For who try/have tried direct drive with outrunner


It is not hypocritical to defend and protect copyrights. This is a very important right in democratic regimes!

As I have already said, I am willing to carry out tests of various commercial and prototype propellers, I can advise on how to increase their efficiency, etc. And that is not hypocritical.


10k RPMs are not too high. For example, ship modellers sometimes use much higher speeds and do not need gearboxes either.

But who wants the transmission for the e-foil drive system, so let’s install it. It only gets acceleration and can use a simple and cheap propeller. Like a fisherman somewhere on a pond.


You want to test others prototypes (which may or may not be protected designs), which easily gives you the ability to copy or incorporate their designs into your own if they are good, but are not willing to share your designs even if protected by copyright. That there is hypocritical!
If your designs are copyrighted, surely you want as many people as possible selling and using the propellers. So either the design is not proven or it is not being manufactured for some reason. So when will the props be available?


It can be said that his e-foil does work but he does not have very good parameters. Very good parameters can not be obtained with the propeller used by ordinary vessels.


Model ships have very different characteristics to efoil as they are very lightweight and as a result need way less torque to start moving. You simply can’t use the same motor and propeller principles.
A higher RPM motor with smaller prop also uses way more power and as a result is less efficient. With an efoil you wan’t to reduce power requirements as much as possible in order to fly as long as possible and increase manoeuvrability.


It does not matter if the engine has a 100% (or 90% or 80%) torque at the e-foil start, but it depends on whether the propeller is properly optimized to drive the motor at 50% of nominal speed (or 60 % etc).


You were talking about the gearbox, and now you are talking about props? Mate, you’re all over the place. Show us one of your props genius.


Race model boats need very efficient ship bolts, so I have used them as an example.

The rule is: The smaller the propeller, the more (more precisely) it must be optimized!


As I have already said, I am willing to carry out tests of various commercial and prototype propellers, I can advise on how to increase their efficiency, etc.


I think this is a great idea but I’m not sure at the moment that 2,2 kW is enough to get on the foil. It probably is with a custom foil with a big surface area or a SUP foil for exemple.
From my point of view, Epoxying the motor is not the best way to go since it’s pretty hard to do it properly and a lot can go wrong throughout the process. Also, I personally am alergic to Epoxy resin (Discovered it while epoxying the board…).

So far I’m going on a 6384 motor, oil-cooled inside an aluminium tube sealed. The setup is really small in length ( 145mm long) and 70mm in diameter. The problem is the friction induces by the oil.

In my opinion, the best way to go would be to go for a smaller motor (maybe a 5070 one with 100Kv or lessif possible), mounted inside a 55mm tube… Cooling could probably be done via an aluminium plate linked both the the aluminium tube AND to the stator of the motor.
If cooling is OK, this setup would be super reliable, easy maintenance, low costs, low drag.


That’s what my shaft looks like…
It just come out slightly at the front, just enought to center the shaft.

Nothing comes out of the back, but i see your point regarding getting to the circlip.
I guess the washer/screw solution in a slightly enlarged center hole could work well.

@jakebarnhill1 on my motor, the piece that centers the big bearing in the rotor, would come into contact with the stator if you don’t remove the small screws first.
So without circlip, i’m afraid if the motor stops while you’re moving, the prop would be pulled the wrong way and you’d loose you stator if the interference above doesn’t happen on your motor…

@Bender isn’t that what happen to you? missing circlip?


Exactly, lost stator in the swimming pool, would have been worse in a lake ahaha


sure, i lost a rotor with propeller because of a wrongly mounted circlip at the first braking maneuver. Never found it again.


The problem with the circlip could be handled with a clamp ring or by having a watertight electric plug(s). The motor mounting plate screws are coming from the front and can be easily unscrewed. If we had a watertight plug inside the motor mount plate, the motor can be withdrawn straight to the back.
An alternative to watertight plug could be a watertight fixed coupling, but then you need to draw the flexible wires trough the mast to disassemble the circlip and maintain the bearings.
I have no experience with wires in mast, what do you think?


To be able to work on the motor without having to disconnect from the cables or move the cables inside the mast, i have a “service loop” that hides inside the pod on the other side of the mast from where the wires comes out of the mast… writing it, i realized how unclear it is… i’ll upload my post with a picture when i get home :slight_smile:


Maybe it works. The 63 has this boring scheme for mounting plate:

with a bolt circle diameter of 42.4mm
The 50 has

a bolt circle diameter of 38mm.
This is too tight to make a service loop with 6mm^2 cables i feel. There is simply no space in the pod.


Sorry, i cannot consider your special problems. Maybe you should wear gloves when dealing with epoxy. I barely had skin contact to epoxy, its ugly. Use Polyurethane or something else.

An oil filled can around the outrunner is too far away from direct cooling. It only opens new problems and solves none. You need a seal. You pollute the lake with oil. You pollute the oil with water. The motor pod is much bigger, inducing lots of drag. The aluminium tube causes eddy currents. The oil induces much more drag because of viscosity. I fear it will never work. Sorry to write this. I hope i can avoid great disappointment.


I agree, we are already having success with direct drives fully submerged in the water. Epoxy is not an issue, it can be applied by hand, then once it’s set just sand it back so it doesn’t interfere with the magnets.

The bearings should be no issue as well, the stock bearings on my motors are like new after hours of use over 6 weeks. They are not stainless steel either. I didn’t even oil after each use, i just filled the area between the bearings where the shaft slides through the centre of the motor with grease, and the small supply of grease keeps them rust free and running smooth. I have re-packed it once only.


I wasn’t asking for any sort of help regarding the epoxy (And obviously I wore gloves at all times), sorry if I didn’t express myself properly.

Also I’m using 100% vegetal oil that won’t damage anything AND am using dual Vring so that nothing can go out of the tube nor nothing can go in.
Regarding the induced drag, I did some measurments at maximum RPM (close to 4500 RPM):

  • Sealed mounted on, propeller spinning in the air: 530W
  • Same configuration but with the oil poured in: 700W.

If I’m not mistaken, being on the water won’t affect the added power induced by the oil.
In my opinion, both have pros and cons. Trial this weekend, I’ll let you know how it goes.


Awesome keen to see how it goes! Why don’t you try automatic transmission fluid? it is very thin and this is why some e-bikers use it in their hub motors to dissipate heat from the stator to the rotor to shed more heat. Ive done this on my bike hub motor and can confirm that it doesn’t damage the motor in any way apart from making everything inside oily.