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I've also decided to mount the motor straight to the drive, instaid of using the Leaf transmission. This will give me an rpm range more similar to that of a boat engine than if I use the transmission.
I read that planing boats usually utilize a higher prop rpm than deplacement boats, and by using the car transmission I think the prop rpm will be way too low even for a big ass prop. Like 700 rpm att full speed...
The tires of a Nissan Leaf are (in at least some years and trims) 205/55R16; their diameter means that they turn 836 revolutions per mile, so at 90 mph (1.6 miles per minute) they are turning over 1200 rpm... so that's the top speed of the Leaf's transmission output.

With about 7:1 reduction in the Leaf transmission, the motor is turning about 9000 rpm at that point. Do you really want either a 9000 rpm propeller or the motor using only a fraction of its speed range? What prop speed do you want?
 

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The motor would as mentioned be connected to the old inboard drive, with it's own internal gear box and reduction gear of usually about ~2:1. This reduction gear would give an engine with a peak of 7000 rpm a peak of 3500 prop rpm, and the Leaf motor with 10400 rpm would get a peak prop rpm of 5200 rpm. Now they're *allmost* in the same ballpark. :)
That makes more sense. There's no need to spin the Leaf motor all the way to its limit (and the inboard drive unit may not be able to reliably handle that speed anyway), but having the gear reduction to keep the Leaf motor in the speed range for maximum power over a wider range of operating conditions will help.

With the 2:1 reduction perhaps it would work fine to just use the bottom two-thirds of the Leaf motor's potential speed range with the same prop as would be used with a typical engine.

I'm actually a little interested in the propeller creep speed with and without the transmission. Do you know how many mph the creep is? :)
Not a clue, but that's something that could be found in boating forums if desired. With an electric motor not needing to idle, I don't understand why you would build in the minimum speed and resulting creep anyway.
 

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I decided to pair the motor up with six used Tesla 25V modules. This will give me 150V, 30 kWh.
Tesla Model S/X modules are nominally 22.5 V, not 25 V... just keep in mind that actual battery voltage varies with the state of charge, and 25 V is the fully-charged state. Nearly discharged is about 18 V.
 
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