In the midst of Covid 2020, I decided it was time to replace our aging diesel engine with a new electric motor.   A friend of mine has had one in his lighter 30’ racing sailboat for over 10 years and I was always impressed with how quiet it was, easy to use and how responsive the torque was.  I was a little concerned about an electric motor’s ability to push our 10,000 pound Catalina 30, but after reading a few posts on various forums, I was more confident this would be a good transition.


I read a lot of posts by practical people pointing out that a diesel engine very efficiently converts petroleum into power with some very simple mechanisms.   Introducing an electric motor that needs a charger, possibly solar panels and/or wind turbines combined with a backup generator appears to be a more complicated system.  I disagree.  The diesel engine has over a dozen systems:  the cooling system is actually 3 systems – raw water intake, heat exchange, coolant flow; the electrical system involves a solenoid, a starter motor to start the diesel after the glow plugs have been warmed up.   Each of these requires maintenance, some of which is quite advanced.  See photographs below comparing the motors side-by-side.


We sail our cruiser all year round with weekly sunset races out of the marina for 6 months in the summer combined with weekend sails up and down the coast and several longer sails a year out to Catalina Island and beyond.   If most of your sailing is offshore, with the likelihood that you’ll be spending many days away from shore, then you’ll definitely need to have a mix of solar and wind power generators and have the flexibility of schedule to wait for power regeneration when there are prolonged periods of low or no wind.  The electric motor is ideal for us because on race nights and day sails out in the bay, we only use our motor to get in and out of the slip as well as power down the MDR channel.   The diesel engine is very bad at this as it never reaches operating temperature; so it is running very inefficiently and causes undue wear and tear.


The decision to replace our diesel with electric could not have been a better one for our situation.   The diesel engine is loud, the exhaust fumes can make you nauseous, the engine actively leaked oil into our bilge, several times a season it would not start when we really needed it to, requiring an annual unlimited tow insurance that was put to use at least once a month and, for us, the burning of petroleum to drive a sailboat just made very little sense.  Some will say that much of this is poor maintenance and I do not disagree.  The point is that the diesel requires far more maintenance than is possible by non-mechanical people such as myself while I could fairly easily install the entire electrical motor and even tighten the drive belt.


From our experience, installing the QuietTorque 10V Sport model was straight forward.  If you have some experience with wiring and are comfortable aligning a prop shaft to a motor, installing the motor can be done at your slip by you and a friend.   Since I had never aligned a motor, I hired a local wainwright to help with the motor mounting and installing the controller though in retrospect, I could have done the latter myself.   Electric Yacht has designed a very elegant mounting system that can adapt easily to a variety of layouts.


We installed 8 6V deep cycle AGM 250 Ah batteries to combine into a 48V system.   There are batteries you can get with 300+ Ah capacity that would get you more range, but we were already a little over our budget so stayed with the 250 Ah option.


Running the boat has been a game changer.   Being able to turn the key and be out of the slip (after our pre-departure checks) assured that the motor will work on the return without issue is such a relief.  Beyond that, we’ve already been twice to Catalina and are able to spend more time in the cabin without the deafening sound of the diesel or the odors from the exhaust.  It’s practically made a new boat out of our 35 year old cruiser.


Beyond these benefits, we’ll also never need to refill with diesel, change the oil and filters, remember to open the through hull or change the zincs in the heat exchange to name but a few of the regular maintenance activities needed for a diesel.






Still trying to figure out the best way to repurpose the old control center.  We’ve removed the panel and there is space back there to be able to store some emergency supplies or maybe our GPS?The controller designed and engineered by the Electric Yacht team is solidly engineered.  The battery monitor (attached at the bottom) is attached by an arm that can be flexibly mounted on top or below – we decided below to keep it out of the way.



With the engine removed, I got to cleaning out the housing.   I forgot to take a true before picture; this is roughly 50% of the way through cleaning up.   There was oil everywhere.With the oil largely cleaned up, I would have preferred to apply a nice fresh coat of paint but was on a tight schedule to get the motor installed in time for a planned trip to Catalina.  Here you also see the motor mounting shoes.  Solidly designed you can easily position them to mount the motor to align with the shaft.



The advantage of the Catalina’s design as compared to other models is that it offers relatively easy access to the engine compartment.  With the counter removed, we have full access to the engine, exhaust, and cooling system.The replacement motor is ½ the size of the diesel it replaced.  It installs easily on its mounts and aligns nicely with the shaft.  This is the only part that requires 2 people – getting the motor mounted on the shoes while preparing to align with the shaft.



And now we present the source of the energy for each propulsion option.  On the left we have a 15 gallon aluminum tank that could fail at any moment, leaking diesel into the bilge.  Diesel tanks can also get contaminated with silt and water if fixtures are not sealed tightly.  On the right we have the relatively simple electric motor along with 4 6V batteries connected in series.  These AGM enclosed batteries can last as long as 10 years under the right conditions.  We hope that in those years innovation in storage technology not only optimizes the recycling/reclaiming capabilities but possibly even significant new power storage options.



Following is an unfair comparison, but on the left is the old legacy wiring harness that became a rats nest.   On the right is the battery charger newly installed in the aft birth.  We did make a mistake in where we mounted it – its bottom rests on top of the aft birth cushion so we’ll have to cut a piece of the cushion out or move the charger.



I had wanted to draft up some precise schematics of the layout but ran out of steam.  Here are two drawings I made of the effort.  The first was a high level layout for my planning purposes and the second is a more detailed wiring diagram.