project_BeerWolf build

Hey all,
I’ve added the drawings for my build here in case anyone is interested.

I’ll try to add some pictures to the readme but you can see some at the end of the video linked in the description. I’ve spotted a few little mistakes in the drawings that I’ll fix but you could probably take these to a machine shop and have them fabricated. Disclaimer: I’ve barely done any testing! Don’t take the drawings to be fabbed just yet. There is a 3D printed nose-cone and propeller in there. I’m using half a shaft coupler to mate to my propeller, that is a little funny at the moment and could be improved.

Assembly Drawing



Awsome piece of work Robbie !
You’re my reference candidate to test the “Mast no drill option” :wink:
Builders: how not to drill your alu or carbon mast!

I have 2 questions: a Dwarfcraft is a no volume no balance board.
1- Aren’t you afraid not using a duct with you family jewels not so far from the the prop during takeof ?
2- Your tests on the water: have you thought about using a leash in which you could hold during your learning curve ?


I’m not too scared of it, the prop is pretty far away at the bottom of the mast while I’m lying on the board. I might hit it while swimming near the board, but I’ve been taking care to make sure the prop isn’t spinning.

If this was a aluminum prop, it would be a different story. The 3D printed prop would probably ruin someone’s day, but not kill them. A plastic printed prop is not a big threat when your balls are made of steel.

  1. I don’t think its so much of a question of learning. I can ride the foil on my kite and behind a boat no problem. I think that thruster is upsetting a force balance. I’m going to try taking the straps off so I can move up to the front of the board. I also might adjust my tail angle or thrust angle to compensate.
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Waterfox, have you tried moving your foot straps forward a little? Looks like you have plenty of power but the board is climbing too fast and throwing you off. Maybe just use one strap so you can move the other foot to adjust your CG. I have also found that once the board is out of the water I can back off of the throttle and the wing will level out.

Spring is almost here in Canada and it is time to start building a new board with more flotation and space for the batteries and controller.


The electrics and motor are working nicely. I designed for 14 knots and measured 13.6. I’m still having trouble getting it to foil. Taking the straps off helped a lot. It looks like you need to kick it up but quickly shifting your weight back and then moving it forward again. It seems like one side of the wing is stalling and throwing me off the side. I’ll probably try a faster propeller next time.

Tons of fun to ride around on. Time to start working on the waterproof remote control.


Couldn’t the thing that trow you off be the wires running more on one side of the mast that the other.
On my first try i had the running like yours and it wasn’t very stable, for my second try, the wires were running entirely in printed part like the one in the picture below.
the outside shape is based on the mast shape.
It helped a lot to get less erratic reactions when trying to fly :slight_smile:


Wow, I didn’t consider that. But that could totally be the reason it is so erratic. Time to start printing or drilling holes in my mast. Thanks Mat!

It worked quite well in my case, but going through the mast is still a better option …
now that i know my system is powerful enough (and that i have a new mast for kitefoiling), next step is mast drilling and building a dedicated board (my case almost fell off during last test :slight_smile: )

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What are your plans for building a dedicated board? That is next on my list too. Everyone seems to be chopping up old wind surfers.

i’ll make it from scratch.
for now i have a rough 3d design:
6 feet long, 27 inch wide, 4.7 thick.
main design parameter is the volume, i’m aiming at 100+ liter (i’m70kg)
i want it floating while standing on it.
Right now it’s exactly 114 liter, so i might make it shorter.
Very simple shape, flat bottom on the back 2/3. flat top, very round rails.
Some nose rocker , but not very pronounced.

Mast will be almost completely at the back (attached most likely with threads, not tracks.)
Detachable mast for sure, with 4 bolts plate (liquid force spacing).
Battery and electronic bays isolated from each other.
extra space in both for autonomy expansion and electronics improvement.

Hand shaped out of polystyrene block.
Most likely a balsa wood layer on top and bottom between polystyrene and glass.
2 stringers (wood or carbon) bringing the load from the mast all along the board. stringers will act as the sides of the battery and electronic bay.

the hesitations are on:

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I would recommend using a lot of round hatches and making the board completely hollow.

Hollow would give a lot of space… but how would you manufacture it?
and you’d also loose the “I-beam” effect of the foam that let you use thin fiberglass skins on top and bottom…

Three options I have been thinking about:

  1. Stitch and Glue method. Google it if you don´t know it. This can be done without a CNC. Everything would get covered with carbon fibre. And then two halves joined together. Very labour and CAD intensive to make all the wood parts and internal structure.

  2. Hand laminating or vacuum infusing 2 moulds. Making the mould is also very labour intensive. I could cut it on my CNC out of wood and then seal the fibres with gelcoat. 3 layers of carbon, then honycombe or similar and then 3 more layers of carbon.

You would make the hull and the deck separately, the deck overlaps onto the hull. To join them you insert the hull into the deck and the joint is filled with thickened epoxy as a filler. This would probably require a good amount of hand sanding the joint. Probably the lightest method.

  1. Use a foam core and then remove it afterwards manually or with acetone. Messy and you cannot make it as a sandwhich construction.

Hey Mat,

Thanks for the details. I was also thinking of hand shaping out of a foam core. Possibly with a wood or a core-cell deck to stand on.

I haven’t thought too much about how to do the waterproof enclosures, but that part seems like it will be difficult. I might just end up with 2 pelican cases embedded in the deck. Maybe there is some OTS boat hatch product we can glue in.

I have 2 Chogori Large Series IP67 connectors I may use to make the mast detachable.

I disagree with trying to make a hollow board. I have never seen a hollow surfboard. Huge structural and manufacturing cost to not having a core.

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Rated current, 20A…

I’d use 2 or 3 of those connectors. I don’t recall if that rating is per pin, I think it is.
They have different ratings 20A and 50A per contact.
I use a similar one rated for 35A per 4mm contact, tested myself with 80A permanent D-current.
Mine is suitable for 15 mm cable diameter, leads are 6mm^2 which corresponds to AWG10 in effect.
Cable and plug need some cooling by air at 80A, i use to wet them from time to time, if they get warm at all.
Also a 20A type with smaller contact diameter used to work without problems.

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Next time I’ll follow this suggestion. 12 bolts to hold phenolic hatch are annoying!
I had to build a mold of the size of my battery housing and do the box, glue the box in, brass inserts for the screws etc.
I could have molded the box and attached it on a flat plane (carbon or whatever), drill the round hathc hole and glue into the foam blank prepared. Then you just laminate, that ain’t a hollow surf, it’s just a box. (Aviso made a line of hollow carbon surfboard 10 or more years ago… cool idea, expensives, no luck!)
And I will make a single box with sections, mast plug and that’s it

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The beerWolf EFoil is now working and foiling reliably!

I bought a new 30inch mast and ran the wires and water cooling cable through it. @Mat you were right, the external wires were making too much drag. It is surprisingly easy to ride now that those are tucked away.

I am so happy that this is finally working. Now time to improve it! Waterproof remote, maybe a new board…