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Right after we bought the cottage in 1999, Carol decided we needed a pontoon boat. We could float around the lake, so? And we can drink adult beverages, now you're talking!
We found this old 24 footer, with a 1967 Evinrude engine. It didn't run very well, but we could fix that, we'll take it! After several seasons of trying to get the old gas motor to run right, we decided look for a new motor. While searching, we stumbled on a few electric powered poontons. Hey, that's for us! quiet & clean, so we decided to try electric. |
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As always, it's better to build than to buy. In the spring of 2004, we found a 3 HP, 36 volt, surplus electric motor. Now we can finally get the project rolling!
First thing we needed to do was lock the transmission in forward gear. We'll use the electronics to reverse the direction and control the speed. A simple part, with a spring and a screw where all that we needed to do this. |
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All of the gears and bearing looked to be in great shape, the seals seemed to be fine also.
The slide between the 2 gears selects the direction, with the spring loaded fingers (up a picture) holding it in place, forward gear is always selected. |
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We bought 2 identical sets of the 1.6:6 ratio surplus timing pulleys, I used the 2 smaller ones
in a 1:1 ratio. I made an extension for the drive shaft, and used a leftover bearing for support
I fabricated some aluminum mounting plates that bolt over the existing motor mount holes, along with some brackets to hold the motor and bearing. |
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It's a 36 volt motor, but I ran it on 12 volts to see what would happen. I used a trash can filled with water as
a test stand.
When I touched the wiring to my car battery, it threw water everywhere! IT WORKS! well it works on the stand, now it's time to see it push a boat. More soon! |
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There has been much debate at work about the project. 3 HP doesn't seem like much. To get some "real world" data, I dropped the motor on the boat and took it for a spin. I have to say, I was impressed at the speed of the boat with only 12 volts! I measured 11.76 volts at 44 amps, about 500 watts, or only 0.67 horsepower! |
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I did 2 data runs, measuring speed with GPS. Into the winds I ran 2.4 MPH at 44 amps. And with the wind, 3.0 MPH at 40 amps
I only got about 15 minutes of run time using an old dredge battery I expect better results with fresh batteries. |
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July 3rd 2004, Carol at the helm
I charged the old battery, and we took it around the whole lake, about an hour of run time! Even out on the big lake, wind and all, it ran great! |
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While we where out, Mike did some trolling, he hooked this nice 14" bass. |
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July 9rd 2004, It seemed the motor was loaded too much, so we changed some supports
and pulleys to give us a 1.6:1 ratio.
This allows the motor to spin faster, with less current, so we go the same speed!
We tried 12v, 18v, 24v and finally with 36 volts at 60 amps, we got up to 5.2 MPH! The boat really pushes a lot of water at 36 volts, but it's only 3HP. Around 24 volts & 45 amps, we cruise at 4.3 MPH, that seems to feel the best. |
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| Summer 2005: We added some electronics to control the motor. A simple microcontroller and some surplus power switches are all that are needed allow us to PWM the speed of the motor. We found some problems running the motor in reverse, with the gears locked in forward, so a gear shift mechanism needs to be built. Our GPS data for Current vs. Speed (at 36V)10A » 2.6 MPH 20A » 3.5 MPH 30A » 4.2 MPH 40A » 4.3 MPH 58A » 4.9 MPH Time is running short for this year, we'll be back at it in 2006. |
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July 2006, We built a new controller with a better micro, and devised a way to shift too!
This is our second prototype, we added the stepper motor for the gear shift. It turns the brass lead screw that shifts the transmission on command. The power section was cut from a broken GE golf cart drive, a contactor has been added to disconnect the battery |
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A side view of the new power stage and controller board.
Last year we had troubles getting into gear without turning the motor a bit first, so we also added a speed pickup (red cap in the center of the frame) to tell when the motor is turning. |
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For controls, we decided to keep it as stock looking as possible. To do that we machined off the gear shift section from the old handle set, and added an internal potentiometer on the throttle handle.
The throttle now controls both direction and speed, with a neutral detent added for feel. A LCD display communicates with the controller, and shows battery voltage, current, and a few other variables. |
| I added a battery box for the six 6 volt golf cart batteries. We bought a MinnKota 36V battery charger to keep them charged up. I think next year I'm going to move the contactor into the battery box, and layout a real circuit board for the controller. |  |
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We stripped the boat down to the deck and found that to be a bit rotten. We replaced the decking with 3/4" marine plywood and covered it with carpet from Lowe's. |
| The railings trapped thew water and debris on the deck, so we raised them up an inch. |  |
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The railing up for a fitting, with the seat that Carol recovered. |
| The start of my cable steering system. I wanted something clean and retro looking. |  |
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I moved the old steering gear and heavy cable under the deck. I use the smaller cables to turn the drum. The red spring is to keep the little cables tensioned. |
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A test fit to see how thing work.
More to come! |
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Story soon! |
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