Okay, just to get back on topic, today I finally got the new motor & thrust bearing assembly installed. I just got it in there sort of rough and ready for now. I am expecting a piece of shaft and a roller chain coupling to arrive tomorrow morning. I did hook up the controller and roll the motor over, though. Whereas before I needed 162w to make 200RPM tied to the dock with the 2:1 reduction gear, and needed about 174w to make the same 200RPM with the 3:1 gearbox, I only needed 150w to make 200RPM in direct drive. I have some serious shaft alignment issues that I will address tomorrow so maybe I can shave another 5w or so off the power consumption at my 200 (prop) RPM benchmark. Throttle is touchy at low speed, and so I will be fiddling with the controller configuration. The ME0913 motor seems to do a good job swinging the 14" prop once I get over 200RPM or so. I did a full power test and briefly went over 100A into the controller... over 1000RPM and it was pushing a LOT of water across the harbor before it tripped out. Under 1A it does not start turning reliably. Anything over 2A is okay and I expect the sweet spot will be around 5A or 250-ish watts. Maybe I can get better low end performance after shaft alignment and controller reconfig. The shaft does turn fairly easily by hand but there is a bit of vibration. Actually, a lot of vibration, at a frequency equal to the RPM. It is an audible thump kind of sound at certain speeds. Smooths out nicely at full power.
So I am thinking the ideal gear ratio for my setup is probably around 1.5:1 to 1.7:1 discounting the gear losses. Not bad move, going direct. I might cut my spare prop down an inch and try it. I have been kind of dogmatic about swinging the biggest prop possible and making everything else work with the prop, but maybe that's not always the thing to do. The tail w roll it as wagging the dog. I thought I needed a reduction gear because I am turning a fairly large prop, but instead I will maybe try to optimize the prop for the motor. I did not take the boat out because of the shaft alignment issue but I know I will see better performance when I am not working with 100% slip.
So more knuckle busting tomorrow and then maybe a short sea trial. I need to figure out what I am going to use for a IR thermometer to monitor the motor case temp. It did not get hot to the touch in this evening's test session but it was a short one. I think one of my multimeters has an IR temp readout but if not then Harbor Freight here I come again.
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