It has been a while since I have written or even thought about my electric lobster boat, Eleccentricity. It has become an ordinary part of my summer life and has presented few problems or challenges. I did replace the motor last summer when I figured out that salt was corroding the inside of the old motor…the Mars ME 0909 permanent magnet DC motor. This motor has a fan which pulls air into the interior and consequently the bare steel was corroded until the bond with the permanent magnet was broken. The magnet was loose but not that loose. The main symptom was a worrisome vibration. I bought and installed a similar but totally enclosed motor, ME 1007.
Out of the blue, I recently received an email from someone in Norway who had read my posts about my boat and had built his own. His boat is similar in length and uses the same motor (ME 0909), has 4 AGM instead of 6 “wet” lead acid batteries and operates at 24 volts DC instead of my 36 volts. The length is the same–eighteen feet–but the beam (width) is narrower, at just under 5 feet, compared to over 6 feet on mine.
His boat steers with a tiller and rudder rather than a wheel and pivoting outboard. His prop is an inboard, with a shaft connected to the motor with a belt, and his motor is within a sound-proofed ventilated enclosure. He uses his boat on fresh water, and has also added solar panels, totaling 308 watts. He reports satisfaction with his setup and plans on building another.
I am envious of what must be very quiet operation. My motor is on top of a converted outboard and therefore makes more noise, although much less than an infernal combustion engine. Normal conversation is possible. His sound level must be a whisper. He has made a 50 KM (31 mile) trip and has had power to spare. Our speed VS watts numbers are surprisingly similar. We both can travel at about 5-3/4 MPH using 1000 watts. We both use only solar energy to charge our battery bank and can claim to use zero fossil fuels.
I have often wished I could convert Eleccentricity to an inboard and achieve the same quiet, but I would have to allow easy access to the prop, which is always getting fouled up with seaweed. Summertime around here brings large mats of loose rockweed just waiting for my prop. I added a skeg under it a few years ago, and that has helped, but I will always need to have it within reaching distance. The skeg is not an ideal afterthought. It has improved tracking but the metal struts set up an annoying vibration at higher speeds. And they collect rockweed too!
Perhaps with enough people around the world building eighteen foot electric boats we will arrive at the perfect design. Thanks to my friend in Norway for getting us all a little closer.