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Old 22-03-2022, 13:06   #466
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Re: Replace Diesel with electric engine

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Sailing Wisdom I believe is using two motors in series if I remember correctly. There are many variables to consider. Should have an electric boat section in forum. The motor section in there now is filled with diesel problems.
Sailing wisdom the sailing Channel yes two motors and iirc wired for one forward and other for reverse / regen . But I was talking about Sailing Wisdom as I the thought process.
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Old 22-03-2022, 13:08   #467
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Re: Replace Diesel with electric engine

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My electric motor is 48-120 volt 22Kw continuous 55Kw peak water cooled motor. Running at about 12Kw. Remember they have super torque.
Ok what motor?
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Old 22-03-2022, 13:28   #468
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Re: Replace Diesel with electric engine

SailingWisdom uses an ElectricYacht system. Specifically a double motor system. Both motors are wired the same, one is not reverse wired, the regen is handled with electronics. 2 motors are used to achieve the desired power. EY has fewer motors to stock that way and the individual motors are smaller and lighter which makes shipping and installation easier.

At 4.0kt Wisdim uses 4800W, at 3.6kt 3200W.
At 3.0kt I would expect the use 1500W or less.
Their Morgan 45 is about 1/2’ longer on the waterline, 1’ wider and 3,000 lighter than a Formosa 41.
I could see the Formosa making 2.5kt using 1,000W.
Keep us apprised ToeRail.
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Old 22-03-2022, 13:31   #469
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Re: Replace Diesel with electric engine

Quote:
Originally Posted by Adelie View Post
SailingWisdom uses an ElectricYacht system. Specifically a double motor system. Both motors are wired the same, one is not reverse wired, the regen is handled with electronics. 2 motors are used to achieve the desired power. EY has fewer motors to stock that way and the individual motors are smaller and lighter which makes shipping and installation easier.

At 4.0kt Wisdim uses 4800W, at 3.6kt 3200W.
At 3.0kt I would expect the use 1500W or less.
Their Morgan 45 is about 1/2’ longer on the waterline, 1’ wider and 3,000 lighter than a Formosa 41.
I could see the Formosa making 2.5kt using 1,000W.
Keep us apprised ToeRail.
Thank you for the info I never really paid much attention to that part of their channel.
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Old 22-03-2022, 13:41   #470
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Re: Replace Diesel with electric engine

I’ve made a point of recording info about speed, wattage and boat type where people indicate they have directly measured those values. Most of the info I have is for Boats 32-36’ and 800-1200W will get you 3.0kt for direct or belt drive.

27’ & 45’ are the shortest and longest and I don’t have a lot of data points for either.
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Old 22-03-2022, 13:47   #471
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Re: Replace Diesel with electric engine

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Originally Posted by Adelie View Post
I’ve made a point of recording info about speed, wattage and boat type where people indicate they have directly measured those values. Most of the info I have is for Boats 32-36’ and 800-1200W will get you 3.0kt for direct or belt drive.

27’ & 45’ are the shortest and longest and I don’t have a lot of data points for either.
So it seems I could get 3 or so with my 29 but now when battery energy density meets up we will have something .

Till then 100 plus hours at 4 knots and refill the battery in 15 to 20 minutes . Diesel still is top . But battery is catching up .
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Old 22-03-2022, 15:58   #472
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Re: Replace Diesel with electric engine

Right now I believe you you could build an electric drive that would push a 35’ boat at 3.0kt using 600-800W.
Current systems using the existing prop and shaft in 32’-36’ boats use 900-1200W at 3.0kt.

The cutlass bearing and shaft seal are a significant source of friction and the normal prop at 14” +/- is geared for a lot of power with a limited clearance to the hull with 6-8kt as the target speed.

To get much better efficiency you need lower drive line friction, slower design speed and a really big slow turning prop.

You can get 32” model aircraft props in carbon fiber. That diameter pretty much means an outboard installation. You get several thing from larger slower turning props. Reduce friction due to lower flow speed over the foil. Also high aspect ratio so less induced drag. Just like a sail plane, long skinny wings at lower speeds.

With an outboard you can use looser seals with less friction but water will get into the works so you will have additional viscous friction so I don’t have a sense Of how much friction can be eliminated.

For a motor I would use a 1800-3000W gocart motor with a PWM controller.

Given the large diameter prop, and the need to have the tip 9-12” below the surface at rest and the motor carried several feet above the water surface that means total motor height will be around 6’ or 7’. It will probably need to be stored in place with everything pulled straight up into a protective cover.

Acceleration will be poor and top speed will be somewhere in the range of 3-4kt. At some rotational speed blade erosion due to particles in the water will start to be a problem. Until I get my act together and actually try it I don’t know at what speed erosion will be a problem.

For bigger boats props with more blades to absorb more power is the solution. There will be a little efficiency loss due to increased blade count but the alternative is a bigger diameter prop which comes with a different set of trade offs. There are 32” carbon fiber props with up to 5 blades available.
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Old 22-03-2022, 20:16   #473
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Re: Replace Diesel with electric engine

Those numbers for Wisdom are average
50 amps 3,5knts at 48 v
100 amps 4 knts at 48v
250 amps 5 to 6 knts at 48v
My motor will run 250 amps continuous but will drain the batteries around 30 minutes
But you have the speed if needed for emergencies where an engine rev would be needed
They can stop a boat very fast
Max RPM is only 2400 RPM's,

Can program it to 6000 but the controller cant handle the amps, would need a bigger controller
But its all measured in watts for controllers, a higher voltage controller has less amps
A higher amp controller has less volts, but power is equal
There are old tales told about efficiency that just are not true, not real world, and not used
There is also Sailing Uma, Beau and Brandy Sailing, a Golden motor conversion on youtube
Also Sailing Spoondrifter, and a few others. Solar tech with
Sailing s/v Delos,and battery tech with DIY Solar with Will Prowse and a few others.
If anyone is interested
48volts at 250 amps continuous is how I get a 12KW running power of the motor(max long time)
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Old 22-03-2022, 20:28   #474
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Re: Replace Diesel with electric engine

motor is me1616 by motenergy
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Old 22-03-2022, 20:30   #475
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Re: Replace Diesel with electric engine

Quote:
Originally Posted by toerail View Post
Those numbers for Wisdom are average
50 amps 3,5knts at 48 v
100 amps 4 knts at 48v
250 amps 5 to 6 knts at 48v
My motor will run 250 amps continuous but will drain the batteries around 30 minutes
But you have the speed if needed for emergencies where an engine rev would be needed
They can stop a boat very fast
Max RPM is only 2400 RPM's,

Can program it to 6000 but the controller cant handle the amps, would need a bigger controller
But its all measured in watts for controllers, a higher voltage controller has less amps
A higher amp controller has less volts, but power is equal
There are old tales told about efficiency that just are not true, not real world, and not used
There is also Sailing Uma, Beau and Brandy Sailing, a Golden motor conversion on youtube
Also Sailing Spoondrifter, and a few others. Solar tech with
Sailing s/v Delos,and battery tech with DIY Solar with Will Prowse and a few others.
If anyone is interested
48volts at 250 amps continuous is how I get a 12KW running power of the motor(max long time)
If I read your numbers correctly there is no 20 amp 5 hour and 2.5 knots .
And a 100ah even lfp not good to use all 100 ah. 75 to 80 yes but not all 100. Not for longevity of the battery that is .

Now a serious tech issue . If your motor is running a constant 250 amps that is a 2.5C discharge rate and those server rack batteries are not designed for that discharge rate.
You may want to rethink your paradigms a bit to compensate.

BTW running your stock perkins at 1/3 throttle is approx the same as your proposed 12kw electric motor
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Old 22-03-2022, 22:10   #476
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Re: Replace Diesel with electric engine

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A 48volt 100ah bank would push my boat at 2.7 knts at 20 amps for 5 hrs. In daylight solar on a good day would do that. Increase the bank with 2 more and you can run 15 hrs off batteries alone at that speed. Smaller boat would go longer. etc.

All the guys are talking about an electric motor of 10-20 kW. That is 417 Amps. Am I missing something? with 20A one will be able to run a blower....
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Old 22-03-2022, 23:02   #477
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Re: Replace Diesel with electric engine

ok
An electric motor is rated in a power range for its maximum power
Mine is like 20Kw to 55Kw, 48 volts(36 oddball) to 96 volts(120v oddball) x their 550 amps max gets Kw. For instance 36volts x 550 amps gets about 20Kw and 96 volts x 550 amps gets about 55Kw
This is power consumed,

I dont know why when the motor only takes 250 amps at any voltage

Now that Kw is the rating of your battery bank voltage and max amps
Now you want to know how many amps it takes to spin the prop at a given rpm to give you a set speed in knts
Thats what the 20 amps at 2.7 knts is. And x 48volts equals 960 watts
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Old 22-03-2022, 23:10   #478
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Re: Replace Diesel with electric engine

Wisdom mentioned he got 18 amps at peak sun from his 1Kw solar panels, he doesnt use articulating panels.
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Old 23-03-2022, 02:58   #479
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Re: Replace Diesel with electric engine

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All the guys are talking about an electric motor of 10-20 kW. That is 417 Amps. Am I missing something? with 20A one will be able to run a blower....
I believe it's the change in voltage.

When everyone is talking 12v, you can cheat and talk amps but when you start introducing non-standard voltages, it's much better to talk in watts.

So 20amps at 48v, is 960w, no where close to 10-20kw...and I would hope whoever is designing the system either wires it to the full motor rating or they derate the controls, so it can't burn up the wiring system...because yeah, 400amps will generate a lot of heat.
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Old 23-03-2022, 02:59   #480
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Re: Replace Diesel with electric engine

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Originally Posted by toerail View Post
A 48volt 100ah bank would push my boat at 2.7 knts at 20 amps for 5 hrs. In daylight solar on a good day would do that. Increase the bank with 2 more and you can run 15 hrs off batteries alone at that speed. Smaller boat would go longer. etc.
Except no battery manufacturer recommends using 100%. So if you stop at 20% charge, that's only 4 hours.

How big is your solar array, to provide 8kwh, you will need around 2000w of solar but if you are sending some/all of the solar directly to the motors, probably more like 3000-3500w of solar.

That's a lot of solar to fit on a Formosa 41 especially considering shading losses...and I assume you want to run the house loads off the solar power, so maybe 4500w of solar.

This also doesn't take into account battery storage losses.

All for 2.7kts cruise speed which in 15...oops...13 hours will net you about 35nm...which you could likely do with the original diesel in about 5 hours not pushing hard.

This is before we even get into the fact that 20amps at 48v is only around 1.2hp, so any kind of adverse conditions and you are no longer making 2.7kt.

If you purely use it to get in and out of harbor, electric is viable. If you actually use the motor while cruising, not so much.
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