Foxyirish Build - Ireland

Hey Guys, builder here from Ireland, I’ve been doing watersports from windsurfing , skiing, Wakeboarding, Surf & SUP to Kitesurfing, landsailing and diving and most variants in between for over 20 years so when I saw @pacificmeister on youtube I knew I had to get an efoil!. I’ve been surfing the forum for the past 2 years and gathering funds. I’ve been delayed a few times due to moves, getting married, buying a house to fix up and building a shed (I’ll post a vid of the shed for laughs!) so now I’m almost free to focus on this!

Just managed to get most of the pieces together - ended up pulling the trigger on most items over the past month - got sick of looking so rightly or wrongly my items so far are:

MP70131 120kV Motor = $200 delivered
Flipsky 60V 200A FSESC = $250.45 delivered
“Waterproof” Remote - Condom solution on this for now = $27.52 delivered + Conformal Coating = $25
14 no. Boston Swing Batteries - 58.8V 42Ah = $380 delivered ($145 was delivery!!!)
58.8V 10A Charger = $85.71 delivered
Board is an old Windsurfer cut up - needs a lot of work but have other spare old ones about if I mess up. Not cutting until I have all of the electronics up and running.
Mast Windknife FF13 - £50 del but I bought 2 so £100 ($129) - very suprised at the strength it has!
Fuselage - 20x20 Al Profile - Plan on Aluminium welding these together
Wings & Mast/Motor Clamps - 3D Printed Carbon & Fibreglass - this may not work out but its fun to try!
Pump for watercooling
Plus all the extra Bits like hatches, connectors etc. - never ending list!

My ultimate goal was cost up to now and I’m glad I procrastinated long enough for a direct drive solution to pop up rather than gearbox (could be eating my words yet). So that brings my total to roughly - $1100. So i’m probably looking at $1500-$1700 with the rest of the pieces and consumables all in at this stage assuming I don’t break anything - and of course we can not allow for hours spend reading and researching and labor once I start - its a hobby right :wink:

Next constraint I’ve put on myself is to be up and running by April 2021 so I get the full season out of it. I’ll probably not get to spend much more money on it until after the new year with holidays etc. coming up but I’ve filament and my 3D printer and fiberglass is handy enough to pick up from a guy down the road so the Foil will be my main focus for the next month while I wait on parts.

I’ve the Windknife Mast - going to attempt Aluminium Welding with these Rods - hoping to replicate the test video but I could be dreaming - worth a shot! If not then I’ll get box section, and use rivets or get it welded - may not work either and I’ll have to purchase then!

This is just the first post - I’ll add more along with pictures as items are coming in.

Have to get a thanks into all the forum members here that have helped me so far - too many to mention but a few below - @Jezza, @MaxMaker,, @VeFoil, @theone, @Toto44, @stijnhof, @jnobile - thanks a million

Any questions or queeries, please give me a shout! Happy Building!

Note 1: 3D printer cost not included as I had one anyway which I needed to upgrade - so I have the FL Sun I3 Plus configured for Single Extruder


Hi Foxyirish, thanks for the thanks. :smiley: Whenever you need help, just ask. Good luck and lots of fun building it. Where in Irland are you located?

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Hi, and glad I could be of help; sounds like you are on track for a successful build.
Regarding that remote:
I have been through a few of these (lots of salt water usage over the summer).
My recommendation is for a much more robust waterproofing. I would disassemble it and give the electronics 5 - 10 (additional) coats of conformal coating, the coating it comes with is not quite adequate and failed after not too many exposures to salt water:
Also, I put a drop of oil on the trigger spring, since the first one quickly corroded & failed (it is not stainless!).
Alternatively, you can pot the whole thing in epoxy, which also worked well, but you will need to carefully isolate the the trigger area and on/off switch so that they are not blocked from the required movement. I used 3D printed parts to accomplish this. (Spring still would need to be protected with oil or something.)
Both styles of protection have survived the season, although I have more hours on the the coated one.
I also designed and printed some parts that I glued to the charging base to positively locate the remote on the inductive charger, since it’s otherwise hard to tell if it is in the right place and slides around easily. If you are interested I can upload these parts to the thingiverse or somewhere (is that the best place?).

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Down in South Ireland - East Cork so plenty places for testing! Now just to build it!!!

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Thanks for the tips! Knew i had work to do on additional waterproofing!

I’ve bought the same stuff as your link just a different supplier as they wouldn’t ship to Ireland. Is yours the aersol version? Just spray, dry, spray dry it seems? Instructions are fairly straight forward from the data sheet. I’ll oil the trigger spring too and if it fails after all of that then I’ll go down the epoxy route!!

Thingiverse would be ideal if you wouldn’t mind?

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Yes, I used the aerosol version. Many light coats from every angle, partial drying in between (~10 mins depending on temp & humidity).
I’ll look into getting some of my more useful parts uploaded.


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Just need the remote now!

Windknife Mast

Aluminium 20x20 extrusion

Board - old windsurfer

How is this mast fixed?

Still have to work that out :wink: but im thinking along thr lines of a 3d printer version of A mast plate and rivit the mast to it 3 times on each side then fibreglass it to seal it.

Boston Swing 5300 Batteries have arrived! Very well packed

MP70131 Motor has arrived too! Also very well packed and doubled boxed but additional €51.40 for import tax :rage:!

Has 10 AWG wires on it. Cables look to be sealed but a bit pulled on the sealant from cables bending the way it was packed. Ill ask the supplier whats the story but it wont be going in water for a bit anyway so I’ve time to resolve. Looks to have threaded grub screws for mounting on the mast clamp which will be a plus…though they do look small!

@jnobile did your motor arrive with the same cable stretching the silicone sealant issue?

The first motor (100kV) I got straight from the manufacturer in China had a hard potting material in back, and the wire insulation was well attached to the potting material. There was one wire with crushed & torn insulation that was easily repaired with adhesive heat shrink. The shaft had broken through the box, but it was not damaged. This motor has been perfectly reliable for the whole season.
The second motor I recently received (150kV) from Alien had the elastomeric rear potting material, and the wires appeared to be well attached. This motor, unfortunately, suffered from an internal winding short (overheated or manufacturing defect) the very first time I used it. It was supposedly rated for 76 amps max, which it briefly touched for a couple of seconds in start-up, although the average current was 60 amps over it’s 2.5 minute life (it foiled on about 40 amps). If you are using the 150 kV motor, I would not use a prop above 5.5" diameter (the 5.8" prop I was using was not letting it get up the max output power rpm (3500) prior to foiling). A 5" diameter prop with 5 - 7" pitch would probably be good starting point for this motor, although I did not get the change to test that.


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Did you guys managed to get the max theoretical output power of this motor ? I dont mean to criticize but here is the deal :
70 mm and 130mm can does not allow you to push more than 7kw peak on it. This is proven with simulated electromagnetic field of the stator :sweat_smile::rofl:
Plus, this motor only comes with 10 awg wires :roll_eyes:

It works for @jnobile and was cheaper than the rest…said id give it a go. @jnobile did yours come with 10 awg wires?

So I got a chance to open up the battery packs and quickly assemble them just so I could see.

Briefly plugged in the charger too and attached it just to see and besides the tiny wire I used (all I had for tonight) smoking…def not built to take 10A :sweat_smile:, it was all good.

Probably gonna assemble in 2 stacked rather than 3 and make it longer but i’ll have a think.

Hoping ESC is due tomorrow and remote next week.

Very Happy…course cant check Ah of the batterys yet so :crossed_fingers:

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The 100kV motor came with larger wires than the 150kV version, which makes sense, although I don’t recall what size either of them they are.

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My system needs ~3kW to get up on the foil and ~1.8kW to remain foiling, so I am getting what I need (from the 100kV motor) for the top half of the battery (50-45V). Below 45V is hard to get started, especially in fresh water.

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