My duct
Works well 
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Nice ! Did you notice a lot of extra drag ?
Haven’t tasted it yet
Great idea having the mount on the shaft. Interested to see how it performs. I had the same prop and it was a total pig, killed my battery in minutes and pulled so many amps I could fry an egg on it. Good luck, standing by for the good news.
I have 3 or 4 of those alu props from china, 5 and 8 pitch 7 1/4 and 7 1/2 diameter. Are those so bad ? I have no reference with other props and I am about to foil for the first time ever. What would you suggest ? c80100 130kv at 14s
If you have to choose one of yours, go for the smaller pitch and smaller diameter.
If you can print/finish it: that one from @foiledagain slightly modified: Fusion
It performed much better than my solas 7-1/4 x 6. i’m using a 80kv with 12s though…
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Hi Felix 
That is me calm. I design equipment for use in explosive environments, and one electrical fault and people burn to death.
Having said that donating a toe to science is no less noble.
What worries me is the risk of water entering and causing an unpredictable short, combine that with the likelyhood of the rider being IN THE WATER with their feet near the prop at the SAME TIME
A guy in England had a youtbue video demonstrating that and I believe it had rounded leading edges…they appeared rubberized like how they do toothbrush handles with hard plastic and a moulded in leading edge for us, for the toothbrush a section for superior grip or brushing the tongue
3D printers can do this now
To be perfectly honest I think (MYSELF INCLUDED) are so damn accustomed to seeing these open props with SO FAR no griveious bodilyharm we all stopped thinking they should only be A TEMPORARY solution
SO Felix, a large torqueedo prop at 1200 RPM, I TRIED THIS AT HOME WITH A HANDDRILL and it just PUSHES my hand away
I live in freaking Canada so we cannot get anything like what you guys buy here…well we can but dam it is so so expensive
I am in discussions with the durajet guy or I was and he was very helpful
I need to buy a single unit then downsize it and three d print a smaller version
I think but am not sure if he uses a completely conventional just very low RPM impeller
**I think for example a dead mans mechanical lock out that PHYSICALLY KEEPS the battery disconnected until the rider is ABOVE THE DAMN WATER and disconnects if the rider falls all is patentable but as of now I am the official inventor inspired by you so thank you as is the oversize propeller My company is Made2Order Safety/Security Solutions and we normally work on royalties but I would make this public domain if it means no one gets hurt in our nascent sport **
I took an arduous road to make the point and my idea or invention is not obvious to someone skilled in the trade because when I suggested it i got all the reasons why it was stupid this actually helps to secure a patent
I have prototyped this two ways, one using mate while wet desing connectors (not a fan to be honest) and the other a reed relay but mechanical to me is the way to go…so imagine the connection all cordless drills use but instead of connecting the batteries and motor it completes a circuit…I have one I ll take a pic if it not totally obvious?
Felix it took real guts to say I would prefer not to lose a toe, or finger any ideas guys…
it was irresponsible to say “you ll be good , my own kids do it all the time” that is like saying i drive drunk all the time and SO FAR SO GOOD 
I had tone but I was never angry just very frustrated that anyonew ould even think of seriously compromising safety, the sport and our image for a 5-30% boost in run time if something like an even larger oversize prop will completly eliminate anything but BRUISES, not exactly immune to bruizing in this sport…
cheersp
P Kay
Is this some type of joke? Patentable? This solution has existed here for just about as long as the forum has been around! Magnetic kill switches have been used by a couple of guys already.
The durajet is just a ducted fan running under the water. There really is no complexity involved in building one. Here is the impeller https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRTYPH7thh_wR7VqZy22Mz_PliTtjVS04D_kjjIshyRexYlcPGU
If you google around you can find a complete teardown of the unit.
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but I think that’s normal
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I second you on safety but what does “oversize” really mean ?
The flattering specifications come along with oversized prop:
From Torqueedo catalog: Motor power, prop diameter
2 blades, 1 HP, 200mm
2 blades, 1.5 to 3HP, 269 to 292mm
3 blades > 3HP, from 300mm
Looking forward to see this Torqueedo 300mm prop reduced to 170-180mm. You will note that the hub (boss ?) is flush with the motor for best efficiency. This model, if it was designed with accentuated winglets, should not be that dangerous since repelling approaching objects.
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Thanks,
I will try to print it with www.3dhubs.com
If we want this prop CNC in aluminium, we can get it for 73 euro per piece if we order 10 pcs.
Get instant CNC machining, 3D printing & sheet metal fabrication quotes - Hubs You can get an online quote.
And you have missed the point yet again
READ IT MORE CAREFULLY!
SoEFoil, thank you so much for understanding I want what is good for the sport and safety.
It is sincerely appreciated.
Thank you again,
Respectfully,
P Kay
SoEFoil
WE could just use the same prop as the waterwolf
at 1000-1200 rpm I gather but not sure it would just bruise you
Or we could spec a pitch for 35 knots and run it at 600-800 because our desired top speed is or will be half that
we cannot run this propeller (beside the fact those are for boat, but with the v10p350 you can get good results…)
- bigger propeller, it will be out of water or you need a least 1m mast
- low rpm : you need a gearbox like waterwolf, we don’t like very much gearbox and there is no motor on direct drive capable of running at this rpm with the needed torque
for safety the all thing i keep up with is a weak point in the system, like the propeller pin could break easly to minimise injury
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No, I get it, you are banging on about safety. But the topic of this discussion is a duct solution for the 80100 outrunner motor. The Durajet quite simply is not that solution.
The Waterwolf prop is the torqeedo prop. They just spin it at a higher RPM to get a faster speed.
To use the prop for efoil you would first need to cut it down (Alexandre explained why), and then spin it faster to get to the desired foil speed.
The ideal prop size is around 140mm (this allows foiling higher up while giving good power and speed), this is well proven by the commercial companies (FR started at around 180mm and went down to 140mm).
Now onto the actual topic. @Felixfoiler you will need a duct with around 6 struts to provide a sturdy structure and prevent vibration. The easiest way to do this would be to build the struts (5mm width) into the rear section of the mast clamp and then have the actual duct attach to the struts.
Thank you but I’m so frustrated how my prop duct turned out. Yesterday I tested it and I had lots of vibrations then It cam off and I tried without the prop and yes I flew for the first time on my foil.
That said i mounted it again on and I tired it again in the pool. To describe the feeling:
With duct: Slow lots of vibrations. It’s like cycling and breaking at the same time
Without duct: Free silent no vibrations fast.
BUT MY PERANTS IGNOR EVERY ARGUMENT TO DRIVE WITOUT IT. IM VERY CLOSE TO THROW AWAY MY PROJECT.
I am very frustrated now as my parents don’t listen to me. I know it’s dangerous and it can kill you but a car can too.
What size prop and duct are you using?
Hi,
I had similar problems on some prototypes with board bottom full of edges, screws heads etc it was the board behaviour was chaotic while touching the water.
i took your picture and circled in green the parts that may create some disturbance in your duct system.
Can you try to cut them at minimum length and use flat head screws ?
Also the wood part need to be given a more dynamic shape, or just replace it with a longer 3d printed part with water drop shape. And get those 2 top screws pass inside this part and also inside the fuselage.
