Very Slow Build from Sunshine Coast, Australia

Hello, this will be a very slow build due to time constraints, but I have made enough progress to start sharing and to ask advice…

So, this is a large jetboard for cruising out the back on the larger waves which aren’t breaking. It’s a big, buoyant aircraft carrier. I weigh 100kg and the total buoancy is 175kg. The board should weigh around 30kg. The important bits are;

2 x MHZ 58 jet units
2 x Scorpion HK-5035/760KV
2 x MakerX 300A VESCs
2 x 10S 12P battery packs

I am running dual systems as everything just gets too big (cables, VESCs, etc) with a single drive. As well, I like the reliability of two completely independent (almost) systems.

I will be running water cooling for the Scorpions and potentially for the battery packs.

Here is an overview of the design to date;

I will go into more detail on the design later.

I have just completed a test build of the electronics so that I can develop the sofwtare to run two systems from a single remote.

I have successfully run the VESC motor configuration tool on both motors and VESCs. The issue I have is that when I throttle up slowly, they run smoothly. If I throttle quickly, they vibrate badly as they ramp up. See video here;

Notice one of the VESCs goes into a fault mode.

Has anyone else faced this issue? I would imagine I now have to do some fine tuning in the motor configuration to smooth out the ramp up.

Any suggestions appreciated.

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Looking forward to your build.

To me the power wires to the vesc look really thin!
Will you be replacing them when done testing?


Yep, they are only temporary for the test bench. Will be running 4AWG from each battery.

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So, first battery coming together - only test leads on the main output at this stage. 10S10P with Molicell 42p. This should give me 42Ah and easily 300 amps. The internal resistance is claimed to be less than 15 mohms so, .15 ohms per strand @ 30 amps should generate less than 50W of heat at full power?

I am still debating whether I watercool the battery, but it appears that almost no one on the forum is doing that, so maybe I save myself a whole lot of complexity and hassle.

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First battery now working with telemetry.

I have just seen the conversation about long battery leads destroying ESCs! Whoops! Current design is to have the batteries at the front of the board. I’ll probably lengthen the motor leads and move the VESCs closer to the batteries.


Major milestone! Have fitted the two MHZ Jet58s. Next step is to wait until the sealant cures and then put the propiulsion box in the pool to make sure it doesn’t leak.

Not exactly sure how I am going to line the motors up perfectly to minimise wear on the coupling, but will work that out later.