Modular eboard in Michigan

EFOIL.builders Builds
1

Hello!

I read this forum since few month, it’s a incredible source to build a foil board! I’m french (coucou aux francais!) but I live in Detroit in Michigan.

So as you expect, I’m here because I would like to build an E-foil board.

E-surfboard, but to do what? I like speed, sport, jump… cruising at 15 mph is not really my idea of my board.
E-foil are nice for riding, flying sensation… but maybe not for freestyle and jump? (it’s possible in kite and wake, I never see an E-foil doing jump)…
E-board are good for that and they are not really different in technology.

So i would like to study the possibility to create a board with 2 position for the motor, one in the foil, one attach to the board… both with propeller.

The motor, ESC, propeller and battery type need to be the same.

Probably in no foil, have a higher voltage/Amp battery pack, to have more power could be nice.

I will probably go for a 10kw motor direct drive, to have around 6Kw in foil, and full power in board.

Battery pack of 6S 12C 20 AH, 2 in foil (44V), 3 in a board (66V), maybe need 4 to have 88V?

Everything it’s quit clear for my board except… The propeller of course!
Small propeller with high RPM (15000/20000) or a bigger one with low RPM (5-6000)…?

A smaller one will be more easy to integrate under the board when I don’t use the foil. But I would like to have nice torque and a good speed cruising. (around 30mph)

Thank you very much for this forum!

2

There is a guy in my local hackerspace that is building a hybrid that can be an efoil or jet surfboard. Really seems like two different categories of RPM levels, but we’ll see what the final result shows!

4

Yes the power for both configuration are different, but it’s easy to manage with the number of battery to change the voltage.

The propeller is the pain point ( like always in general in this kind of project). I have access to a 3D printer to make some custom propeller. And one of my friend can cast it in more or less every metal. So yes if you can help me to define it could be really helpfull.

I also use the Vicprop calculator to define the general capacities of the propeller. With a 10 000rpm 10hp motor in direct drive, it give me a tehorical speed capacity of 75km/h with a 4 inch propeller with 6.2 pich, 3 blades.
Of course it’s the thoerie, so in real life I can expect a speed around 50/60 km/h.

I also need to work a lot on the foil shape to reduce drag…
One other pain point in foil is the turn capacities, I never seen a foil make short curve, if I understand correctly the wing loose the lift when people try to make a short curve turn… With the current wing shape it.s nearly impossible to take to much angle during the turn without loosing the lift.

Anyway, I will develop the prop system with the rocket directly attach to the board, it’s the configuration who ask the most power.
If I can have enough for the board It will be more than enough for the foil.

6

For the propeller I think in the begining I will try different version of some we can find in the shop, some of them are really cheap and it could give me an idea of which kind of propeller work better.
I can also reduce the diameter if needed, to find the right balance and cruising RPM/propeller.

Also, some shop propose to try different propeller for free.

I start to define the shape/design of my board, it will be the starting point of the project. So first I will make the no foil version:

plan
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Traditional construction, Foam/ carbon fiber, with some wood insert (probably fake for weight).
The board will be quit big, to have a low planning speed, and I would keep the board floating when I’m stop.

The motor will be direct cooling, I’ll using it in lake so it’s not to hard for the motor compare to salt water.
The ESC will be in the rocket, to keep a natural flow cooling and don’t have additional pump for this.

-first I will probably go for 3 pack of 20000mAh 6S 12C battery, to have 66V to the motor, I can adjust the power if needed.
-For the motor I think the APS 100100 INRUNNER BRUSHLESS MOTOR 100KV 10000W from Alien Power could be a nice option.

7

i post this link one more time because i just love watching it :

quelques idées ici:

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Merci for the link! :smile:

Really interesting, but in the video, lot of part are accelerate, so it’s hard to see the real speed.
I think the it’s quit slow, the propeller is really small with low pitch, no miracle the pitch is the key to have speed… The trouble it’s to find the right balance acceleration/speed.

The torpedo is not really different from the board to foil, I just need to have longer cable for the foil, maybe directly integrate in the foil, or store in the board when I don’t need the full length…

For the foil wing I will probably go for the composite crasyfoil, in custom mast and fuselage. Same they are cheap, simple, so nice for reference.

9

dia110mm pitch 143mm 6800rpm using a 56104 geared to almost full power (10kw and probably 15NM) , believe me it is fast, really fast, on a foil 35-40km/h you can “manage” but on a board with waves: all other story

10

I trust you, it’s just hard to see in a video.

I will use it in lake, it’s flat, but I see what you mean, maybe you right and the board will be too fast…

But I would like to keep a marge of evolution, at the beginning 44V (4400Rpm) will be probably enough, but when I will be more confortable with it I would like to keep the possibility to go faster if I want… Or not.

I use this website to “define” more or less witch kind of propeller will work bette in different setup:

Max speed defined: 30Knot (55Km/H)

For a 10 000Rpm motor with 10HP (9.5 at the propeller): 3 blades 4X6.5 inch (100X165mm)
For a 20 000Rpm, same 10Hp: 3 blades 2.6X3.2 (66X81mm)
So for My motor, 6 600rpm @ 66V: 5.1X9.9 (129X 251mm)

For all of this setup it give me a speed of 43.6 Knot.

For the video 13hp and 6900RPm , the best propeller in this website will be a 5.2X10.7 (132X271mm) for maximum speed of 49 Knot. (90Km/H)… it’ could be a race board! :joy:

So I’ll probably go first with a cheap 9X10 propeller and reduce the diameter to 6, it will give me reference, after I will reduce the diameter until the motor is in the good range.

50$ it’s not a huge investment.

11

i don’t think the 100100 has enough torque (8-10NM i think) to turn this kind of propeller, it is pretty heavy also, most propeller have variable pitch, if you cut it below 85% you will loose pitch

the alien 100 inrunner: tppower tp100 is close to it: for 10kw you will get at 66v around 6NM of torque for ±150A (my guess i could be wrong…)
on the video the 56104 geared is pulling about 13NM…with a “small propeller”

12

The website is theory, so yeah, maybe it will not working, but the idea it’s just to have a reference, and this calculator is a good starting point.

I enter on the calculator 10Hp gas engine, so 7 KW… and in general for torque electric is better than petrol engine, but maybe I’m wrong for this kind of small engine.

Gearbox will give me more torque for sure… I’m still struggling between direct drive or geared.
It’s the reason why I will start with the board, to let me the time to define my power unit.

13

Bonjour Erwan, je suis français mais je vie en France. Je suis super content de trouver un français sur le site et qui est dans le pays où il y a plein d’amateur de diy de efoil. Cela fait un moment que je veux aussi faire un efoil. J’ai beaucoup lu ce furom mais tout en traduisant. Je suis persévérant, et bon bricoleur avec des connaissance en electricité. Je compte réussir car je n’ai pas les 6600 euros pour m’offrir un efoil.

J’ai des petites questions si tu veux bien m’aider s’il te plaît :

Que veut dire Alexandre quand il te répond « dia110mm pitch 143mm 6800rpm » avec le moteur 56104 ? est-ce un réducteur pour mettre sur l’arbre du moteur et pour adapter l’hélice ?

Où en es-tu dans ton projet ?

Pour les batteries, je prendrai les mêmes que toi mais seulement 2 pack (44V). Mais en ce qui concerne le ESC, la sécurité et la télécommande tu as pris quoi ? peux-tu me faire un petit schéma avec la liste de ton matos genre comme celui la mais qui date de 2017.

Je voudrai un entrainement direct de l’hélice sans passer par un réducteur. Cela fera de pièces en moins, as-tu déjà mis le système de refroidissement ? et qu’a tu mis comme foil sous la board ?

Le petit frenchy te remercie d’avance et attend beaucoup de ton aide surtout pour la langue car ici en France ils sont très rares les Diy de efoil et très en retard par rapport à vous, sauf les professionnels qui gardent leur secret comme à côté de chez moi à Annecy et PWRfoil à Perpignan. Moi j’habite Domancy près de Chamonix et oui loin de la mer… merci encore.

14

Hello!

Sooo it’s been a long time since I’ve posted here, lot of things change since last time.

I put the board in pause because… I’ve bought a boat, it’s a '78 Mastercraft, skiboat but enough to have fun in wakeboarding. I did a small restoration on it so it take lot of my time. But it’s a fantastic toy!

First: vaiment desole rider, je n’avais pas vus ton message, je n’ai d’ailleur pas eu de notification… il y a un truc a activer? J’espere que ton foil avance (il est peut etre fini depuis… :sweat_smile:)
Perso le mien… rien foutu du coup. J’ai commencer a coller mes premier pain de mousse aujourd’hui, ca va donc pas etre pour tout de suite.

SOOOOO, I just restart the project, but it’s not bad because lot of new product sine 2019, I change a bit my project, it will not be modular anymore.
I think I will start to make an E-foil and if it’s good I will make a separate surfboard.
Why? because i want an E-foil with a propeller and the surfboard with a jet.

I just restart the project, here is my new plan:

new plan small
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SO I go for a 60V 30AH battery in the board, flipsky motor and ESC in the mast, better for cooling and wieght on the board.

I just packed the foam I will start to shape it tomorrow!

15

Start to shape the board, the goal is to finish the shape and resin work before it’s getting too cold here.
So I can spend the winter on the electronic to be ready for next summer.

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Few question before carbon fiber, I need to know few think for the insert.

My goal is to have a dynamic use of it, not just cruising, no jump but I really want to do carving.
I hesitate to put foot strap on the board, anyone using them? Did it give any gain in control?

If yes what is the best position refer to the foil? Can I take the Wing foil as reference for exemple or it’s different?

Wich is the best position for the foil mast mount? Rearward as possible? Or just enough forward to have the rearwing at the back edge of the board?

Question for balance, I would like to put the battery pack just over the front wing, good idea or it’s better for balance to have it between the 2 wings?

Thank you very much! Sorry for all my questions but I really want to try to make it correct.

16

Hello there! continuing the shape of the board, nothing crasy there but I think I’m pretty close to what I want, shape is done at 95%.

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Start the refinement and correction of imperfection, it will take a bit of time but it’s necessary to have a great finish.

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for people like me shaping the board by hands from scrap, who don’t have access to a miling machine but want a nice finish.
I find this product to correct imperfection without adding weight:

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This product is crazy light, the first time I bought a box I think it was empty, in fact it really easy to apply in to surface, cheap and easy to sand down.

Of course it’s not waterproof so it need to be used before fiberglass.

1 Like
17

Hi Erwan, I thought about strap too and decided to stay strapless. Something to keep in mind is you will have best case scenario a 25kg board under your feet… It is a lot of load on your ankles when you crash even at moderate speed. The position would also be really hard to figure out prior taking the board out a first time as it depend on many factors: your foil, your weight, position of the battery and even the length and position of your motor on the mast. Then lets say you change your rear wing aoa or use different wings, shorter fuselage ect, it will change again.
For the mast position it is also going to depend of the foil you are going to use. With any front wing above 1200cm2 you will most likely have lot of front foot so a mast position all the way back would be fine. But once you progress and use smaller front wing and rear wing like a 900cm2 or even a 800cm2 with a tiny stab the front foot pressure will decrease. On my current setup with a 950cm2 front wing and 210cm2 rear wing my rear foot is on the rear edge of the mast baseplate.I would allow just enough room on the deck to place your rear foot just behind the mast if you later use small wings

2 Likes
18

Thank you very much for your answer.

For the strap, a windsurf setup is pretty heavy too and when you fall with the sail going in to water it’s a pretty rough stop, i never get stuck on windsurf strap, but I never try windsurf foil.
I think I will put different position insert for strap possibility and see if I need them or not. At the beginning I think it’s useless but when you increase level and start to carve more it could be a bonus for control.
The weight of them are not critical compare to the global, and if I decide one day to go with strap it give me the option.

Totally agree for the evolution of the foil, so for the mast base I think I would like to put an adjustable one like this:

Of course it need to make enough space in the middle to allow the cable to slide with is.

19

The board is quit done in shape, I wait now for the insert and the access door to run with the resin.

I take this one:

https://www.ebay.com/itm/172257862848?hash=item281b5e64c0:g:nsYAAOSwEjFXdABL

For the battery, any recommendation? I would like to run 72V 25-30Ah if possible, I see this one:

https://www.aliexpress.com/item/1005002816051137.html?spm=a2g0o.search0302.0.0.60e91294sjb2P9&algo_pvid=1650766a-48de-4737-8f77-81ce13b7a383&algo_exp_id=1650766a-48de-4737-8f77-81ce13b7a383-8

This pack give me 7.2KW peak and 3.6KW running power, should be enough with the Flipsky 6KW motor.

I would like to have 2 maybe 3 battery pack (depend on budget) so I can switch when one is empty.