Small video of yesterdays 12S12P test run.
We used custom impellers in the jets, and they were causing cavitation with the higher RPM.
Because of this and the board being very slippery, standing on the board was difficult.
We will add EVA mats later when done testing.
Unfortunately the phone inside the battery box did not get a GPS lock (due to being from carbon?), so no speed data (for now).
Hi Kian, happy to see you improving your jetboard, do you mind showing us your custom impellers?
Edit: watched the video, your board is now crazy fast!
Hi Eden,
I am not sure if I am allowed to show them but will ask Mark (person who makes the jets / impellers) if it is okay.
Basically the blades of the impellers overlaps a little bit.
We did some static test last year and they work great (for us) till a certain RPM, but above the RPM and they start to cavitate.
As we are now running 12S we go way above that RPM
It could be that the jets start to steal water from each other, so we need to do some more testing with this.
For now we are back to the old impellers.
Soon more.
I don’t think they steal water from each other, I think your ‘cheese piece’ as Mark calls them, are not deep enough in the water, happened to me on my board too, as you speed up and (planing speed) your board rises up and you end up relying mostly on water suction so I believe it’s the time your pumps intake/priming inefficiently, try to design your intake slightly different to scoop more water similar to commercial jetboards:
Thank you for your input Eden.
Yes we were thinking ‘scoops’ too.
However when we did the static test last summer (board not moving) we had the same problem.
So… The board was not moving, and this cavitating was only with the ‘custom’ impellers.
Will be doing more testing soon.
Cavitation during static test will arrive at a lower rpm than during real word test to some point , I added a plate on my Jetski couple years ago , worked great , you will loose some top speed but the gain is nice , may be easier to add on your board something like this than redo the all intake
Thank you Alexandre. That does look like a good way to fix the cavitation.
We will 1st test again with the other impellers. If the problem is not fixed we will try to make a plate like you suggested. We might even be able to intergrade the fins into this.
More info will follow.
Yep, I didn’t mean he should redo everything, a 3D printed scoop/grate around the intake should be enough for testing.
The 3d printed way is how I understood it.
Only way to do it the other way is by rebuilding the board, or remounting the jet box.
We have already made a design for the 3d printed way incase the other impellers do not work.
That’s great, please share some pictures! 
Time for a small update.
Finally we managed to get some more testing done with our DIY jet board.
The ESC’s in this run are set to 70% power output.
We still have some cavitation problems, but only in rough conditions.
Another small issue is with the BMS FET’s heating up too much, however this should be an easy fix.
Or… See the longer version here:
Beautiful, congrats, I like the carbon look!
Thank you. It was a great learning experience.
From designing the board, shaping it, and glassing it.
One thing I really love now is working with composite materials!
80mm m.k. jet
Esc 400a
13s8p battery 60amp bms
Sss 360kv motor
Board weight 23kg
Rider weight 80kg
7mph roughly
You guys are definitely missing something. Both top brands jet boards I have in mind are in the range of 7.5k - 9k rpm with 100-110mm diameter impeller and they have around 100kg+ thrust. I tried to hold the board still, impossible with that much thrust.
The motors you guys are using don’t have enough torque for this application. I can tell you guys you would need at least 15Nm of torque with the above rpm to get the impeller pushing 100kg…
Sure, lightweight riders might be able to push the board to 40kmh with half the torque, but the calculations I posted above are proven in the field…
Sounds to me that you need more RPM’s
Maybe a 600kv motor will fix this.
We tested two 360kv motors in our board, and this was not getting the RPM’s we wanted.
We are now back to the two 600kv motors, and getting around 50KG of thrust (jets are only 53mm.)
(feels like way more when holding the board by hand.!)
RPM’s we are doing are now around the 15.000.
Pulling amps when running W.O.T. is around 300 amp total!
Do you have some more info about the “80mm m.k. jet”??
Rpm motor depends on the rider weight. You might fly at 40kmh while heavier riders won’t with the same setup.
I would consider using a torqstar motor at 8500rpm and a 110mm jet.
looks nice. If you can, try a bigger (KV’s) motor.
You will need to change the ESC too. a 60 amp BMS will not handle a bigger motor.
Is the flier 400a esc not enough power?
I got full throttle and it didn’t trip bms? Only time I’ve had issues with it tripping bms was when I try to make it to go 100% from 0 with smaller battery
