While it’s way too early to share details of Pete Sewell’s tests of the electric motor he’s put into WHIO (the original AROHA in New Zealand), we can definitely say that the tests are making it clear that an electric drive for this boat is not only possible, but probable.
It’s even sparked discussions between Off Center Harbor and Brooklin Boat Yard of a much largr 40-something-foot version with an electric drive.
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Mark Fort says:
Coffee is way too expensive in Warkworth. Great job with the electrics, Peter Thompson is keeping me up to date with your progress. Can’t wait to get back to NZ to see for myself!
Chris Latchem says:
Very smooth, and quiet…
Dave - SeaStorm Marine Australia says:
Super Encouraging! Love your work.
Glad to see that you are working with lower rpm, more efficient props.
This is one of the bonuses of going electric.
Robert Harrison says:
I have been sailing a 27-foot, 3200 ib. H-Boat for the last six years. About 3 years ago I switched from a 2 HP 4-cycle OB to a Torqeedo 3 HP. I’ve been very pleased with electric v. gasoline.
For several reasons, I am about to have a 6 HP electric pod drive from ePropulsion installed. I had three 915 Wh LI batteries for my Torqeedo which has provided very ample range. The new pod drive will have a 4096 Wh LiFePO4 battery.
Robert Harrison says:
Replying to myself to add some info on Watts used at different speeds for my boat with a Torqeedo Travel 1003 in glassy water (I sail on a lake):
Knots Watts
4.0 810w
3.5 560w
3.0 400w
2.0 110w
David Smyth says:
I have an Olson 40: George Olson designed in early 1980s as a ULDB, 36′ waterline, about 10,000 lbs displacement.
I removed a 3GM30F Yanmar, transmission, the fuel tank, 4xT105 batteries, muffler, and all the associated gear, special tools, fluids and spares, which in total including 30 gallons of diesel weighed about 700 lbs.
I installed, in a weekend by myself (easy!), a 10kW Electric Yacht motor, derated to 4.75kW due to my 5KWh bank of LiFePO4 batteries being limited to 5kW discharge rate.
At 4.5kW power setting, my electric motor pushes the boat — same prop, same shaft — at EXACTLY the same speed as I got from the Yammer at full throttle!
The Electric Yacht motor, reduction, LiFePO4 batteries, and cables in total weigh about the same as the 30 gallons of diesel. Also, I removed the LPG tanks and stove, replaced with an induction stove that weighs about 2 lbs, so another 100 lbs saved there. So over 600 lbs removed from the boat by removing all fuel and going all electric.
As mentioned elsewhere, I easily get 5 days, and with a bit of care can get 6 days, of local cruising without solar (right now, I can only charge using shore power). Refrigeration remains the primary consumer of power, with cooking second, and propulsion a distant third.
Motor sailing is the key — even in very light winds, when the sea is glassy, there is some wind, and when the boat is moved with even 500W to 1000W, the apparent wind doubles the boat speed. We have motorsailer on glassy seas, main and jib, for 20 miles at 5 knots using a total of 1kWh.
With no sails up, light wind and chop but two way average, here are measured results:
4.61 kW — 2164 RPM — 6.15 knots
4 kW — 2044 RPM — 5.85 knots
3 kW — 1900 RPM — 5.45 knots
2.5 kW — 1800 RPM — 5.05 knots
2 kW — 1650 RPM — 4.75 knots
1.5 kW — 1500 RPM — 4.25 knots
1 kW — 1240 RPM — 3.7 knots
750 W — 1130 RPM — 3.3 knots
500 W — 950 RPM — 2.5 knots
Philipp Schietinger says:
Hello Robert, I have been eyeing the 6hp Epropulsion pod as well, now I am curious as to what your first impressions will be!
charles flanagan says:
Brian
I installed a Torqeedo motor in an inboard configuration in a Horizon Cat with great results. Used four 200AH Odyssey bateries. Those were about 130# each and about $600 each. Lithium batteries would only be about 1/3 of that weight but 50% more expensive. Article on boat is at: https://cpyoa.com/forum/index.php?topic=6926.msg50151#msg50151
although some of the pictures no longer print. Combination gave me all day cruisng range.
Brian Gillan says:
Thank you Charles. Appreciate your feedback. I’ll check out the video you mention.
David Smyth says:
Note that lead acid batteries at high current lose 80-90% effective capacity due to the Peukert effect. In fact, LiFePO4 batteries are much cheaper than lead acid when comparing usable power for propulsive loads. And they are much lighter and last more years.
Even for house loads, lead acid batteries are not cheaper than LiFePO4. On my boat, we can pretty easily get 5 days of power using LiFePO4, whereas we needed to charge every day on lead acid. Same name plate capacity, but at least 4x effective capacity.
Brian Gillan says:
I have an 18 h/p Kubota in my Grey Seal. It’s way to powerful for my boat (and heavy). Does anyone know the weight of batteries for an electric motor? I’m seriously considering a changeover. comments?
Edward Odenkirchen says:
So looking forward to this topic. Facing a Yanmar rebuild or swap out, I am seriously considering a refit to electric for my 8m sailboat. Friends warn me I’d be destined to turning my vessel into a day sailer and lose my longer cruising opportunities.
Robert Harrison says:
Edward, the new ePropulsion outboards and pod drives feature regeneration – whereby the free spinning of the propeller while sailing will charge the battery. It’s a nice feature especially for a cruiser. On the flip side, ePropulsion is supposed to begin offering a folding propeller for racing sailors this fall.
David Smyth says:
Note that a folding propellor will not allow measurable amounts of electrical regeneration: however much power is required to close the blades — almost none at all — is the maximum amount that can be generated.
An Autoprop does work, however, and tests have shown them to be by far the best at regeneration under sail.
Feathering props can also work, but of course at a loss of efficiency (more drag for the charge generated) due to the lack of twist on the blades.
Peter Sewell says:
Well we used just on 3 kWhr of electricity, at 25c per unit there’s the 75c.
96 volt battery, most of the time drawing about 7 amps.
Keep in mind that my propeller only uses 80% of the power of a more stsndard prop at that speed.
Pete
Mike Wright says:
The vid wasn’t to clear about the amp hrs, but I’d be feeling cheated by the coffee, unless it’s high test!
Bill Kenneke says:
Excellent!
Can anyone break those numbers down for the electrilliterates like myself?
Is that amp hours that equal 75 cents? … and if so, how many is that?
Anyhow, can’t wait for more, get busy!