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[david48]

I have run my motors up  or the first time, no shafts just the bare motor . I ran them for 20 min, not much temp gain case felt just warm , thy were drawing 0.74 amps, one revved at 4006 rpm ,this was tested 4 times and that was consistent reading .  I used a12volts battery on both motors . The next motor was tested the same but it only reached 3862 rpm. Graupner spec reads 4000 rpm. I suppose if I had not done this test I would not have know , but I was trying to get reading to compare when the shafts were fitted and not lubed and lubed and amp draw . I am useing Action P 94 ESC will this even the revs differance or is there another fix. No radio gear set up yet .Maybe it is of no matter and I am reading to much into this .            Thank you all .
David, still building Fairmount Alpine

[inertia]

David
Less than 150 RPM (<4%) is precious little difference by the time you load up the props. Anyway, you have a rudder trim lever on your Tx to compensate for any slight tendency to turn one way. Unless you sail on perfectly still water with nil wind then there'll be more effect on the steering from the current and the breeze than you will get from this.
Dave M

[mudway]

Remember in a two motor set up, one motor will be going in reverse. Most motors produce less rpm in reverse than forward.
I've had 10 pole buhler motors which have nearly 10% difference in speed betwwen forwards & reverse. In the water that meant one prop was turning 200 rpm less than the other.

[david48]

Thank you for the help DM and Mudway ,thought there would be a easy answer . I have never sailed RC boats only built them for other people.
thanks again
David