Electric Boat Motor

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  #1  
Old 11-17-10, 04:22 PM
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Electric Boat Motor

I would like to use an electric motor to replace the existing 10hp motor on my boat. I am trying to figure out whether it should be AC or DC and what equipment I would need coming from batteries as the power source. I am all ears.
 
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Old 11-17-10, 05:09 PM
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Visit the MinnKota site.

I don't know if you can get 10HP out of an electric and I don't know of any AC electric boat motors. High thrust DC motors typically require lots of battery reserve. Deep cycle batteries for this application can be very pricey.

My last electric was bow mount, 52 lbs thrust that would move a 18 foot boat at a fair pace but nothing like a 10 HP outboard. I had a 2 battery 24VDC system and on high speed I doubt if the batteries would have lasted more than an hour.
 
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Old 11-17-10, 06:09 PM
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This is going to be a retrofit. I am going to take the electric motor and attach it to the lower unit of gas powered unit. So, which motor would be better for variable speeds, reverse etc.
 
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Old 11-17-10, 06:59 PM
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That's kind of like asking what kind of fish tastes best. You are going to need to know what kind of shaft you need to connect the motor to the lower unit before selecting a motor at the very least.

I suggest that you do an Internet search using the term dc electric motor and check the surplus sites. You will want a 24 volt motor made for continuous duty. You will need to use two 12 volt or four 6 volt batteries wired in series. Deep cycle batteries are a must.
 
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Old 11-17-10, 07:07 PM
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C'mon guys. Read these posts really carefully and draw a picture in your minds. He is proposing attaching an electric motor to the foot of a former motor. It ain't gonna work, period, no how.
 
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Old 11-18-10, 05:18 AM
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A 1/2 HP 12VDC motor will draw about 40 amps. In theory a single deep cycle could run it for 3 hours, but 2 is more likely in the real world. Some of that HP will be used to overcome the power transfer friction in the drive unit caused by the transmission and u-joints. It could work, but at a max RPM of 1700 or so you could probably row the boat faster.
 
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Old 11-18-10, 05:27 AM
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Welcome to our forums!

You could replace a gas boat motor with electric but you need to carefully research the power available when a motor runs off a battery as compared to running a motor off gasoline.

The amount of energy in a gallon of gas that weighs about six pounds compared to the energy in a battery that weighs over fifty pounds is many times more.
In other words, if you were to even find a electric motor that could replace a 10 HP outboard the number of batteries you would need to equal the run time of say five gallons of gas would blow your mind!

Not a practical idea I'm afraid.
 
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Old 11-18-10, 05:12 PM
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This is what I am talking about. http://groups.yahoo.com/group/electr...unt=20&dir=asc. I just would like to know whether I should use an AC or DC motor.
 
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Old 11-18-10, 05:24 PM
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Sorry, only those who are members of Yahoo Groups can see your link.

Got anywhere else you can see this?
 
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Old 11-18-10, 07:15 PM
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You will find it extremely difficult (read, impossible) to get alternating current from a battery. You could, connect an inverter between the battery and the motor but that will be more cost, more weight and more inefficiencies.

Chandler, he COULD do it if he has a long enough shaft to keep the motor out of the water AND has a relatively water tight motor. May not be practical but that isn't what he asked.
 
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Old 11-18-10, 07:58 PM
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Furd, he said he wanted to put the electric motor on the foot of the gas motor unit. The foot is under water all the time. Is this keeping the motor out of the water? You're right it ain't practical.
 
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Old 11-18-10, 08:18 PM
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Just trust me on that one I have see someone did manged to get a forklift drive motor on the lower leg of outboard unit but as far for battery system it need 36 volts just keep it running.

I know there is couple legit electric outboard manufacters around here.

Here one I know it is a true designed unit.

Motors

Merci.
Marc
 
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Old 11-18-10, 09:24 PM
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It seems to me rather then try to rebuild a gasoline outboard it would make more sense to build an inboard hybrid diesel electric with batteries.
 
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Old 11-19-10, 05:13 AM
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Or one that separated the hydrogen from the surrounding water and used it as a fuel to power a turbine that produced endless electricity to run the fork lift motor Marc mentioned. You could fish all day, but the boat would be as big as the Queen Mary.
 
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Old 11-19-10, 06:12 PM
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Originally Posted by chandler View Post
Furd, he said he wanted to put the electric motor on the foot of the gas motor unit. The foot is under water all the time. Is this keeping the motor out of the water? You're right it ain't practical.
No, he said he wanted to mount it on the "lower unit" of an outboard. I've been away from outboards for far too long but back in my day the "lower unit" was everything below the engine itself. The top of the lower unit was above water, usually a minimum of six inches above water.

I don't know whether or not his ten-horsepower engine is a single cylinder or two-cylinder model but when making comparisons between electric motors and single-cylinder gasoline engines it is common use about 2/3 of the gasoline engine's rated horsepower to determine the necessary horsepower of the electric motor. Nor do I know what the gear ratio is between his engine output and the propeller might be. It may be a problem matching a motor to the same speed although using a series-wound motor should be okay. He may need to use a different pitch propeller and finding one of the proper pitch might be difficult.

We don't have any idea of what performance he is expecting from this Rube Goldberg setup. If all he wants to do is use the lower unit from a crapped out engine to get the boat to move it might be okay but if he wants the boat to move like it did with the gasoline engine he will be sorely disappointed. It is often fun to experiment with a bunch of junk to see what you can do but re-inventing the wheel is rarely economically advantageous.
 
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Old 11-19-10, 06:36 PM
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OK, so you say he is ditching the internal combustion part and using the shaft part which is out of water. Hey, makes sense to me!!
Still think separating the hydrogen was a good idea.
 
  #17  
Old 11-19-10, 06:50 PM
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If you have a boat large enough to house the atomic power station to supply the electricity to dissociate the hydrogen from the seawater you would be better off using a magnetohydrodynamic drive. (Do a Google. )
 
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Old 11-19-10, 11:46 PM
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Originally Posted by Furd View Post
If you have a boat large enough to house the atomic power station to supply the electricity to dissociate the hydrogen from the seawater you would be better off using a magnetohydrodynamic drive. (Do a Google. )
Now don't start that on Red October vessel in movie LOL but seriously I know someone will have a idea how to combat it and belive or not the techogly really improve alot and can use the AC motor with modfied VSD now that talking power there but may have to boost the battery voltage up a bit something like 150 to 300 volt range then it will work very well but the drawback is battery weight. unless you have a bunch of cordless tool battery hook up.

Merci.
Marc
 
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