Propulsion System - Motors, Gears, etc

The engine is too slow 6-7 km / h on 12v, 500w

Thank you. This result is no surprise to me if the motor is still in original condition. I own similar trolling motors (up to 1450 W, for use on boats). The usual rpm and the propeller pitch prevent a higher speed. But I think, a different setup could be successful, because there are types in the needed power range.

1 Like

I have wanted to try this!
Could you try changing out the propeller and getting a little more horsepower out of it?


I opened the engine to see if there was a gearbox but there was none. I can try at higher voltage. What propeller would you offer?

Pacificmeister has some CAD files on good Propellers Pacificmeister Build Info and CAD Sources

I think this one might work too.

1 Like

Hello! Do you think how much thrust has a jet pump with a 40mm propeller? 1200w will they suffice?

You need at least 2x 50mm 2000w each imho

1 Like

probsbly like 8-10 kg max

1 Like

Seen this 120kv. Waterproof.


Looking at the PM-build; what do you do to prevent waterleaks between the lipseals and the printed plastic part called “Seal mount”? Seems to me that the somewhat rough 3d-printed surface will seal badly against the outer side of the lipseals? Do you sand it? Silicone it? What do you say…

1 Like

Available from Aliexpress for 350USD+ 40USD shipping -
not bad, eliminates need for almost everything else, except mast clamp and - if you want it - Prop-guard.
On the other hand it has 75mm diameter (more with mast-clamp) so it will have higher drag and it will probably need 14s and up; last not least it is heavier than Pacificmeister’s design.
Still, I like it :slight_smile:

Definitely interested in hearing feedback if anyone tests one of these motors.

This is funny:
Max Amps:

I want to use the 220A of course.
Just a minute, 0.0895 Ohms - oh no, that makes 220A * 220A * 0.0895 = 4331 Watt of ohmic powerlosses. That will not work for more than 10 seconds.
So i have to go back to 50V 80A. 80 * 80 * 0.0895 = 572W
So i can put in 4000W, getting 3438W (or less) out.
An outrunner has half the resistance and thereby half of the ohmic powerloss, 40% less area for induced drag and wheighs less than the half. And it can be cooled much better. It also has less than half of the length.


Super interesting. I think it reads on the ad mp105 posted that diameter is 56mm ?

Here is the inside with the bearing

Got version 3 of my MHz jet connect.


Looks great! Will you share the 3d model?

1 Like

Here’s the 3d model of the jet connector and the motor mount (56104 in 56.5/60mm aluminum tube):


Link doesn’t work for me?

Very Nice job @Kappertz