I was thinking that yesterday when doing the air / water test… it’s time to redesign one 
I was about to get the front piece of the rotor out to see that it’s really flush on the inside.
did you measure the power when spinning it in water?
you’re not worried about lack of water circulation?
Get all surfaces as smooooth as possible. Even the stator notches can be filled without thermal worries, just leave a channel open so the wingdings get to water.
Spinning in Air: 162W
Spinning under Water full throttle: 825W
Spinning under Water half throttle: 250W
Test was with 44,4V only. (Battery wasnt charged up)
Stator and Magnets only covered with one coat epoxy. Nothing fancy, just KISS
There is a small gap, about 0,75mm, that should give enough waterflow. At least i hope so
so slight improvement compare to mine underwater… not sure if it’s the fit of the cap or may be some loss between my batteries and motor…
They say “Frischwasserpumpe” so ‘Fresh water pump’:
- do you think that sea water will be a pb ?
- is it a self-priming pump ?
Yes, selfpriming.
Freshwater… I guess seawater would be no problem. Inside it should be plastik anyway…
I’ve opened one up. It’s all plastic so salt water shouldn’t matter.
I guess anyway, everyone is using the same pump 
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Mine only switches on if the heatsink gets to 40 degrees. So it’s never switched on
Just make sure you flush it with fresh water from time to time to avoid salt to block it.
That’s an advice i didn’t follow and i think i’ll have to clean mine as my tubes looks ok, but the flow is getting lower…
I’m always surprise at the qty of salt I get at the bottom of my mast when the water slowly seeps out …
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OK, today was first test in a bucket…
and now: The motor sounds like a old barn door. Further Investigation: The big bearing seems to dissolve into rust fast as hell 
So i guess, i’ll have to wait for new bearings
Update next day
Now i cant turn the big bearing anymore.
Lucky me i already disassambled all bearings and gave them a final Destination:
RIP
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As I said before just remove this bearing and the cross part around it, the motor will run just fine and will win hundred watt in losses.
The can will still be maintened by the back bearing. We
I am afraid, that it will wobble and ruin my epoxy coating or even more 
Tested on mine, also smaller one such as 8072,63100 does not have this bearing and the motor is still rigid enough.
Maybe i’ll give it a try…
I was thinking about to replace one of the small bearings by a spacer, cause there is almost no radial load on it, only axial…
I think, there is no need to double up the bearing at the Propeller end