First Electric Engine Performance Test

As part of the delivery of our boat, Oceanvolt sent a technician to certify the installation of all components related to the electric propulsion system, and test the engine performance.

We measured speed through the water at different levels of engine power, mostly in the protected channel of Les Sables-d’Olonne with no waves. Wind in the channel was low at around 5 - 8 kts, and we tested motoring upwind (around 40° TWA) and downwind (around 140° TWA). The centerboard was raised entirely for all tests (reducing the wetted surface and maximising performance).

All tests were done without the generator running, powered entirely from the battery bank (the generator is fairly quiet, by the way, allowing for comfortable passages even when the generator needs to be run).

Oceanvolt had done a calculation earlier of the power required to move an OVNI 450 (similar displacement, waterline 0.6 meters longer than the 430) through the water in various conditions so we were able to compare our results with the predictions.

Oceanvolt AXC24 Performance Plot

Our expectations were met completely and we are happy with the results, it shows that propulsion on this boat is very versatile and effective:

  • Very low power required to motor in harbors (2 kW for up to 4 kts); this kind of maneuvering can be accommodated within the daily power balance easily

  • Ability to maintain reasonable speed in calm/windless conditions (e.g. 5 kW for up to 5 kts); if this has to be sustained for a long time, you could run the generator 50% of the time (e.g. 2 hrs on / 2 hrs off), or run the generator full time for higher speeds (above 6 kts)

    • Running the generator full time (up to 6 kts) yields a theoretical fuel consumption of 3 l/hr or 0.5 l/nm, while running it 50% of the time (up to 5 kts) would equal 1.5 l/hr (averaged) or 0.3 l/nm (this is slightly more efficient than the Volvo D2-50 that is standard on this boat) - if you wanted to express the absolute range of the boat under engine only, it would be up to 1,100 to 1,800 nm, respectively (with the 550 liter main diesel tank)

  • Motor against strong currents at hull speed under maximum engine power; with the generator running, this speed can be sustained for up to two hours

  • Make headway into strong wind and big waves, if necessary

Applying maximum power (22 kW) corresponds to approximately 1050 RPM on the 19 inch Flex-o-fold folding propeller. 2 kW of power correspond to 500 RPM.

Due to the conditions this week, we could not test regeneration under sails yet, unfortunately. This will have to wait until we return to the boat in spring (Update: we now have some measurements on this).