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Old 09-03-2019, 11:14   #1

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Electric Machines

Anyone use electric machines rather than a diesel engine?

I saw a cat with twin electric machines on the market in Australia and it struck some interest.

I don't own a boat, I was planning to purchase a liveaboard around 40feet but my girlfriend gets seasick so I'm likely to stay kayaking instead. My loss. Not interested in cats; too scary.

However, I did study bachelor of engineering both electronic and electrical and enjoy picking trash out of our estuary hence thought....

An electrical machine can be housed below and watercooled via the same holes as an existing diesel.
The prop shaft could regenerate the battery bank while underway.
Downside would be long periods on the iron sail yet a through shaft machine with a diesel half power could series the prop shaft. A dog clutch at both ends of the machine could be used to engage disengage ..
# motor to machine generator.
#machine to propeller thrust or generator
#motor to machine to propeller thrust and generator or storm time full throttle.

If I get my way we'll be living in the local Karina the next many years while we save to cruise afar. Electricity is there to remove a fuel bill and further along a diesel could be introduced into series to extend voyage.. Would corrosion be an issue with an electric machine?
My chances of being truthful..?? 0.01%??

Idea might benefit someone else?
What do you guys/gals/ladies/men think of such please?

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Old 09-03-2019, 11:24   #2
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Re: Electric Machines

I assume you meant electric motor to propel the boat.
I use and electric motor for daysailing.

For longer distances I have an outboard.

Num Me Vexo?
A house is but a boat so poorly built and so firmly run aground no one would think to try and refloat it.
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Old 09-03-2019, 11:37   #3
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Re: Electric Machines

If your electric motor can recharge your batteries while it is propelling you then you have invented a perpetual motion machine.......
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Old 09-03-2019, 12:16   #4
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Re: Electric Machines

Greetings and welcome aboard the CF, Boatsie.
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"

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Old 09-03-2019, 18:03   #5

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Re: Electric Machines

Yes. Motor=machine
You're a winner.
Perpetual not. But constant wind would drive the hull and into turn turn the prop thus using the machine as a generator with a slight loss of knot. Not in a hurry where I'm from.
If nearer perpetual required one could use a magnetic machine where as the magnetic field is used to generate torque. Magnetics do lose magnetic intensity eventually as the magnet is the fuel source. Must be technology or rather lack of as to why freighters aren't invested into large horsepower large range magnetic drives. Future is future yet we near the future it's just the past.
We prefer sail too..

Thank you.
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Old 09-03-2019, 19:03   #6
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Re: Electric Machines

boatsie my GF is afraid of sailing so if SHE wants she can meet me and in the meantime if I have a female crew better for me.
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Old 09-03-2019, 19:22   #7
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Re: Electric Machines

Originally Posted by Woodland Hills View Post
If your electric motor can recharge your batteries while it is propelling you then you have invented a perpetual motion machine.......
I assume the OP means that you can use the spinning prop to generate electricitiy while under sail. Not perpetual motion.
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Old 10-03-2019, 03:13   #8

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Re: Electric Machines

Wtmf.. Love it

Yes. The prop to torque the machine.
I don't know cruisers. The biggest boat I skippered was a Dragon class 30 footer. She had heaps of cloth and if used to charge batteries she'd be easy to do such.
The cruiser we used was a RobLegg24. I think her keel is 350kg. She'd notice the drag. Currently out of commission with a broken kite pole down haul, a sliced kite lanyard, a broken starboard stay, a broken port spreader and a broken mast foot. But she goes really fast at 0100 in a gale with full sails on a broad reach. At least she did go really well.
We don't use engines much mostly due to pollution but knowing some of you guys have a much larger momentum and/or law requirements when berthing I thought I'd suggest the idea.. Might cost less in the long run due to fuel.

Another idea could include a split stator on the electrical machine. Eg. If seizure the machine could be disassembled easily at sea allowing the smaller diesel to torque shaft.
If I had a boat in need of a diesel rebuild or replacement I'd be researching such propulsion. Reduced failure to torque prop shaft, reduced fuel bill, maintenance cost low, spend cents instead of dollars.

Just a mind storm idea friend, when/if I buy a boat I'll probably keep the diesel until maintenance requires a lump spenditure.
Safe sailing.
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Old 10-03-2019, 05:00   #9

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Re: Electric Machines

I just like the idea bro.

Less fuel like a hybrid car.
Other ideas in case of sea urgency and failed machine could be,
Jack shaft assembly bypassing machine.
Spare Jack shaft with dog clutch couplings to replace machine. (4 bolt machine plus isolated electrical connectors). Maybe a gantry rail and pulley with mounts by side?

Cog ended prop shaft with twin side engagement? Machine one side, motor other?

Factory hybrid unit?
Sailors are cluey.
Glad if I could help.

I know my past grandads uncle bought a diesel car and only filled the tank with compost and scraps! Diesel recipes should be on internet.

2 years from boat here if budget true.
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Old 10-03-2019, 05:12   #10
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Re: Electric Machines

You can’t apply automobile thinking to a boat. Boats run on flat surfaces and don’t have brakes. Electric drive in a boat does not save fuel like in a hybrid car. And anyway, these days there are non-hybrid cars with same fuel efficiency as hybrid. But they cost a lot less and so aren’t considered “kewl”.

Do a lot of research and you find that electric propulsion is useful for getting the boat in and out of the harbor under mild conditions. But as a primary means of propulsion electric isn’t a workable thing unless you want to burn more fuel. Or maybe you like to sail in higher wind conditions to have extra power for regeneration. Even then regeneration isn’t very efficient because propulsion props are not that good when running “backwards”. It requires many hours sailing per each hour “machining”.
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Old 10-03-2019, 05:50   #11

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Re: Electric Machines

Transmitterdan. Thank you..
That's what I've been looking to find. Wasn't sure/ didn't know if the prop would drive the shaft..
Yet if I wasn't idiotic with a search I'd be further retarded in gaining such knowledge.
Easier again. Thank you

Do you guys/gals/ladies/men with large volume accelerate from chain with cloth ok? My experience is minimal and light boats do it easy off dock or chain. I should have remembered the cavitation and lack of reverse thrust. Just dislike motors. (I was a paid helmsman of a motorboat).
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Old 10-03-2019, 12:48   #12

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Re: Electric Machines

Tons of threads on electric propulsion, some including hydro generation under sail.

Most posts are by wishful thinking dreamers, but some do get into great technical details that are helpful for any well-funded pioneers not too worried about economic practicalities.
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Old 10-03-2019, 20:09   #13

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Re: Electric Machines

Thanks John,

Doubts I have include under powered and short running time.
I've only seen 1 storm! We came into the cove on fumes and with all of the iron sail forward thrust we had been going backwards many hours.
Battery technology has improved much. Machines will follow. I agree, at moment it's dollars until someone uses sense to remove scents and make cents. Lots of boats out here.
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Old 10-03-2019, 21:04   #14
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Re: Electric Machines


There are numerous electric replacement systems currently commercially available. They do indeed use spinning props to regenerate power under sail, exactly like electric cars have regenerative braking.

These systems consist of battery banks, extremely sophisticated control systems, and usually brushless motors and gearboxes.

That last one is cheap, but you have to create your own mount.

The trouble with these systems is range - great to be just getting in and out of a harbour. Without shipping huge battery banks, you can get 15-20 miles out of a charge out of a system that weighs as much as a diesel + fuel combo.Not really practical, considering the diesel will go hundreds of miles on a tank. But if don’t mind bobbing around till the wind is up, they are attractive.

That being said, some guys are doing long distance, but the gear is very pricy, tons of solar, makeup genset, and custom boats to fit it all.

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Old 11-03-2019, 01:10   #15

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Re: Electric Machines

Cheers Matt.
Saved the internet sites.

From my prospective.
Future boat. Hoping 36-55 feet ish. Probably 40.
Our marinas are cove design: they don't flush well. A small electric could be ideal during most conditions.
From teachings, we rarely use iron sail. Harboring, currents on shoal, mostly recharge batteries. Basically 1-3 hours per week.
But storms happen. Seen a 5 dayer with 3 days exceeding 70 knot. We'd be with Davey Jones collection if without a long hour iron sail.
Researching through shaft electric machines to aid docking, spin prop at dock, generate electricity at sea using diesel and basically not much different to existing layout if layout has ability to extend internal shaft length and mount diesel farther forward.
Wouldn't matter if it's not a big electric machine, as long as it can be hoisted or moved out of the way and replaced with a Jack shaft at sea. Solar panels, yes.
That's where one of my researching time is used.
Cutting diesel to 1-3 hours a week, if not to charge due to panels, maybe just to lubricate.
Marinas are fairly oily nowadays.
Loving sailing (or bobbing playing games like, " ripple ho, wind ho, man overboard ho, "
Thank you.. I'll read websites later.

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