Foil Drive Assist, DIY

OK, and no added capacitor pack? 32amp on 6S is pretty amazing! You are one of the few running a 2 blade prop i guess.

Without capacitor pack… I used short wires.
2 blade Prop have a better ETA, higher rpm and smaller current.

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Thanks Frank! I see the motor is 120kV in one of those shots… can you share where you got the motor from? And man those stats are impressive. That would be 800W foiling… Any chance you can elaborate on the prop you are using to get that efficiency (or is it a secret :slight_smile: ). Custom prop I assume.

Outrunner is from Ebay
High Aspekt wing
Caprinha Mast (15mm)
Light board
2x 6s Lipos 12Ah for good 35min ride time
17kg complete
And a small driver (65kg)

The Prop ist 190mm, and 7,5zoll Pitch, designed from enzymfax here in this forum.
Is not a secret :blush:

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Awesome. I’m a similar weight so a similar setup should work well.

Couldn’t find the prop guy on the forum ( any chance you can add a link?).

How many hours do you think you’ve done on the build so far and is there anything you’d do differently?

First water testing today for my DIY foil assist motor. It’s taken around two months of sourcing parts and building everything. A big help from a few forum folk. Hopefully this is robust enough, time will tell.

The motor has enough power to get me up onto foil on a sup in flat water.

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Well done. That looks super professional.
Now how can I get my hands on your build list :)…

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Yes please a parts list! Would really love to see that connection from the phase wires into the control box. That would really help clean up my builds.

I’ve used a rubber sheathed wire for the motor.
Aristoflex 0.6/1kV. 2C + Earth in 2.5mm2.
This cable used in commercial electrical submersible pumps

Used a nylon cable gland through the box into the ESC.

All up it’s cost $1400 AUD (excluding 3D parts) The box I went for is the explorer 1908. This seem the right size to fit a 6S4P battery, ESC and cable connection into with a bit of wiggle room.

Still in early water testing stage so need more confidence it works without breaking before listing a BOM.

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Quick update on the Water testing. DIY system Is working great so far. Plenty of power to get foiling downwind and amazing in waves. The PETG printed prop mount failed on the sixth session. I could see it was starting to stress crack. Version2 prop mount now ready to go. I will eventually send parts off to be SLS nylon printed I think. More mods to the motor plug to anchor the motor wires and give more torsional strength. Enjoying the constant design evolution and efoil revolution.



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Any idea which ESC FoilDrive is using? It`s passive cooling and looks like having no problem with 120A or more?

I weighed my motor and battery box kit.
Everything totals 4kg exactly, the box I have is about 700grams. I like the box, seems very robust and has a convenient carry handle. Available colours in orange, green and black.

My ESC is the Turnigy Marine ESC 150A.
Out of stock on HobbyKing global currently!

Here is a pic of my case with 24 18650 cells inside.

I have the same box!
but I went for 24 MolicelP42A since there’s enough room.

I am still finishing mine, but I noticed that the box is not really waterproof: at least in the one that i got, if you submerge it you’ll notice that water comes inside, so I’ll be replacing the gasket with a ticker one.

Looks awesome mate. Obviously it’s taken a heap of time and learning, but that’s part of the fun. At $2k (AUD) less than buying a Foildrive, would you do it all again?

I’ve been tossing up buying a Foildrive or DIY’ing, so I’m also looking forward to a parts list when you’re ready to share.

My box is holding up so far and staying dry (touch wood). I am putting tie-down straps over the top to fix it to the board. I think this adds a bit more compression onto the seals. Another downwinder today in light 15knots. So far so good. I’m starting to leave the motor on my mast more and more!

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Which folding prop design do you use? Do you know the pitch and the diameter?

then your seals are probably better than mine. In my box the lid is almost touching the box when it’s closed, so it’s not possible to compress it more.
btw, yesterday i changed the original seals with a window seal that is thicker and now water does not get inside. It’s a really nice box for the price

My advice to anyone is don’t demo a foil drive unless you are willing to part with $3.8k or build one yourself! If you are a SUP foiler or getting in to downwind paddling then they are a great tool to have. They should only ever be used well away from other surf water users. The last thing I want is a fleet of these at my local lineup! It opens up spots currently never surfed by any water craft in my local area.

Some Pros and Cons

FoilDrive (Official)

  • Works out of the box
  • Customer Support and spare parts
  • Aussie made
  • light weight, compact
  • maytech remote with a sticker on it
  • needs washing after every use

DIY

  • If it breaks, you can hopefully fix it yourself
  • endlessly searching websites for suitable parts
  • waiting for parts from China
  • getting a parcel every day for a month.
  • need a 3D printer
  • maytech remote without a sticker on it
  • still needs washing after use - aluminium, copper, saltwater and electricity are not a great mix.
  • building a suitable battery - spot welder required
  • guessing what will work - kV, prop diameter etc
  • satisfaction when it does work!

Foildrive have changed my view on efoils and hats off to them. With this kind of system you have the benefits of a little boost, but it still feels like traditional foiling. It is targeted towards real foilers and people who just want more stoke when on the water with limited time. I’d like to see a DIY targeted kit that could be self assembled. Maybe foildrive v2 will have more custom parts now that the initial uptake has been very positive.

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Do you know if Foildrive have bothered coating the magnets etc? Or have they just thrown the motors on and hoped for the best?

I wouldn’t hold my breath. There are certain elements that result in a healthy profit from a complete kit (batteries etc). You lose this if you just supply basic parts.
I’d be interested to know what the max speed for the foildrive is in the water (I should also google it as I’m sure its somewhere)…

So still going through the testing phase, but working great so far.

Happy with the electronics, I’ve shortened my cable length. Still have plenty coiled up in the box incase I want it longer for a different board.

New stronger 3D PETG prop hub seems to be holding up. Who else is doing a DIY build with any success?


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