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Old 28-12-2009, 19:20   #1
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Replacing Inboard Engine with Electric Motor

I have a prop shaft in my boat (with a propeller attached) that I can rotate from the inside. The engine was no good (single cylinder gas not working, its gone now) I was considering a trolling motor attached because it would be close to the right rpms, run on 12v, and give speed control (forward and reverse)


The prop shaft slightly leaks which is not ideal (haha). I managed I can wiggle it quite a bit (not rotate, but actually change the axis) and when I do, water comes it a lot more. For now it is tied in place with ropes to the position with minimal leakage (bilge pump runs 5 seconds a day) I can also push and pull the shaft in and out and it slides about an inch this way.

Is it possible to rebuild the stuffing box with the boat in the water? It might not need it, it seems like it leaks where the hose meets the hull. I wonder if I can just seal it there with epoxy.


Would it be ok to use a freshwater trolling motor (cheaper) since it is not in contact with water? Would it maybe screw up the motor because it wont cool as well? What other motors can I get for cheap enough? I think I want something really small (draws less than 50 amps at 12 volts)
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Old 28-12-2009, 19:31   #2
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A trolling motor was designed to turn the little tiny plastic prop that came with it, not your shaft, and bronze wheel.
If the stuffing box is leaking you can re-pack it without much fuss in the water, the shaft moving in and out is normal, but the up and down side to side isn't. It may spell a worn out cutlass bearing.
If the hose is in fact the culprit, you may need to replace the clamps, it's not uncommon for the perforated varity of hose clamps to remove themselves from these things. The epoxy would be a bad idea, the hose hase a finite lifespan and should be replaced........unless you really want to test out that foam filled compartment idea of yours.
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Old 28-12-2009, 19:35   #3
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there's always this too

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Old 29-12-2009, 00:42   #4
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A trolling motor is cooled by the water around it...if you bury it in your bilge it may get hot.
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Old 30-12-2009, 00:00   #5
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electric motors

My pops and I are currently changing out the shaft, shaft collar and propellar on our 27' watkins (damaged in hurricane Ike). It was overally pretty simple to pull out the shaft and the stuffing box and from what we can tell... restuffing the stuffing box is straightforward.

You could try tightening the stuffing box and it might stop your leak (squeezes the stuffing a bit which locks out the water better).

however, I would be very hesistant to do this in water. To change the stuffing you have to remove the shaft and you essentially get yourself a nice 1 inch hole in the bottom of the boat.... doesn't seem like a good idea.

As far as the electric engine... I too had the thought but with a golf cart engine ... has standard parts you can get anywhere, runs off a deep cycle battery, speed controllable... etc. I bet you could find a nice used one pretty cheap too.

The only problem is that to get any real range on batteries you'll need a lot of them ... and boy are they heavy! (1 12V deep cycle might get you about 30-60 mins of runtime at a nice slow speed)
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Old 30-12-2009, 00:03   #6
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electric engine conversion

Here you go: a nice how to convert to electric article.

Electric Sailboat
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Old 30-12-2009, 19:20   #7
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Fascinating article
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Old 30-12-2009, 19:38   #8
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Check out Practical Sailor- this months issue. I think you can get it free on their website. It has two companies that make smaller electric motors for the size of boat your describing.
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Old 30-12-2009, 21:01   #9
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I tried to see what the run-time was. When I clicked more all I got was a page of options????
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Old 30-12-2009, 21:19   #10
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You know, most golf carts will go all day. I just don't know how you'd reliably charge that sort of bank away from the dock.......it's possible, but just not cheap.
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Old 30-12-2009, 21:50   #11
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One of these days, I am going to play with my Honda Generator, a couple of batteries and a motor.
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