Propulsion System - Motors, Gears, etc

Aloha PacMeister! Would you mind sharing the link to the V2 Duckt? I cannot locate it.

Mahalo :sunglasses:

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i glad you find the problem, so you are changing the gearbox and the motor as well? the motor is ok?


I am going to take the motor and the gearbox to metal machine shop and see if they can put in a pin or a sleeve between the motor shaft and the gearbox. Hopefully that fixes it.

This is what I am using for my setup. I am using 360kv with 4:1 Parker gearhead. I am stilling tweaking the couplers to avoid slipping. Will let you know.

I also had trouble finding it, I don’t think he posted it yet.

@MauiMan, @Filip, I just updated the post and added a rev3 CAD assembly with all Fusion components including current duct and prop. I also exported the rev3 STLs. Good luck :slight_smile:

Thank you very much!

Thank you! I will let you know how my testing goes.

Hi @pacificmeister,

I printed out the V2 duct and got a new collar for the gearhead. I am waiting on the Ride engine hydrofoil track box so no water test yet. In the meantime,

What do you think of the speed of the propellers?

Great. Sounds similar to my setup, you should get foiling with that no problem. Where are you planing to take it out? Kahului Harbour or straight into the surf? Good luck.

Great I hope my new collar holds up.

I usually kite at Oldman’s beach, but I jetsurf north of Kihei ik Maalaaea bay becuase it is deeper water so I dont hit the reef. We’ll see what happens when I hit the water and get some resistance on the system.

Thanks for the pointers.

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I installed the reducer neugart 5: 1 but it heats up after only 5 to 10 minutes
what do you use to lower the temperature

Hi Giloris, I can’t measure the heat on my setup and I don’t do anything about it. Just keep my fingers crossed. Unfortunately we stress these planetary gears quite hard and they won’t last forever. You could design an aluminum sealmount piece that fits snug and transfers the heat out.

Does anyone know what type of grease or oil that could be used to lower the heat and extend the life of the gearbox?
I assume that the low backlash is not an advantage for the way that we use these gearboxes?

Low backlash is something we look for in machinery applications, for example a CNC machine. Even if you used the reverse, a little backlash would not be noticible.

Hey guys just starting my build but what do we think of this motor:


I use a similar outrunner, a 6374 200kv from another maufacturer. Outrunners are difficult too cool in a watertight environment, unless you go Direct drive outrunner with direct water cooling . I did not see many builds with an outrunner and my jet is still underpowered.

Hi Guys!

It would be interesting to know (at least I’m curious) which one has more future in these designs,
A) a relatively large diameter propeller, which of course will provide more prop efficiency, but also more drag because it needs to be ducted, also needs to have some protection before, and after the prop, also it will need a low RPM / high torque drive, so either reduction gearbox is required, or a low KV motor, which means increased I^2 x R losses,
B) a jet pump drive, which has the disadvantage of a lower efficiency impeller, spinning at quite high RPM, but a more “safe to use” rotor/stator assembly, and has the advantage of a neat, thin design.

I’m new to this forum, but it seems to me, you are stuck with some RC brushless motors. Maybe, if you could come to consensus on the required power, RPM, torque, voltage, diameter, length specifications, I could be able to get someone to design a highly optimized motor, which then could be mass produced, thus putting it into a reasonable price range.

Any thoughts?


Nice idea, could you give us a link to such motor which is better designed than RC brushless motor? Why do you think low Kv means increased ohmic loss?


I could not give you a link to such a motor datasheet, due to intellectual property reasons, but I have seen som of the work done by my friend, who designs PMSM motors, ranging from a couple of Nmm torque at some thousand RPMs, to the couple of hundred Nm torque, at the speed of around 10k RPMs…
…About low KV: As far as I know, a DC/BLDC/PMSM motor is pretty much the same from the behaviour point of view. The same motor produces torque (ideally, as if commuted well, and no field weakening is applied, or as RC guys call it, timing) proportionally with current flowing in the windings, and generates backEMF against the voltage trying to generate the current, proportionally with RPM. Consequently, If you want more torque (once again, in the same motor), you will need more turns of windings, and in the same volume, this means longer wire, with less diameter. Of course there are “tricks” just like changing winding pattern, or pole/slot count, but that is not the same motor.