heard back from Steve, who'd put the motor on the bench and had a close look. His findings were:

• Having measured the output from the sin/cos encoder (which is an integral part of the AX3 shaft drive motor) it's clear that it's degraded.

  The output voltages do kind of vary with the position of the shaft but they're all over the place and inconsistent. The little encoder PCB [printed circuit board] sits inside a chamber at the rear of the motor, this is what I found when I opened it up. You can see from the condition of the screw heads it's been very damp inside for a long period.

  Not actually underwater but close. Considering there is a close-fitting cover (not quite sealed, unfortunately) over the chamber the level of corrosion is surprising. Could water have been dripping over it?

  It's more than I would have thought possible from condensation alone. Anyway, the damp has got to the encoder.

• The motor itself is showing similar symptoms of extreme damp over a long period. Peering into the rear stator housing, I saw serious rust.

  In spite of the scary appearance, it is at the moment cosmetic.

• The controller looks generally OK inside but the atmosphere has been fairly bad in there too. I'll need to clean up a couple of the connector PCBs just in case. This is the worst one, not too bad.

So what to do next?

My existing defunct motor that Oceanvolt used in their AX3 motor assembly was made by Motenergy, the original (OEM) manufacturer. Steve recommended a new like-for-like replacement motor, which he could buy from Voltsport for GBP678+VAT. The justification for buying a new motor rather than trying to fix the old one was "because it was not crazily expensive and you'd get new bearings and avoid any potential issues which could have been lurking inside".

Steve warned there could be more than just one issue with the installation, specifically problems with the Curtis motor controller, so fingers were crossed that this was not the case!

Electric engine bombshell

After Steve had obtained the new motor and started installing it, his curiosity led him to question whether the Oceanvolt System was fit for the job in the first place. Clearly, the motor was not suitable for a very damp atmosphere, as confirmed by Oceanvolt previously. He commented that "the controller was much better protected, but it was weird that having done such a brilliant job with all the water-resistant connectors, the box itself was not sealed."

Would a WaterWorld system have survived in the same conditions? Steve said, "possibly as it has an IP (Ingress Protection) rating on the controller, but some of the data connectors are not as good as Oceanvolt". Steve said that the older systems he sees on the Thames from Stelco can survive long-term damp, but not long-term extreme damp like inside Penelope's motor compartment.

Then the bombshell from Steve. Further research showed that the original motor manufacturer, Motenergy, actually makes a water-resistant equivalent of the motor that Oceanvolt chose. The enclosed (sealed) motor is 50% more expensive and is designed to cope with damp marine environments, unlike the one Oceanvolt chose.

Also, it doesn't require water cooling when de-rated for 90A operation, thus making it a suitable choice for this installation. I asked Steve whether he thought the motor failure would have occurred if Oceanvolt had used the Motenergy enclosed (sealed) motor; he said he thought not.

Further electrical damage

But the story wasn't over yet. As Steve tested the whole system, he discovered that the Oceanvolt cockpit display had failed due to water ingress from the button, which had caused damage to the display circuit, including the ARM chip connections.

This was another big surprise, given this was down to the component and not the installation.

Damage to the ARM chip in the display unit. Credit: Felix Marks How often have you seen a cockpit display failing due to water ingress?

Furthermore, the display wasn't even located inside the engine compartment. Steve reported this to Oceanvolt, which this time decided to supply a replacement free of charge. The last significant area was cabling in and around the motor controller box.

Steve's report was as follows:

• There was a serious issue with the 6-pole Deutsch connector and the PCB (printed circuit board) into which it was soldered, carrying the signals from the motor sensor to the controller. I found that if I lifted the cable from the motor to certain angles, one of the four signals was cut and the motor stopped instantly. I could not identify exactly what was happening here - I cleaned the Deutsch pins and sockets individually and wiggled the various bits of the assembly but, annoyingly, couldn't identify exactly what was going on.

  I resolved the issue by removing the Deutsch assembly from the circuit and wiring a 4-pole cable from the Ampseal plug on the controller to the outside world via a 4-pole Superseal connector. I improved the diagnostic port by enclosing the usual Molex Minifit connector in a waterproof plastic casing.'

So now Steve had reviewed, tested and improved the entire set-up and was ready to help install it back into Penelope's engine compartment. Steve was also at pains to point out that the technical support he'd received from Oceanvolt in Finland was excellent.

Bringing my electric engine back to life

My friend Patrick Crowley (an immensely practical person), my wife and I met with Steve back in Lymington, and we all set about re-installing the new motor and its improved controller.

We spent some time wrestling with the reinstallation of the controller in the confined space. The motor itself was reasonably easy for Patrick and Steve to attach to the engine frame. Once the motor was bolted back into place, the three large motor cables were easy to secure.

Attaching the new electric motor to the engine frame.

Credit: Felix Marks Then it was time to test the assembly before completing the installation. Mercifully, everything was working perfectly.

The controller was secured back into place inside the engine compartment with its improved connectors. The wire loom then needed some careful attention to ensure nothing got near moving parts when the compartment was closed with the electric engine in operation. So, the good news was that everything was working again, and Penelope was ready to sail.

It's important to ensure the drive belt is properly aligned and tensioned.

Credit: Felix Marks Steve had heroically managed to fix Penelope's electric motor assembly and had got to the bottom of the causes of the problems. Along the way, he discovered that the main issue, the corroded electric engine failure, was avoidable if the manufacturer had selected the enclosed (sealed) motor, which was available from the same original manufacturer at a 50% premium of roughly GBP400.

After Steve's initial visit, the costs, including fault finding, remedial work, replacement hardware, testing and reinstallation, were GBP3,400.

Wiring loom makes installation easier; just make sure it is not near any moving parts. Credit: Felix Marks

A plan for protection

The last question, now that she's up and running again, is: how will the unprotected motor's exposure to the damp environment be managed? Clearly, the situation would repeat itself if everything were to remain the same.

Felix has now installed a temperature and humidity logger so he can monitor the moisture in the engine bay.

Credit: Felix Marks I considered whether to deploy a dehumidifier when she wasn't being sailed. For a machine to capture the moisture and send it out of the boat, it would also need a pump to help the water defy gravity on its way over the gunwales.

A second thought occurred, though. Why keep the engine compartment, located directly over the bilges, closed between sails?

The controller installed inside the engine compartment, with new connectors. Credit: Felix Marks

The boat's cover keeps the weather out, and with the compartment open, air can move freely and prevent moisture from forming inside the compartment. So far, this has worked. Even on a rainy day after many previously rainy days, no moisture has formed around the motor.

To satisfy curiosity and to do things properly, I also installed a temperature and humidity logger alongside the motor assembly for ongoing monitoring.

Lessons learned, again

The July 2024 article included several lessons learned, the first being:

• Don't assume that your boat is dry enough for an electric motor. They need to be installed in a dry place.
• Although the above point stands for most of the motors currently available, not all electric marine motors are equal. If you want to install one into a harsh (marine) environment, make sure the motor is enclosed (sealed).

  Also make sure that the plugs, wiring, and controller are fully protected from moisture. In my case, Oceanvolt had done a good job with the connector selection but not at all well with the motor itself.

• Perhaps the most significant lesson learned from the July article was the one from PBO's editor. If I had read the International Council of Marine Industry Associations (ICOMIA) report[3], which concludes that using sustainable biofuels, such as Hydrotreated Vegetable Oil (HVO) in conventional internal combustion engines may be better for the environment than switching to electric propulsion, I'd perhaps not have embarked on this project in the first place!

Editor's note: Practical Boat Owner contacted Oceanvolt for comment on this, Felix's second article, and the points raised.

It also asked about the decision by Oceanvolt to discontinue its entire AX shaft drive motor range, including the AX3. Oceanvolt declined to comment stating: 'While we initially provided comments, we were disappointed to see them portrayed out of context. We will not be offering further comments, as this article appears to prioritize sensationalism rather than constructive reporting'"

Oceanvolt said its decision to discontinue the AX series was made in 2023, long before the described events and for entirely different reasons. PBO shared with Oceanvolt a final copy of the original article published in July 2024 ahead of publication; it did not respond, despite repeated attempts to obtain a response. Within the original July 2024 article, PBO ran the company's full response.[4]

Previously, Oceanvolt has stressed that it was not responsible for the installation of the original electric engine. It highlighted that in relation to the GBP21,000 costs, the Oceanvolt electric system's price was EUR5,756 (GBP4,911) and that the total cost 'likely encompasses components unrelated to our system'. It stressed that its systems are designed 'for minimal ongoing maintenance under standard conditions, but due diligence in the installation environment and proper ventilation remain essential for both boat owners and installers.'

Regarding warranty support, it said 'the withdrawal of assistance was rooted in the identified corrosion during the installation stage, not covered under our warranty. We stand firm on this decision, stressing the importance of adhering to recommended installation conditions for optimal system performance.' 'In conclusion, Oceanvolt remains committed to providing practical solutions for boats.

We underscore the significance of meticulous care during installation and usage, recognising the collaborative effort required for successful outcomes,' the original statement from Oceanvolt said.

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References

1. ^ sorry tale of Penelope's Oceanvolt electric engine project back in the July 2024 edition of PBO ('Why changing to an electric motor was a disaster'). (www.pbo.co.uk)
2. ^ ithium-ion batteries (www.pbo.co.uk)
3. ^ he International Council of Marine Industry Associations (ICOMIA) report (propellingourfuture.com)
4. ^ original July 2024 article, PBO ran the company's full response. (www.pbo.co.uk)
5. ^ are available through Magazines Direct - where you can also find the latest deals (www.magazinesdirect.com)
6. ^ Facebook (www.facebook.com)
7. ^ Instagram, (www.instagram.com)
8. ^ TikTok (www.tiktok.com)
9. ^ Twitter (twitter.com)