Propellers and Ducts


In low speeds the thrust and efficiency is pretty good. I can foil at 1600w in apx 18kmh with 90kg rider, and a huge foil wing. In higher speeds it’s not very efficient, but it’s capable of about 35kmh. We lowered aoa from 5Degrees to 3 degrees and made the sections slightly thinner, which helped in higher speeds seemingly without decreasing low speed thrust/efficiency. Prop diameter=142mm

Prop distance to walls is important, we use 1mm (max2mm as our 3d printed is a bit off).



Wow, great info. I’m shooting for foiling at 1000-1200W(or less) but giving up top speed.
Going with a direct drive outrunner but otherwise its similar to your set up.
thanks for the info! much appreciated


Do you know the pitch of your prop? Is it the same prop PM used?


The prop is here. We designet it for 3d printing in PLA (thicker sections). Don’t know the exact pitch

Note that the duct profile aoa should be lower. Altho the one on instructables also works well.


I cant remember where I read it, but I read an article about Kort nozzles that said when a prop gets too close to the duct, cavitation increases. Counter intuitive, i know. Im going to give it about 3 mm clearance, still pretty close.


Hi Aaron,
i am very interessted to see your nozzle design.
would it be possible to send me the step-file?

thank you so much.



Despite I never seen it in my life, I’ve been asked for a sample design of a printable prop for 80100 direct drive motor. @DavidC is building one of this pod and could give it a shot, or at least evalutate if it can work and how to improve it. This is the link to the .stl file:

This have been designed in Javaprop and then scaled and made more real in Solidworks, I did it just for fun, so take it as an exercize…pheraps could help me getting better in prop design and revert this back on my Efoil.
Diameter 160mm, Pitch 132mm, I calculated little less than 4KW at 6500rpm, ideal speed of 25kt which is the speed I took as reference even for my geared pod.
In my opinion, the 80+mm hub cause some problem, I rather have liked to add a piece to close the motor tube smoothly reducing diameter, to get close to 50mm at the prop…or less.
For who’s alreadt running on that big motor, which prop size and specs are you using?


I have my motor cone tapered down to 50mm . this picture is of the version 1 but the outside diameters are the same in version 2