My Experience with EV – Part 6A Motor Mount Mods

As of my last post, my plan was to mount my electric motor below the floorboards to open up the cabin layout. This would allow me to better utilize the space within the boat for living aboard. This dream was FOILED!

Here is what happened.

After I mounted the sprocket on the motor and bolted it to the CV joint I quickly learned that the motor would not fit below the floorboard! Earlier when I had tried it, I did not have to motor attached to the CV joint, and once I did, the motor would no longer fit. I tried rotating it, I tried moving it around, no dice. There was one angle that would allow it to fit, but it proposed several more issues that I was not willing to deal with.

  1. The motor would not be aligned well, this would translate to excess wear on both the motor and the CV joint and excessive noise.
  2. The poles of the motor would be VERY close to the floorboard, being that the floorboard was intended to be aluminum plate, that could translate to a 48V electric floor.
  3. The mount would be a challenge to fabricate, and the motor would be very challenging to install and remove. Having worked on several older cars thinking “why did they put that there, don’t they know it may need servicing one day?”  made me realize that It was not a good idea.

Back to the drawing board, this was frustrating, I had a self imposed timeline that I would not meet, and one last Duck Dodge that I would not make prior to leaving for a work trip to Australia for a month. But the ever optamist that I am, I quickly changed gears and came up with a new solution. The motor would now mount below the entry steps, and spin the propeller shaft by way of pulleys.

There were a few advantages to this setup, so all in all, it was not a loss.

  1. The battery poles were no longer close to the floorboards, and did not create a case for an electric floor.
  2. The mount would be easier to create, and would allow for some flexibility in assembly/removal.
  3. Now that I was no longer running a direct drive, I could play with pulley sizes to get a more ideal RPM at the propeller (though there will be loss in the system due to the belt).
  4. The motor would no longer be in the bilge – no more risk of submerged electric system.
  5. It would force me to learn another piece of the boat that I was scared of – propeller shaft packing.

The new plan:

I was going to fiberglass in some wood pieces between the floor and the hull vertically. To these mounts I would bolt two short pieces of angle, and across the top, I would bolt a piece of aluminum plate. In the plate, I would use bolts to make adjustable motor mounts so that I could easily tighten/loosen the belt and properly align the motor.

In order to make it work, I would first have to remove the transmission coupling from the propeller shaft so that I could put the new pulley directly on the propeller shaft. According to the forums, this can be a daunting task that may include cutting my propeller shaft!

I decided to start with what I knew, I cut 4 pieces for wood to fit between the floor and the hull and sealed the wood with epoxy. After the epoxy cured, I glued the wood to the hull and the floor, and screwed them to the floor.

Once the glue cured, I came back across with fiberglass matte to make the mounts rock solid. Pro tip – cut the fiberglass matte to manageable sizes, and wet it out on wax paper before applying to the area. A good reference for this is a video from the folks as Sailing Uma found here. It is very important to completely wet out the fiberglass matte. Fiberglass has this uncanny ability to wick moisture into the entire matte from a single strand of dry exposed fiberglass. Since this mount is below the floorboards, there is a slight chance of moisture, and I don’t want my motor breaking the mounts free.

Now, onto that propeller shaft. Before I started disassembly, I had to first educate myself on how they work, how they are assembled, and what I needed to watch out for.

YouTube turned out to be the best source of information, and this video turned out to be very useful in giving me an understanding on how/why they work, and how they are assembled. The forums were filled with horror stories about how difficult the are to disassemble and how most people just end up cutting the shaft and starting fresh – an option I was not too keen on.

After some search, I came up with a plan to remove the coupling. First step was to remove the set screws on the caliper and loosen the hose clamp backup. Then I would pry the shaft apart from the CV joint and insert and socket between the coupling and the CV joint. I would then tighten the coupling and CV join back together and the socket would press the shaft out. This process worked like a charm, but was a serious PITA and took a couple hours, a video of my efforts can be found here. After getting the coupling off, I sanded off the rust and slid the new pulley on the shaft and reassembled. The reassembly was straightforward, but light sanding was required on both the shaft and the coupling.

Back to the motor mounts, I went on a hunt for some aluminum angle and plate. I ended up in South Seattle at a scrap yard where I was able to buy the angle cut to size along with the plate for a less than $10! Unfortunately, the angle was steel and the plate was aluminum, left to their own devices the two dissimilar metals would undergo galvanic corrosion, essentially eating each-other away. To combat this, a coat of paint and epoxy was used.

I took extra precaution against the corrosion, and cut up an old mouse pad to place between the two metals as a “rubber spacer.”

I screwed the steel angle to the fiberglass mounts I made with 8 hearty stainless steel screws and the mount was rock solid. After the plate was bolted down, I set the motor on top to mock up the mount and size the belt I would need.

I needed a 28″ B series belt, which I sourced from O’Riely for $11. The end result looked something like this:

 

Woohooo! The motor is mounted, time to make those electric connections!

Follow along for My Experience with EV – Part 6B for the end result of the motor mounts.

 

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