# NooB with an EV boat plan!



## mizlplix (May 1, 2011)

Plan on some fairly big motors. I am afraid that golf cart size is way too small.

I would use two 11" DC motors. the props would be fairly appropriate rpm wise.

My bigger concern is battery type and placement.

What are your range/speed expectations?

Miz


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## Duncan (Dec 8, 2008)

Hi Meangreen

If you stay within your "hull speed" you will only need about 10hp so relatively small motors will be fine,

The efficiency goes up with prop diameter so see what is the largest props you can fit, - you may need to gear the motors down

11 inch motors would be massive overkill!


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## mizlplix (May 1, 2011)

I like overkill. I would use 11HV motors. 

8mph would get boring quickly.

Miz


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## meangreen (Oct 19, 2011)

My lake has over 600 miles of shoreline but I only want to cruise about 6 miles of it.
I plan on running a 72V deep cycle bank per motor and only use 85 percent of the motors recommended output. Just to stay on the safe side. I have room for as many batteries needed and plan on using a wind gen plus a diy 6.5hpX 3 alternator charging method while at stop.

Oh and my props are a little over 13". Plenty for cruising I would suspect.


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## Duncan (Dec 8, 2008)

Hi Mizlplix

I like overkill as well - but - 
a planing boat uses so much power that electric is not really viable

sticking to hull speed reduces the power by a factor of 20??

Hi Meangreen 
13 inches sounds big - big is good!


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## mizlplix (May 1, 2011)

It sounds like a nice day cruiser. Some small motors will do nicely then. 

Have you considered some water thrusters to assist with low speed turning? It can be an electric system and added later. An electric powered water pump and simple water jets at 4 corners controlled by electric valves. 

Take pics and share with us.

Miz


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## Anaerin (Feb 4, 2009)

You'll only need one controller. You can connect 2 (DC) motors to one controller in series or parallel, depending on if you have high voltage or high amperage available (Series for a high voltage pack/controller, Parallel for a high amperage pack/controller). Given that you'll be turning the props at around 3700-4200 RPM, which is pretty much mid-high range for a DC electric motor (They top out at 5500 RPM or so) you don't need a transmission to change speeds. A pair of 7" motors (or 9" if the torque needed is just too big) in series with a 244V pack would do very nicely indeed.


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## meangreen (Oct 19, 2011)

Hi Anaerobic,

I can use one controller for two motors? Can I put one motor in forward and the other in reverse at the same time? Low speed maneuvering is better controlled with the props and not the rudders. Would I be able to use two potboxes to control both motors with one controller?

Thanks


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## Anaerin (Feb 4, 2009)

meangreen said:


> Hi Anaerobic,


Interesting spell check correction. 


meangreen said:


> I can use one controller for two motors? Can I put one motor in forward and the other in reverse at the same time? Low speed maneuvering is better controlled with the props and not the rudders. Would I be able to use two potboxes to control both motors with one controller?


No, but you could use reversing contactors to switch one (or both) motors off or reverse them. So you'd have the option of:

```
Port | S'board
-----+--------
On   | On
Rev  | Rev
Off  | Off
Off  | On
On   | Off
Rev  | On
On   | Rev
Rev  | Off
Off  | Rev
```


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## meangreen (Oct 19, 2011)

Is there anyway I can operate those contactors from the helm station?

What I would prefer is using parts from golf carts as long as the motors I plan on using will work with the controllers. Im looking at running a 72v bank at 400 amps. (Per motor).


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## MidEastBatteries (Mar 10, 2011)

ofc, Reversing contactors can be done from anywhere you can get wires from.

You basically have 1 wire coming the battery going to 3 position toggle switch and then have 2 out wires. one is reverse, one is forward and one is left empty for "off", going back to the contactor and the other side of the contactor to the "battery negative".


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## DaveAK (Jun 28, 2009)

I know very little about golf carts, fork lifts or boats, so what follows is just the little information that I've picked up here and there.

Golf cart motors often have a female splined shaft and no face plate as they bolt directly to a differential. What's your budget for motors and controllers? There's quite a lot out there to choose from for a 72V system, and another issue would be that golf carts are often 48V and so you might need new controllers anyway.

What controls do you have at the helm? I'm guessing separate throttle controls for port and starboard motors? My preference would be to use the same set up and have a controller per motor operated by the existing throttle controls. Reversing the motors can either be done via reversing contactors, or you can go with sepex motors and controllers that typically have reverse built in. You'd need to figure out how to switch from forward to reverse, (or neutral), but either the contactor method or controller method simply requires low voltage wiring, so could be controlled from the helm.

I'm probably not going to be much help, but I really like the idea of a boat conversion so I'm going to keep an eye on this thread. Maybe one day I'll be able to convert a boat of my own. There's another boat conversion on here somewhere that you should check out.


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## Ektus (Feb 15, 2011)

DaveAK said:


> There's another boat conversion on here somewhere that you should check out.



There: http://www.diyelectriccar.com/forums/showthread.php/coupling-two-motors-jaw-couplingi-fw-55318.html


Regards
Ektus.


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## Wild (Aug 19, 2011)

Meangreen,
Let's float your boat with a better idea
http://www.aquawatt.at/en/inboard-propulsion-sytem.php

I will be converting boats and outboards in the future with a similar concept.


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## JRP3 (Mar 7, 2008)

I'm not sure the added cost of AC makes much sense in a boat that can't use regen. Since you already have the transmissions you might as well use them instead of paying for costly reversing contactors, plus you probably get some gear reduction as well, allowing the motors to spin faster at lower speeds. Plus you can also save money and use a single controller and still reverse the motors independently. You'll probably want to use forced air cooling to avoid heat issues http://www.diyelectriccar.com/forums/showthread.php/overheating-sepex-motor-controlleri-61756.html


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