Sss 4092 electric hydrofoil for disbaled guy

Hey folks, planning my build and wanted to share my design with you.

Want to use the 40mm sss 4092 with 4300watts. As gearbox I planned to use a reisenauer 6:1 planetary reduction gear.

Fits perfectly on the 4092 motor with a flange. The gearbox will be screwed on the motor.

It all will fit in a 40mm innerdiameter aluminiumtube with an oil infill, means all the parts get cooled by oil and the aluminiumtube as heatsink.
Outer diameter 47,6mm of the aluminiumtube.

Wanted to use the 80mm diameter propeller as it should deliver enough power to the water.
8010 pitch

Means ESC, motor and gearbox is in the aluminiumtube.
The wings connect to the 750mm long aluminiumtube

what do you guys think about it? wanted to run the smaller motor a bit harder as due to the good cooling, around 6000watts max for short periods and 4500watts as continious.

btw, I’m disabled from the breast, so it will be the first electric hydrofoil for disabled people.
I’ll have to sit on it, any Ideas how to where to mount parts for good first try results?

The overall costs are so much smaller, that’s why I’m planning on a downscaled setup.

looking forrward for your opinions on this.

thanks alex


This is totally awesome!

My friend that has a c6/c7 injury would really like to join in on this adventure! He has asked us to build one that he can ride a couple of times, and we have been looking into it. He probably needs a bit more custom steering possibilities, but that could be arranged!

I think you could go for a slightly larger regular outboard engine prop, with a custom 3d-printed low drag propguard, this will probably be more efficient than the small 80mm, when you use a gearbox you should have enough torque to drive it.

Please let us know if you need any help with your design :slight_smile:

3000W should be more than enough to drive your setup! we use about 2000W in cruising 20km/h, with a smaller tube(less drag) the consumtion should be even lower. I would suggest using a large wing! :slight_smile:

I would consider having a separate fuselage, if you crash into something with both wings attached to your motor pod (if I understand you correctly), this will damage your entire system and could easily result in water ingress, instead of only damaging your fuselage and/or wings. This way your motor-pod tube can also be smaller.


I only have a remark concerning the oil cooling. How do you plan on handling the expansion of the oil with temperature and the resulting pressure inside your housing? I had some success with oil cooling a small outrunner, but dropped the idea because of the mess when changing parts and a lack of ideas concerning pressure buildup and sealing.

1 Like

Hey Hiorth and Flo thank you!

I really appreciate your opinions.
I own a good 3D Printer, a surfboard, the aluminum 90cm mast(i mean the part which combines surfboard and motorpod.
I also own the electronic stuffs needed for such a project, I once had a downhill bike with a mid drive in the 7kw range at her very last weeks… got stolen

A wing on ebay is about 300€ I think, printed wings are much cheaper and have a really good quality when glued together, so thow it away if it breaks…

Pod electronics will be sealed with a waterproof spray, if water breaks in.
God thanks all the people are achieving such massive improvements in science these days, I mean look at all the products you can buy and the technology behind it.

@Hiorth as you mentioned I will better use a 3d printed low drag propguard, with a 40mm holder and a 94mm prop, this will make it a super clean setup I think, thank you very much.
You guys will have to help me, since I’m new to CAD, trying my first models now for ex: the backseal with a holder for the prop and stuff but it’s a bit difficult :slight_smile:
maybe you guys might help me with a slightly modified file of the 94mm prop with a 40mm diameter attachment to the tube if I can’t work it out in the next few days, It would be very polite :slightly_smiling_face:

@Flo Do you think it is possible to use a overpressure ventile like this:überdruckventil+modellbau&client=firefox-b&dcr=0&source=lnms&tbm=shop&sa=X&ved=0ahUKEwiAxsfHnbXZAhUFZFAKHanRAKUQ_AUICygC&biw=1680&bih=872#spd=4558600405950384984

in combination with sunflower oil which is biodegradeable.
If I fill the aluminum tubes center with a lot of deadspace(so that not that much oil is needed just to realise the planetary gear cooling)
and this overpressure ventil attached to a chamber inside the tubes front for the expanded oil to catch and seperate it from the mainchamber, this should work I guess?
The electric motor is open, this means oil can go through there. front and back chamber are connected.

I will try it first with my monopod with wing Hiorth^^
I think it might not be that stupid to use the 40mm tube with 47,6 outher dia. It’s a very solid piece of metal, and as you suggested I will have to use larger size wings for a better lift at low speeds.
thanks again, a lot of needed experience from your side!

have an opinion on this or suggestions to realise the oil cooling without eventually pollute the water I’m inside that much if the motor pod should really be damaged and the seals break?

Hope we can stay in contact and your friend does continue the work on his work on the custom steering, would you tell me how you planned on doing this? I don’t know how good he accomodates to his situation…
tell him please that he’s not the only disabled efoiler :slight_smile:

If you have some questions on CAD I can maybe help you as I have done some projects in this realm.
With the overpressure valves I am not sure. I don‘t have much practical experience with shaft seals. Common shaft seals are specified for 0,5 bar max differential pressure. Therefore I asked about your ideas. If you release air in a hot state you might draw in water through the shaft seal while cooling and contaminate your oil.
Concerning edible oils: I don‘t remember if I used sunflower oil or corn seed oil(„Keimöl“), but it does decompose over time. This decomposition leaves a residue that can‘t be easily removed. I removed it recently from my motor with hot alcohol, but this in turn also slightly attaked the glue fixing the magnets. An environmentaly uncritical oil that does not decompose on its own in the motor would be nice :wink:

Does anyone know If there are stl files of the 94mm prop and guard?

Thanks alex

Edit @Flo maybe a ventile from a bicycle
I will work it out somehow, because I want the planetary gearbox oilcooled. Most concerns go for the planetary gearbox now

You can also cool the gearbox the “Hiorth-way”, just add aluminium segments around the round parts that just fit into the tube. Maybe add some thermal grease to get better contact between the gearbox and the segments as well as between the segments and the tube. Easier to assemble and disassemble.

1 Like

you are right lol

@Hiorth you could use gyro stabilizers for the custom steering :slight_smile:
but I think you have already a better idea?

Seems a bit easier to not use oil, the water cooling on the motor pod is pretty good, and as long as the heat is sufficiently transferred from the motor/esc/gearbox to the outer casing it should be fine. I also think the motor does not like to run in oil (friction). If you are doing it with a Long tube, you will get some air volum inside , that might pose a overpressure threat to the shaft seals (as with oil).

What type of ESC are you planning on using?

You should learn CAD, its not that hard. Use or Autodesk Fusion, both are free and easy to learn. At some point in this project you will need it anyhow! :wink: The parts you need are not that hard to construct.

Your mast is 90cm aluminium? It might be an Idea to cut it a bit down in length and re-thread the ends, the longer the mast the harder it is to ride, and the harder you will fall. We use 76cm Now, think we will go down to 65-70cm.

Was out riding today did almost the entire session sitting on the board with my feet skipping the water, its not that hard to sit on the board and control it only with your upper body! Gyro stabilizers would be nice to install, our plan would be to use a combination of software and mechanical stabilization (gyro could be one of these). But this is still down the line .

1 Like

Is sitting on it easier to learn?

nice project good luck , be carefull with the gearbox , the product is very nice BUT

1 Like

Hey Alex, no problem to ride disabled. Your build will work we tested similar long ago…
To ride seated don`t use a regular foil from kitesurfing. Those are not that easy to ride… We invented new sort of Foil Wing that is much more stabilizing itself and therefore very easy to ride for beginners or even disabled…
Will be available late summer;-)
If you have you build ready send us a pm, maybe we can arrange sending you a prototype wing;-)
Check this video for riding seated in a small harbour maze;-)

finally some advance on this topic :smiley:
thx to @hiorth for the stl files and all the effort he put in!

was a pain in the ass to find out how to print with abs,daaamn

have a question to the guys who can model parts. would you guys be that kind to remodel hiorths duct for me?

i need the mounting part being 46,7mm diameter with 40mm long 40mm “shaft” going into the aluminiumtube to mount.
made a little picture, hope you understand me. I’m just bad at cad, never learned it…

thx to all for all the stl files, especially hiorth sharing his work!

Edit: please make the aluminumtube a 50mm*5mm tube, 50mm outer dia and 40mm inner dia.
47,6mm is sold out…
Hope you guys can help me with this, or give instruction on how to modify hiorths file :slight_smile:
Good night lads!

edit 2 at deep night:
its warping a little, but the next print will be perfect, i adjustet z axis on the warping part, lowered the nozzle while printing.thats why the other edges won’t warp, just the start of the print.

I’llll take it as it is, if it gets worse tomorrow I’ll print a new one
this my friends is abs, a pain in the ass, but worth it. strong material

prop has to be printed again I think, lets see maybe i can sand it and balance it.
warping due to the bad first layer, abs is a pain in the ass. be sure to close the door while printing with abs, dont look to often how its going on, cold air may warp it lol

it’s not the first wing I am printing. 20% infill is enough, be sure to do at least 3 or better 4 vertical shells. the surface will be smooth af.

greats my friends

I put a rescue blanket over the printer, works like a charm for ASA.

But you could also just use PLA for the prop, ABS doesn’t give you any real benefits there.

Everyone struggling with ABS.

Enclosure 40- 60+ (parts are staying too soft to print).

Build Plate 110-120 degC + ABS Slurry (ABS with acetone, mix thin)

100% Infill ABS Parts with minimal warping.

If You don’t have an enclosure, just print with PET-G and leave your ABS worries (and smells) behind.

Bought 3 Kg of PETG, pics tomorrow.
Big hammer for the case printer won’t do as i command :triumph:

I have a little theoretical problem on prop size.
140mm prop has optimum range 1800-2500rpm hiorth says.
Best solution for me is 4500-6000rpm range. Has to do with gearbox and motor.
Would the prop have good results at this rpm range or do i have to downscale it?

Will use no duct at all, only a prop…
which diameter would be appropriate for those rpm’s?

thx alex

I am really doing this :crazy_face:
love the matrix style 3d print look on this:
front inlet has a little hole for the watercooling of the esc.
hope the waterpressure on the front will push that water through the watercoolingpipes und push it out on a sidehole I will drill in the aluminumtube.
still missing:
watercooled esc that fits into tubing, and the most important reduction planetary gear.
i will go with the 7:1 reduction, hope it’ll be enough.
things are not 100% worked out, will have to glue something here and there, but in theory I have good idea. Think i have done 60% of work now happy
for example i have to glue on an adapter for the shaftseal, behind the waterproof bearing… etc
still things to do but doable

designed some parts myself on cad software proud

which esc would you recommend?

120a cont, 760 burst


120a cont, 150 burst

will run on 6s, 20000mah battery.
both give me cont power of around 2660watts,
but the more expensive one is nicely programmable and gives burstpower far beyond need.
smooth start is needed i guess, to not harm the gearbox etc?
so I think I’ll go with the seaking esc?
you guys any suggestions on this?

1 Like

I am sorry to say but you really want to use 6s with a 40mm motor ? Why not a 600kv on 12s ?
I am using a 40mm tp power motor on 8s , more powerfull than sss and it is lacking of torque … Pulling hard in the battery pack in start , wires and plugs get hot …
I am not saying it is not possible but i think it makes things more difficult
My step up see 160% of max amp motor on start , running a esc 8s 220a and 280a burst
Esc can run hot , to hot and burn or to van burst on peak … The last number given can be tricky even the first one , it will not be the same with a 56mm motor because it has more torque …