Propellers and Ducts


I think this is surface prop, not good fully submersed.


I talked to guy who manufactures, he said she works in every way submerged, half term, anyway, I thought it more by the fact of trying to make direct drive without gearbox I believe it can work I will test, she has about 16 cm external diameter.


very nice! it would be great if that would work
To this kind of propellors have there own name?


I believe it can work, as @MaxMaker once said to try even if it fails, the propeller Thai name.


Still laughing…I myself felt the whiplash once she “engage”(d)…so glad to see this here because my first thought experiment desing used this exact principle

Those propellers are also available down to five inches


So you testeou and it didn’t work?


Prop question. Can we get practically same thrust with bigger diameter+ low pitch versus low diameter+huge pitch for the same amount of power, rpm and momentum? I get what is more efficient, what has bigger drag, cavitation posibility etc… but, is it possible?


Hey Guys,
I want to learn more about prop design, from the basics onwards. Found this read and was wandering (before I might buy it) if people know/use this one? Or perhaps some other literature suggestions?



Never though of one of the sea scooter props before, came across it by accident! Could be a good suit for an efoil given the shape




BLACK PROP (Diameter 150 mm, 6 inch PITCH, 12 mm axis) PRICE: 125€ free shipping EU

GOLD PROP (Diameter 150 mm, 7 inch PITCH, 12 mm axis) PRICE: 125€ free shipping EU


Surfbrazil I have to order it from the USA so I want to order a selection from 5 inch diamter right up to 8 or 9 inch…I understand they run as surface props but I want to motorize my old windsurfer so I apologize that I am not payng attention to some of the desing issues for the efoil builds


You may add the cheap (20 dollars ? ) metal 71/4 prop, sold as a Yamaha 3hp clone prop. We have 2 of them , untested, but I believe @Silvio has tested it successfully.


Thank you phil I really appreciate that. I also want to try the thai long tail props because they are almost 100% prop blade unlike the torqedoos that lose about 3.5 inches of diameter to the hub alone.


Where did you get the propeller?

Tell us where you can buy.

Do you have 3D CAD Data?


@borntosurf222, if I am not mistaking long tail props are for surface waters ( thus the specific shape).



NICE job with the prop !!

I was thinking it would be a good idea to have a roud bore in the prop and secure it with a shear pin. In this case, if the prop hits something the pin will break and not the prop, gear or motor.



Very clever and wise


Hi Phil
I gather they are or rather can be both

Some use a cover s hroud to keep it below the surface, others embrace the surface running and below is another weird aspect of a surface prop hiding in a virtual water hill…see below

I think the racing ones get a huge boost in efficiency by mimicking a racing prop and one blade is out of the ater all the time

Lastly, and this is so cool…even planing boats and boats about to plane produce a rather large “hill” of water immediately behind the boat which is actually ABOVE the static water level so the thai long tails exploits this dynamic “hill” and shove their prop in it to avoid hitting the bottom of the river in very shallow water

I think this is so cool because that stupid hill follows the boat in exactly ther ight place for the prop to exploit


Hi Aaron

Would you mind re-sharing your design? The dropbox link has expired.