Updated data

I realized I never posted new performance data. As mentioned in an earlier post, the knotmeter was off considerably. Below are the new figures. This time around I also made sure the boat had come up to speed for a full minute or two before taking a reading.

KNOTS  /  TIME REMAINING  /  AMPS  /  VOLTS  /  RPM

2.4  /  14.6  /  6  /  50  /  720
2.8  /  8.5  /  10  /  50  /  920
3.7  /  3.6  /  23  /  49  /  1170
4  /  2.7  /  29  /  49  /  1290
4.6  /  1.6  /  47  /  48  /  1460
5  /  1.2  /  63  /  48  /  1730

Scott at Electric Yacht is generally pleased with the performance, but said he expected a little better. I was hoping to get 5.5 to 6 knots, which is close to the boat's theoretical hull speed. Scott said this could be approached with a swap of one of the pulleys transferring power from the motor to the outdrive. I may opt to do it in the off season.

Electronics and waste

After a few more outings the motor (and myself) are settling in. Shortly after taking the new system online, I realized my instrument pods weren't working. Knotmeter is operational but that isn't powered--anemometer, wind indicator and depth gauge aren't showing any signs of life. I think it's a good thing that all are not working, indicating it could be a fuse or switch, which should be easier to diagnose than an individual wire. These were hit or miss in the seasons prior but last year I finally found the ground issue that was causing the problems. Then the motor went out. So now that the motor is working, the instruments are not. Nothing totally necessary at this point though.

Also, a few days ago I realized the head is having issues too. I much more like dealing with electricity. It's less dangerous.

Second outing

Took family out this evening--and recorded more data using two GPS units. Apparently my knotmeter is due for calibrating. Full throttle is giving me about 5 knots.

Shore power

I hooked up the shore power today to top off the battery bank. Even though the battery monitor was showing a 77% charge, the charger indicated somewhere in the low 30s. The manual states this number shouldn't be interpreted as progress to full charge, i.e. it could take 2 hours for it to go from 30% to 40%, then another 2 to get to 100%.

I didn't want to leave it unattended, so my wife, son and I rigged the boat and cleaned it while it was charging. It was plugged in for about 3-1/2 hours and it got up to about 85%. We had finished up everything we needed to do, so I disconnected the power cord and checked the battery monitor. It read 100%--confirming my suspicion that the monitor may not indicate the same charge as the battery charger.

Later,  I returned to the boat and hooked the charger up again. The readout indicated 85% and within 15 minutes it came up to a completed charge.

First outing - commissioning

I was getting anxious and finding someone who was willing to go out and help me with this was proving more difficult than I thought. May have been the way I posed it: "Hey, I just put a new motor in my boat, would you like to go out with me and test it out to see if it works? No, not sure how long it will take--probably depends how it works. Could be 45 minutes if it works great. Could be half a day if I have to tow it back. Why wouldn't it work? Oh I don't know. Because it's a boat. With an electric motor. Yes, electric. Um, 4 batteries. Yes, people have been using electricity to power boats for years--granted those people probably know a lot more about this sort of thing than I do."


Also, many of my friends' experiences on the boat have been tainted by outings on the boat when the old motor was in place (and semi-operational). Not many quite enjoy the smell of gasoline and exhaust from 2-cycle engines as I do. Something I may miss with the electric.


My wife and 6-year old son like things to go as planned when at sea. My son has very high expectations for the new motor after hearing about it for the last 9 months, and will probably be disappointed the new motor still won't make the boat go as fast as a Cigarette boat. So I thought I'd try the commissioning myself. 


I wasn't overly thrilled--but mostly due to the nail-biting experience of trying to make it through a shallow channel to get to open water. It takes me a few times to get to know where the channel is each year since the placement of the marker buoys isn't based on science or with any accuracy.

There was a 5-8 mph headwind heading out. Here are some readings I took:

KNOTS / RANGE / AMPS / VOLTS / RPM
w/ 5-8 MPH headwind


3.75 knots / .9hrs / 69A / 47V / 1770 RPM
3.5 knots / 1.2hrs / 54A / 47V / 1750 RPM
2.5 knots / 1.7hrs / 40A / 48V / 1530 RPM
2 knots / 6.4hrs / 12A / 49V / 1000 RPM


with tailwind
3.75 knots / .9hrs / 69A / 47V / 1750 RPM
2.5 knots / 1.6hrs / 43A / 48V / 1500 RPM
2 knots / 5.7hrs / 13A / 49V / 960 RPM

I made a slight adjustment then took these readings (still with tailwind)
2.5 knots / 2hrs / 35A / 48V / 1330 RPM

Overall, the motor ran smooth but seemed to be a little erratic at lower speeds (motor would rev up and down). Seems overly sensitive at certain spans. Upon return, battery level was reading 77%. In hindsight, I probably should have double checked my knotmeter with a GPS prior to the test.

I haven't been able to bounce these off Electric Yacht yet. I'll plan to share these with Scott next week to get his opinion. This one of the first few EY installations with the Sillette saildrive. The OEM engine was a 15hp, with effective hp probably closer to 10. I seem to be in that range with the new motor.


I still need to arrange my shore power connection. I have an outlet about 75 ft away from my slip, and due to nearby slips I may need to jog the boat down a few pilings to get the cord to reach. I'm really hoping the length doesn't affect the charger. It would be ironic to have to pull up to the gas dock to use the outlet there.

Dry run

Did a dry run motor test today at the boatyard. I can't tell you how nice it is to have a motor that doesn't require water to cool itself. It was impossible to start up the old motor while out of the water.

I had to make a few adjustments to the controller based on throttle orientation--other than that it worked as it should. Throttle seems very touchy but probably due to lack of resistance. I'll plan to launch and commission the motor sometime over the next few days. Hopefully minor things at this point like adjusting the power output, confirming voltage/RPMs, etc.

Batteries in place

I now have all the batteries in place, cables in order and ready for a dry run test of the system. Checked voltage of battery bank to make sure I don't fry anything before getting the rest of the components online. Hopefully will have some time tomorrow for the dry run.

Overall view showing motor compartment and lockers on the sides. Shot from fore facing aft.

Motor Controller Mounted

I had originally intended to mount the controller just forward of the motor on the bulkead in the engine compartment. It would've fit but wouldn't have had enough free area to access it. I've opted to install two aluminum rails in the engine compartment, suspending it about 7" above the floor. This arrangement was easy to put together and will provide more heat dissipation. I finished this up this afternoon, as well as running/connecting most of the non-battery cables (fuse/switch/contactor/controller/motor). I have installed 3 of the 4 batteries at this time but the devices to secure the batteries are all in place. I had to leave one out until I mounted the switch, fuse and contactor.

Photo below is prior to any "cable management." I'm hoping to clean things up a bit by securing them to the walls of the compartment. I'm also hopeful that I'll be able to keep the wiring in more of a line than a loop, which would likely cause magnetic interference with the compass on the pedestal (located just a few feet away).

The last photo shows the mounting of the fuse, switch and contactor on the bulkhead of the starboard battery compartment, formerly a gear locker underneath the cockpit seating. The cable extending from the right is going to come off the + on the battery bank. From right to left, we have the fuse, main switch, house battery switch (which also controlled the starting battery, now removed) and contactor/solenoid. From there a cable runs to the controller.

I'll be leaving town for a few days and I'm hoping to have the boat cleaned while I'm gone, leaving just a few more cable connections to make before doing a dry-run test on the motor during the week of July 11.










Engine compartment, or shall I say, motor compartment, with controller installed.

Controller with cover removed.

Forward bulkhead of starboard battery compartment. From right to left: fuse, main switch, house battery switch and contactor/solenoid. The thinner stray wire is from the charger which will connect to the + of the battery bank.

Mendota Boat Works

As mentioned in previous posts, Mendota Boat Works performed the install of the motor/outdrive. In addition, they've also permitted me to work on installing the rest of the system in their facility. This has been a huge favor. I wouldn't have the space at home to do this, nor would my neighbors appreciate it.

Mounting Battery Charger

Oddly enough, mounting the charger was probably one of the more difficult aspects I had to deal with. Despite its compact design and footprint, this thing weighs about 40 pounds. I wanted it close to one of my two AC outlets, and figured I would have to add an extension cord to the 12" cord it came with. The weight prevented my mounting it to a few surfaces which I thought may be good options but were constructed with thinner fiberglass. While it might have worked, I wouldn't want the thing ripping a hole on a vertical surface. Like many boats, Coincidence is very tight and has limited access behind panels from where you could add reinforcement.

I was fortunate to have a cubby space underneath the chart table. A microwave is usually positioned in front of it, so it wasn't used for much other than electrical access. Maybe 2 or 3 cubic feet. I found that I could rest the unit on the floor of the space, but I did have to raise it slightly to get the louvered door to close. I also had to be sure the wire could reach the negative post of the battery bank. It was a perfect fit. Probably the only one in this project!

Charger mounted in cubby space beneath chart table. Black area behind it is the hull, starboard side. AC outlet is just to the left.