Sorry how long needs the shaft to be ?
Base diameter 60mm?
That is perfect for my set up 
Hello
What’s the pitch of 3 blades? And 4?
3 blades black please
Aparrently there is such a thing as a safety propeller. The blades are rounded and the inventor can be seen sticking his arm and fingers in without any harm. Efficiency loss is claimed to be very small. This would allow us to safely remove the duct and have the efficiency too. I would try with some fruit and veggies before
trying with my body parts, but worth trying.
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There’s no real reason you couldn’t do this for DIY. I still think for commercial units they will sell with duct though as there less chance of people bruising and suing.
So far I haven’t seen a duct that keeps fingers and toes out. Even the jet designs have finger access to the prop. This may well be the safest option especially in combination with a simple/low drag prop guard.
Are you worried about getting your fingers in there? Or will you use them with “Noobs”?
Interesting, wonder how the prop performs with thick, round leading edge. Looks like reverse is not good for fingers, the trailing edge lookes sharp. Keep us posted, this is at least a better option than open regular outboard props.
With the duct we use now with 6 struts, its not possible to reach the prop(from the front) with fingers/toes as long as you use booties and keep your hands closed in the water.
But if they first get in there the result could be bad, as it will be “trapped” in there.
Hi Hiorth
Did you get much better efficiency from the rice nozzle? I like you duct design
what size is your prop? I’m looking at around 136mm. How much gap did you leave from prop to inside of duct. I see pictures of some and the gap is large which would cause big inefficiencies.
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.
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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?
bowi_k@hotmail.com
thank you so much.
Thomas
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:
80100-160/132mm
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?
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