Electric Motor Conversion

July 2014 was the month when the diesel finally died and I decided not to revive it anymore. That is when the decision was finalized to switch over to an electric system.

The old 3 cylinder Volvo Penta MD-17C was removed in small, easy to manage pieces and hauled off to the scrap yard. Then the engine bay was cleaned out and prepared for the new setup. The space that the Volvo occupied became the battery bank and extra storage (always a plus on a liveaboard boat). The space that the transmission occupied became the entire engine and drive unit!

The new motor weighs only 130lbs, and the 8 group 31 batteries weigh 536lbs. The total weight comes in around 140lbs less than the old engine and transmission, not counting the weight of diesel needed to push the boat along. Make sure you have davits on your boat so you can lift all this equipment up. The battery bank that we put in is 210Ah at 48V DC. The motor is a Quiet Torque 20KW motor from Electric Yacht (http://www.electricyacht.com/) which can push the boat up to hull speed for a short time. If I had opted for a larger battery bank, it could motor for longer times, but I only use the motor to get in and out of marinas, the rest is done by sail.

When we made our maiden voyage, we whispered away from the pier and quietly ghosted along. Under full throttle, you could hear the propeller cavitate because there was no other sound to mask it. 

Under sail, the propeller spins as water moves past it. This in turn rotates the motor which then generates electricity that charges the battery bank. As speed increases, so does the wattage (5kn: 40W, 6kn: 80W, 7kn: 200W). We can then use this electricity to keep things like the fridge and lights working on long passages.

I felt that this may be a bit of an undertaking to install myself so I opted to have it professionally installed. Bob Blood [(410)212-3336] did a beautiful installation.  Not only do I highly recommend him, I've hired him again to install the autopilot and I would certainly hire him again! I've even recommended him to my father when he needed some work done on his boat. He is an ABYC certified electrician and does beautiful work! 

Which motor would you prefer to have?

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