Direct drive outrunner with direct water cooling

@vefoil that is definitely a serious concern! I knew I should make a duct for safety but you’ve motivated me to do it for the next ride…

It just didn’t have enough power to get me up on the plane still… Do you think that a larger surfboard that is more buoyant can make a lot of difference? The small foam board I’m using is submerged when I lay on it in the water.

@Antonbit The motors I’m using are extremely cheap at $60AUD each. I don’t think that the motors you linked would have enough torque at 320KV, my 190KV motors are still to high…

But if it could work with cheap ESC’s like you linked that would be good for lowering the cost!

Great to hear! I cant stomach the thought of guts getting sliced open or private parts - shark bait! lol

With direct drive setups the proper foil and board it 50% of the setup, if those two are not matched for low thrust setup then your toast. A planning hull is critical, the wider the back of your board the better, and flatter the bottom as well. a surfboard that tapers in at the back won’t work with the direct drive.

Direct/Jet drives are safer and sleeker with much less drag than a large prop and duct, but the trade-off is a much wider board, little longer, and a flat bottom.

What size is your board, and what foil, also what is your weight?

And yes, if your RPMS are maxing out then you have left over torque to use and a 3 blade should provide more thrust.

1 Like

@VeFoil The board I was testing on is a small foam surfboard, which i was testing with dual motors as you saw above but no foil. My new build which I’ve started already is with the parts below. The only thing I’m concerned about is the size and buoyancy of the surfboard that I’m using.

My board is a 6’2 surfboard, it has a flat bottom and is made of fibreglass but certainly isn’t very buoyant…

And the foil is from aliexpress, its a nice big wing and a few others on here are using it i think…

I weight 72KG

Do you think I need a better board?

Hi Jake, I use also an old surfboard it’s even smaller and I am 10kg heavier. To start it’s a little harder (power and skills) but once your up on the foil it has less inertia.
One of the drawbacks is the lack of space for big batteries

I have no doubt you will need a board that is 28+" wide, and it must be wide at the back to get planing, that board will plow the tail through the water and prevent you from getting up on foil most likely. But if you have not tried it, test it out first, your only 72kg, thats lot lighter than me 115kg :slight_smile:

Thanks @Clarin , that’s good to know. Do you know roughly how much power it takes to get up onto the plane?

I guess the only advantage is less inertia.

Cheers @VeFoil, appreciate the help. Ill give it a try, hopefully within the next few days. If it doesn’t work, do you think a SUP would be a good type of board to mount the foil to?

Here is the post where you can see my power curve, I guess the other advantages of a smaller board is less aerodynamic drag, less weight, more nimble, tighter curve, and easier to transport. (My next one will be 150cm and 50cm long and will have more volume for more battery)

1 Like

NP, yes SUP is what that foil is meant for and if you cut an SUP back off so its wide and shorter, you should be rocking!

1 Like

Thanks @VeFoil and @Clarin

making some progress now, Just have to design a duct for each propeller :confused:

Motor stators epoxied:


Nice job on motor epoxy!!!

1 Like

Its amazing how these simple ideas grow. Thanks for your further development, this was intention. Although i think the coating shown is too thick.

Do you have a video and or supplies required to do this you could share? I’m working on another type of project and it requires an out-runner in water and I would like to do this as well.

Hi im a new user to the this forum and have built an electric skateboard about a year ago, This is probably not the right place to ask this as its off topic but would anyone mind pointing me in the right direction. I do not have a 3d printer or parts to machine so it would need to all be buyable. Thanks

Take a look at Pacificmeister’s design and read around the forum a bit to get going. The efoil scene is less developed than electric skateboards, so you will be on your own somewhat when it comes to exactly what you’re trying to accomplish. Good luck!

Im completing an efoil builders kit where everything is plug-n-play from parts, to propulsion system, to board, to waterproof remote control at VeFoil


Yesterday I tried to run my Hydrofoil surf. So far it went wel, but i could not het enough speed to het On the foil. Some how maybe my prop size is to big, so im going to trim it down a bit. Im running a turnigy rotomax, direct drive under water, with an toro beast 200A esc, On 8s lfp 45ah… from the sound it felt like the esc was hitting its 200A limit Or it felt out of sync?
This is a car esc, and maybe not suitable for running a multipole outrunner. So I need to find a suitable Esc that could handle 8s and at leest 200A+ that I could connect to my heat sync. The bottom of the board is a big aluminium surface. Had annybody have a God experience with a God price/quality esc? That can handle multipole motor 200A+?

Batterij: 12 Cell ~ 14 Cell / 44.4V ~ 51.8V
RPM: 195kv
Max stroom: 150A
Watts: 6600w
Geen belasting stroom: 44V / 4.8a
Inwendige weerstand: 0,013 Ohm
Gewicht: 1916g
Diameter van de schacht: 10mm
Winding: 8T
Stator Pole: 24
Motor Pole: 20
Stator Diameter: 101
Lamineren Dikte: 0.2mm
Voorgestelde ESC: 200A 14S Compatible

1 Like

What motor do you have?

i love your built!
i run 8S as well , hitting 32km/h and counting 25H (40mm inrunner with gear 1/6 so 130KV), my esc “recorded” for hard take off with 90kg and 1250 fornt wing:
165A with solas propeller 190mm diameter and 6 pitch
205A with FR propeller 135mm diameter and high pitch (9?)

so you can hit easly 200A with your motor, because high torque before rpm, big propeller with high pitch

what i would do.: cut yes, try the 350P10 2 blades torqeedo or solas plastic

as the esc i am happy so far with hiefi, i will go to 12S to get the amp down (after lipo burst on voltage sag) , good review on this one , and good price , i order one of this; you will have to make your own cooling