Cornwall Electric Boat

Cornwall Electric Boat A Cornwall-based project by Bob Shillito to convert a boat to electric power. Posts explore the options and explain the decisions.

It's intended to share experience and promote wider replacement of diesel and petrol engines with electric power.

09/08/2022

Job done! The project is complete and this is the result:
- It works. You can take a 60 year old boat and convert it to electric relatively easily (fixing the boat is a much bigger job).
- Theoretical calculations on power, speed and charging turned out to be surprisingly accurate.
- The boat will cruise quietly at 4 knots using 1.1kW of power (max engine power being 4kW) with a range of about 19 miles: 4.5 hours. At 3 knots, you could do 10 hours.
- The top speed is 5.8 knots at 2.9kW. That's the 'hull speed' for a 19' boat, anyway. Over 2kW of power, the boat doesn't go much faster; you just make a bigger wake.
- The solar panels will produce enough power on one sunny day (1.6kWh or more) to top up the batteries after a typical outing.
- The four lithium batteries hold a total of 5.12kWh, which is plenty for this leisure application.
- The technology, particularly the bluetooth apps for monitoring battery status and solar charging, is really good.
- The Waterworld 4 electric motor is a fine piece of engineering. It is quiet, smooth and very nice to use.

This is what it's all about!
18/07/2022

This is what it's all about!

18/07/2022

The first two trials were completed on a couple of perfect summer mornings. Terrific performance from the motor, batteries and the solar array, which collected 1.6kWh on a single day between the two tests, fully recharging the batteries.
More to the point, it was great to enjoy a couple of hours cruising the river with Lynn, Jack and Denise!
More detailed tests to follow, now that the boat is on its proper mooring.

Swift is launched at last - and all systems appear to work. Five months of boat renovation, followed by just a few days ...
13/07/2022

Swift is launched at last - and all systems appear to work. Five months of boat renovation, followed by just a few days installing the electric motor and systems. Trials now commencing to see if the reality matches the calculations: boat and motor performance, range, solar charging, etc.

All systems installed and tested: solar and mains charging; all the power and control cabling. Take a deep beep breath a...
06/07/2022

All systems installed and tested: solar and mains charging; all the power and control cabling. Take a deep beep breath and turn the motor on for the very first time. All works perfectly.
Ready to launch!

The boat renovation is complete, the motor is in, the solar panels are on. It's all coming together. Just a load of wiri...
24/06/2022

The boat renovation is complete, the motor is in, the solar panels are on. It's all coming together. Just a load of wiring and commissioning to do, ahead of launch day. And make sure that the bilge pump works 110%.

Testing the solar array before installation. The success of the project depends to some extent on the efficiency of the ...
22/06/2022

Testing the solar array before installation. The success of the project depends to some extent on the efficiency of the solar, so a test was needed. Charging the batteries on a sunny day for about 3 hours produced 800Wh (according to the interface on the Victron charge controller). That means that a full day's charging could be expected to produce about 2kWh - or 40% of a full charge. This is roughly as planned but good to see it confirmed. The actual maximum charge rate was 235W as compared to the theoretical maximum of 330W - so not bad. Slightly less good news was that if any part of the array is shaded, the charge rate plummets.

On to the technical stuff, at last. Figuring out how to mount the motor in perfect alignment with the propshaft. Timber ...
29/05/2022

On to the technical stuff, at last. Figuring out how to mount the motor in perfect alignment with the propshaft. Timber bearers to take the engine mounts are required.

Two months of repairs and renovations are coming to an end - getting the boat into a condition worthy of her new electri...
11/04/2022

Two months of repairs and renovations are coming to an end - getting the boat into a condition worthy of her new electric propulsion. Here cutting out new windows to replace the ugly ones. Lots of painting to complete, then the tech installation and hopefully Swift will be good to go in May.

About charging and solar panels. It's all very well having an electric motor and batteries but how do you charge them? M...
24/01/2022

About charging and solar panels. It's all very well having an electric motor and batteries but how do you charge them? Major marina companies are busily installing fast charging points on pontoons. On the Fowey River, the best we have at present is standard mains pedestals on pontoons at Penmarlam.
With the boat on a mooring, solar is the answer if we do not use the boat every day - but we also need a mains charger for when shore power is available.
48V battery arrays are much less common than 12V or 24V, so there is a limited range of equipment for charging. Victron make a 48V, 25A charger (i.e. 1.2kW = about 5 hours for a full charge) and also appear to be the market leaders in solar charge controllers. I selected one of their MPPT solar controllers (MPPT being the most efficient charge system) which will output at 48V. The solar panels were selected on the basis of the maximum possible size: 3 in total: two on the fore cabin and one on the cuddy. They also need to be pretty flexible to cope with the 48mm curve per metre of the cabin roof.
I selected reasonably-priced Sunpower 110W panels and calculate that in the summer, we will accumulate about 1kWh per day, after allowing for the panels facing upward and not directly at the sun - so completely flat batteries would take 5 days to fully recharge. In practice, I'm hoping that a couple of sunny days between uses will be OK, or take a trip to the pontoons.

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Fowey
Par
PL242SA

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