Cheap Board & 3D printed Foil - thoughts

Hey guys, just starting my build. and i’ve a few questions. Been following a lot over the past year but bear with me if I end up sound stupid.

So I’m 3D Printing the hydrofoil in PLA: [Kitesurf Hydrofoil Plans by berryd - Thingiverse]! - added a hole down the mast for cables

I’ve only one piece yet to print - using the heating method and sticking the parts together at the minute - Very Cheap Micromake C1 but I’ve it fine tuned now :wink:

Plan is to fibreglass the mast & fuselage together and then fibreglass the front and back wings separately so they can be swapped out for angle etc. I’ll post a picture once I’m home - currently in UK for work.

I’ve also found a Old Windsurfing board - 3.3m long, 11cm thick and 65cm wide - pic below

I weight 82-85kg depending on if I’ve had dinner or not that day!!! The foil (without the propulsion unit) is about 2kg. Now taking about 3kg for the propulsion and then the electronics and fibreglass I’d be estimating a total max weight of 95kg hopefully a bit less - I’d like 90-92kg if I could.

Could anyone tell me if this board is suitable for use and will it float with me and all the bits on it?

Could also do with a link to a diy vacuum boarding and a link ot ideal board shapes and sizes for the above weights as I’ll be cutting the board down to size - its so large I may even get two 1.65mm Length boards from it - would be nice for my eventual mistakes!

All help greatly appreciated

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I don’t know anything about the board or the methods but I can give you some information on how I 3d printed my foils. I would do some thinking about the connection of the mast to the board, I had some trouble with it and I ended up needing to weld the mast to a large plate.

I made my surfboard out of foamboard coated in fiberglass and I 3d printed my foil. The shape of the foil is something you want to get right in the CAD, though the profile is not super critical.

My first printed foil was too small and I couldn’t get enough lift. I coated this one in fiberglass and spray painted it.
The second foil I printed was almost twice as large and I was able to get up briefly before my motor controller burned.
I added a metal reinforcement to the inside of both of the foils.

Remember that the lift is proportional to a constant, times the area times the velocity squared. The constant has a maximum value based on your profile and angle of attack, and the velocity has a maximum based on your drag. You need to make the surface area large enough to lift your weight. My foil had a total SA of about 200 in^2. I weigh ~80kg.

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Nice info.

I googled a lot and found some eppler 817 profile that was working for some light builds (windfoil, kitefoil and some behind the boat mini catamaran i think) and drawed it in Fusion to see the area i would get. I kept profile scaled to it’s “%”. Somewhere on yt some dude was making it and complained that it was kinda limited top speed but huge lift, he sanded top off, rounded LE a bit more and got better top speed. Whats funny, he didnt notice any loss in the lift.
Where did u insert metal reinfircement? just where the screws go or like 2 metal bars crossed along the wing? I am very sceptic doing it only with glassfiber. I dont have any experience with it so dont actually know how much weigth and bend can it take.

The eppler 817 is actually the profile I used:

The blue bits in this picture are the metal reinforcement. I had holes in the 3d print that fit the metal bars. They don’t go all the way down, I just bought some cheap aluminum off amazon. Having the metal also makes the connection to the fuselage a lot nicer.

Glad to hear its working. I got a lot of metal bits laying around at my workplace, just have to redesign wing to have a bit more straight area for reinforcement, current is too curved.
I got glued eps block and still struggling should i go fiber mast and water cooling esc or get aluminum mast and somehow attach waterproof aliminum box on top of it for passive esc cooling (simmilar to fliteboard). I do like big metal sheet on the bottom of the board for good passive heat dissipation but i have no idea how smart or how heavy would it be to glue metal sheet to eps.
Is 20mm (tallest/fattest point of the profile) 3d printed profile enough for front wing? How thick is your backwing?

This is current profile size i drawed and i am not sure how fat should the profile be. Fusion says its around 560sq cm (86 sq inch) 1 half. I am around 70-75kg. I am still googling aspect ratios to get the logic.

If you’re interested, I can upload my CAD files for both wings.

The second front wing I printed was 25mm thick at its thickest point. The back wing is 10mm thick. Note that this one should have an upside down foil since it should make a downward force for stability.
I took the sketch from the airfoil website and drew over it in the CAD software such that the length was the size I wanted. I made mine 9.75" since that’s the maximum I could put in my printer.

I did a basic calculation again and each foil is ~96in^2 with a total of 192in^2 for lifting. This is probably slightly larger than I need.

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I read your comment and there is something very interessting. You say the back wing must have a down force for stability but I have bought a crazyfoil mast and wing. And when I check the configuration I see that both wings have a up force…no down force…What doyou thing about?

Thx for the offer, i will be interested when my wing turns out like crap which it probably will. I am experimenting with shape to acomplish kind of medium aspect ratio with a lot of area and preferably as thin as possible. Back wing will be made with no curvature so i can flip it for up/downlift. Adapter will be pretty easy to do. We plan to add a lot more fiber for later sanding and slight reshaping (thickness) to see the results, but 1st just need to learn how to fly. I am doing it with a buddy, he is 100kg so we aim wing somewhere in the middle, maybe slightly towards him. That goes for a bigger than needed board too. Will see what electronics say if esc cooperates. Still have to choose it O,O

Negative backwing lift oposes kite pull since kite pulls at an angle (anything between horizon and 12oclock), not strictly forward (depends on the position in the sky) and front wing gives positive lift to keep you out of the water. Idk the effect with efoil (pure forward), if backwing is mounted to give positive lift, we should have slightly more lift in total and center of the lift would be moved slightly to the back. What happens with negative backwing? We have to lean more forward because center of lift is then moved even further front? I am guessing this is not kitefoil, rather wakefoil?

Two lifting wings is a canard configuration. I’m not sure anyone on the forum has made an efoil with one. Though it’s more efficient, it’s less stable than having a back wing that has a downward force.
You can look up some reviews on canard hydrofoils from kite surfing, riding them is very different from riding a regular foil.

Hi @Filip, I liked the idea of using bars within the wing! I would put the carbon fiber ones (since it is lighter). So main wing has two printed parts? What about the rear wing? is it one part? Does it have a supporting bar as well?

Can you please post your design files?

I’m going to make a more detailed post sometime soon. In my opinion, if you’re going to spend money on carbon fiber rods to put in you might as well spend money on a real hydrofoil since it’ll perform better than one that you design yourself. I’m not sure the weight of the aluminum is a huge concern it’s pretty small compared to the weight of everything else.

The rear wing was also printed in two parts. I put a piece of sheet metal in it to reinforce it and mount it.

Hi Vincent,
up-force or down-force is just a matter of your angle of attack. So if the line between the trailing edge and the nose of your back wing is pointing downwards you have down-force. A few degree is enough:

I’m almost 100% sure that this is the case. If your elevator has up-force you get a resulting moment which tries to pull the nose of your board downwards and only the thrust of your propeller produces an opposing moment. You will have a hard time trimming the complete board by moving your body backwards to get a resulting moment equal zero. Furthermore, your board won’t be stable, since dc_m/d_alpha is no longer negative in the relevant range of pos. angle of attacks … almost impossible to fly. Just did a test calculation to show the effect of neg. and pos. angle of attack of the back wing.


Hi. Thank you your answer. I not an expert and not sur I understand everything…

I have found think instruction and mount possibilities . What do you think about?

Hard to answer without knowing the profile of the foils and the angle of attack they are mounted onto the fuselage. Considering you have a 2-4 kg battery in the front and a propeller, not a kite I would go for one of the standard configurations. Among those I would prefer the ones with a larger planform of the main hydrofoil.

But … the other configurations look very interesting :sunglasses:

Here is a link to how I built the foil

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I am John from karbon composites.
We know that your company deal with hydro foil business
we are carbon fiber hydro foil factory since 2016.Our factory is located in Dongguan city.
we only produce carbon fiber hydro foil.
we hope that we can offer OEM service to you.
Waiting for your response.
Thank you
John Mo