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Message board > Engines > Converting Hardy 25 to electric propulsion?

Message 6 of 6
Posted by member Andrew Barwick on Tuesday 1 January 2019

Hello Phillip
As a fellow Hardy 25 (1989) owner I am very interested in your project. My boat which also has a Mercruiser 4.3 V6 petrol engine with Alpha 1 leg is currently based in Portsmouth but I hope to use it on the non tidal River Thames in future and an electric drive would be good where we have a speed limit of 4 knots. You mention achieving 15 knots which seems like a "big ask". My current top speed is 20 knots at 4,300 rpm with clean hull on flat water using a downsized propeller size 16 inch diameter / 13 inch pitch. I would guess that my engine is producing around 160 to 170hp at this speed, so you would probably need about 130 hp. to get 15 knots and my boat is not fully on the plane at 15 knots.
I would love to hear how you get on with the project. I was also interested to hear that your 25 has a Mercruiser 4.3 petrol engine as I have heard that Hardy made only a very few 25s with that engine out of a total of 75.
Good Luck - Andrew Barwick

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Message 5 of 6
Posted by member Peter Cox on Monday 3 December 2018

Have you tried the Electric Boat Association?

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Message 4 of 6
Posted by member John on Saturday 1 December 2018

Hi Phillip.

An interesting idea. However to maintain 15/16 knots would require enormous battery power! (and battery weight). Displacement speeds of 3/5 knots may be more practical and I think such systems are already in use on canal/river boats. A couple of links http://www.hybrid-marine.co.uk/12.html and http://www.hybrid-marine.co.uk/resources/Broad+beam+rev8.pdf may give the idea. But even then these are hybrid battery/generator/engine systems to maintain the cruising range and in barge type vessels with lots of room for the batteries!

But let us know how you get on - big saving in diesel in sight - even the new Isle of Wight ferry is a hybrid!

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Message 3 of 6
Posted by member Hardy Editor on Friday 30 November 2018

Ahoy again Philip,

I've found the information and I will email it to you in a moment. Data protection and all that....
I spoke to this chap in 2008 as I was interested in the idea myself at the time.

All the best,

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Message 2 of 6
Posted by member Hardy Editor on Friday 30 November 2018

Hi Phillip,
Well I don't know of a Hardy that has been converted to electric, but I do know of a chap who did this quite a while ago to a Freeman. I will try and find his photographs and email to me and get back to you.

All the best,

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Message 1 of 6
Posted by member Rev Phillip G Hiscock on Friday 30 November 2018

Has anyone converted a Hardy 25 to electrical propulsion. Currently I have Mecruiser 4.3L with Alpha Gen1 stern drive. I would like to achieve a max of 15/16 knots. Does anyone know if it is feasible to 'go electric'? Is it possible to power the stern drive using an electric motor? Please forgive any naivety on my part. Thank you

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