S9tim's 80100 direct drive

Hi there are the coils coated with epoxy?

No coating on the coils. I only epoxied between the magnets.

The prop looks like it will cut you in half if you fall wrong. Does anybody have plans for covering it? Would be nice to hear about efficiencies lost with a duct on such a big prop.

Also, has anybody had success putting the 100kv APS 6384 PowerGlide motor with a duct on a foil board? I would love to know battery life because I am hoping to get up toward an hour of run time.

@s9tim awesome job!
I would like to ask you if you cut the motor shaft by yourself or you order the motor whit a custom shaft as you required?

I cut it myself with a dremel tool and cutoff wheel.

I made a hands free flush adapter for my APS 80100. I can hook it to the hose and it flushes the motor with fresh water while I tend to the batteries, etc. I will add the file tomorrow.


now that’s a cool idea.

do you spray the motor with wd40 or some form of oil to keep the bearings from rusting

I soak it in a bath of corrosion x about every 6 runs or so.

Usually ducts help to increase the efficiency. Helps to prevent tip vortexes. But if the ducts cross sectional area is too big you might get a lot of drag.

Amazing :slight_smile: What a topic.

Years ago I made all kind of electric outboard, jet surfboard, but also a direct drive surfboard.

It was a c80100 turnigy winded to 75KV, but always out of sync problems, the motor makes noise and vibrates, timing problems with the ESC. without a prop no problem. I tried all kind of controllers, also big 18 fet Ebike controllers.

So I ordered a Revolt 10 or 12 motor, ordered it with epoxied stator, expensive ceramic bearings, also same out of syns problems. Also with less pitch props. I gave up.

Now I still do have 1000 euro Lehner 7040 300kv motor water cooled from the Lampuga project and have a Neugart ple 80 1:8 so I can run about 1800 rpm prop speed for what I always believed was a good prop speed for outboards.

Since all efoil builders are around 4500 rpm. I could buy a Neugart ple 80 1:3. But now I see that you have great succes with a direct drive under water without loosing sync with the ESC that is really wonderful ! Maybe also much more silent. Since the torqeedo outboards make a lot of whining noise.

Also I want to build something that can reach about 40km/h and with your motor direct under water I think you can get so much power out of it.

About 3d printing I don’t know anything, I see many people here doing this, I tried a few free 3d drawing programs, I don’t have the skills I am afraid. Would you like to share your files ?

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Hi Louis , did you let go your project with twin 52mm mhz drive ?
40km/h would be hard to acheive but not impossible
Low rpm will mine big propeller …
With your motor you don’t want to try the mhz 64mm with vesc 75/300 for a jet board ?

Update: efoil build now right ?

Hi Alexandre, I had a 64mm MHZ Jet.

The thing is, I don’t want to TRY anything anymore :slight_smile: I want to build something now that already has proven itself. Our friend s9tim and others already made it so simple. I hope I can ride this ride with others this time.


Can you share the specs on that mhz 64mm jet.
What motor are you using and how much power?

Mhz 64mm jet, specs are at their website. Lehner motor liquid cooled 7040 winding 6 278 kv under load 11kw input i was running in the video. Forget that. Hydrofoil way more fun, speed, less sound, less power, less money, easier to build. Less batteries needed. And you fly and that is really cool :smile:

“I want to thank Matt and the others on here who have shared their files and did most of the design work.”

Where can i find these files? Somewhere online?

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that thread has all my parts scattered through :slight_smile:
the beginning is a test version, final version for new liquid force mast is later in the thread.

@Mat @s9tim,

How much current are you guys pulling at wide open throttle and how much does it take to cruise comfortably?

I just did a static test in a pool (board pushing against side of pool) with my 80100 setup and was pulling around 220A on12S at wide open throttle! I have my timing set to 30degrees to avoid sync issues (cant go lower without problems) and am running a flier 400A ESC. Wires in my battery box were getting really hot. Even the 8 gage wires going down the mast to the motor were almost 100C and for sure would have gotten much hotter if i ran it at that current for very long. Thats almost 10000W of power. This seems way too high right? I was running the two blade version of this prop (cant remember where i found the file but pretty sure it was from someone that was using the same motor). I have filled the magnet gaps in my rotor as well (although not nearly as nice as some of the rotors i have seen on here).

Any idea what might be going on? I cant imagine this is right. At that rate ill be burning through my 20000mah 12S setup in no time.

I had the same results.
I had 130kv

Do it again without prop. Let us know.

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I am pulling between 80 and 95 amps at full power while riding. I have never checked the amps under a static load but imagine they will be much less once moving forward through the water.

Ah duh. Thats a good point. I bet you are right. I was worried that something would blow up if i was running 150-200 amps constantly, but once up to speed hopefully current draw would be a lot less.

that’s huge yes… i don’t think i went much above 100Amps… I reached 5kW max when pushing the speed as much as possible, but i foiled below 2kW most of the time… so you should be fine…