The Student Build - Beginner/Small Budget - Inputs Encouraged


#1

Hello everyone,

This is my first official post on this forum and I have to say that this community is great. I am really excited to be working on my first efoil project. After hesitating quite a bit due to budget restrictions, I ended saying what the hell and going for it.

To give you a little bit of background about me, I am 21 years old currently studying at Florida International University (why the budget concerns) and I am also a sprint kayak athlete. I’m originally from Quebec, Canada so I speak French as well and I had no prior knowledge or experience with building RC stuff etc. So, this is all somewhat new to me and I will need some input from the community.

Now let’s dig into what I have in mind for this build. So, I bought a brand new Cabrinha VMG carbon race board from a local seller on Ebay. It came with straps, and fins and everything was brand new. I paid 220$ for it which I thought was an awesome deal considering that I’m currently trying to sell the straps and fins and hope to get somewhere around 100$ back from that. I also bought a demo liquid force rocket foil from kite paddle surf which is in great condition for 320$ with shipping. Pro tip: If you are on a budget, I recommend to do extensive online research. There are a lot of great opportunities out there. Furthermore, you should contact big online sellers by email and ask them about their used inventory. Sites like ikitesurf.com , kitepaddlesurf.com, realwatersports.com, mackiteboarding.com and forcekiteandwake.com are all good shopping sources.

Now onto more specific efoil components, I almost got carried away there. So, I’m planning on doing a direct drive direct cooling set up. The 80100 APS 80kv and 130kv are both in my cart, but I can’t decide which one (Help me out if you can). I will waterproof the motor using mat’s technique outlined in this google doc I made from his instructions. The mast clamp files were also provided by Mat as he designed it for his build. I will be printing it in ASA on a MakerBot replicator 2x. The ESC will have a high amp capacity (300a-400a) since I do not plan on water-cooling it. If you have a spare ESC or a slightly used one you don’t use and that has between 300a and 400a capacity, let me know as I might be interested in buying it from you.

As for the battery pack, I figured I would keep it simple and buy lipo batteries. I am currently looking at either 2x6s 22ah lipo batteries in series or 4x6s 16ah lipo batteries (2 in series and 2 in parallel). However, I am also interested in building my own 18650 battery pack. I do not have any prior experience spot welding and building battery pack so I am a little bit hesitant about going through with it. Let me know if you have a simple way of building a battery pack.

I will mount the foil on a high density track box that will be layered in my board. If you guys know a cheaper and more reliable way of installing a foil mount underneath a race board please let me know. I’m also planning on making a custom waterproof compartment into my board that will hold the batteries, the esc etc. As per the remote, I was planning on waterproofing the electronics inside using clear nail polish and CorrosionX.

The only thing I bought so far is the board and the foil, therefore I am encouraging you to leave your ideas in the comment as I am looking to get more inputs on my build. If you have any questions, do not hesitate to comment and I will get back to you.


#2

Reserved for update 1


#3

Reserved for update 2


#4

Looking good! The board looks really nice.


#5

There is another one for sale here : https://www.ebay.co.uk/itm/New-Cabrinha-VMG-Race-Carbon-Kiteboard-Kitesurf-Maimi-Pick-up-only-/192026831240?hash=item2cb5b0e988%3Ag%3ApuIAAOSwB09YKSZW&nma=true&si=WhQlx7NQANwYLLcIpOULClS7oOQ%3D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

Very low volume though (82l)


#6

This is the one I bought actually haha! It was a Miami pick up only which worked out great for me!!


#7

Thanks!! Hopefully it can fly haha


#8

How much do you weigh ?


#9

Im at 170lbs! It doesnt float enough to be a sup by itself… I tried it :joy: with some speed though, it will be fine! This board has a bit more volume than the one pacficmeister used!


#11

Hello efoil builders, I figured now would be a good time to give an update on my build since I received most of the parts and since I started working in the board.

So most of my original ideas stuck around. However, as you can see from the pictures, I decided to build my own 18650 battery pack from 200 Sony VTC6 cells (3000mah). I also bought a smart BMS with a screen to monitor them. I ended up going with the APS 80100 80kv motor since I will run on 14s (14s14p battery pack). I also bought a 7.5in propeller with 8in pitch (hope it won’t be too much). As for the board, I already cut the holes for the foil box and the battery/electronics compartment. I am planning on fiberglassing those holes however I was wondering how I could push the fiberglass against all corners while curing. Could I fill up a big Ziploc bag with water and put it on the fiberglass? Will the Ziploc stick to the resin (resin research epoxy)? Lastly, my remote is still in the mail, I ordered the new waterproof model (posted on a post I made). If you have any questions or suggestions, please comment down below as I always appreciate some feedback!!


#12

I think the 80KV is the right choice especially with a 14S set up. I was going to ask how are you are going to mount the spline type prop on that shaft. But since your going with Matts build you will probably bolt the prop directly to the aft end of the motor. I am looking at 18650 batteries now. I also want to do a 14S x 14P set up. What Batteries did you get? Where did you get them?


#13

I now see your using 200 Sony VTC6 cells (3000mah). Those are nice. I have been looking at those, also the Samsung 30Q 3000mah, and the LG HG2 3000mah. They are less than $590 for 200 on E-bay. I am scared that they might be fake,


#14

I would not buy Li-Ion cells on eBay unless you like house fires.


#15

I tried HG2 samples from 4 different ebay us sellers all were fake!!


#16

I support that! Do not buy on ebay!! If they are dirt cheap they are fake!! I bought mine from jehugroupbuy.com for 700$ which was a steal imo! However, they are out of stock now and the guy had problems shipping them out so I wouldn’t recommend. I also had to wrap them myself since they were an overstock from a bankrupt EV company. If I were you I would Pick any of the 3 you mentioned; whichever is the cheapest!


#17

You can try the ziploc bag on a small sample, i would guess it won’t stick, but i had surprises with some plastic films sticking… you can always wax it to be sure.

But to reach your corners, i’m not sure water in a bag will do it… i really see 2 solutions: Vacuum ( not necessarily expensive if you build it on a salvaged fridge compressor) or you can make a negative shape out of foam, wrap it in a plastic bag and press on the fiberglass.
For the foil attachment, you already have the negative shape anyways :slight_smile:


#18

I agree with Mat on the vacuum solution - I was going to write you a novel about it but I got distracted.

The first thing I would do is put some spray foam in all inside corners, then sand until you have a nice smooth chamfer/curve. That way the fiberglass doesn’t have to make as sharp turns. If possible chamfer the corners on the outside/top as well.

I am looking at the same issue when I start cutting up my board. My plan was to put that gummy tape stuff right on the board and a large amount of plastic wrap and then vacuum it down. I’ll document my process and whether it worked or not, but it’s at least a month before I get to that.


#19

@dougm … you’re exactly right about rounding the corners. An easy way to do that is to apply thicken epoxy with a “ice cream stick” … keep it perpendicular to the surfaces and you’ll get a perfectly round corners without sanding needed :slight_smile:

one word of caution for the vacuum: you need a loooot of spare plastic to make sure it can “extend” inside the corners… i used a strechlon film with what i though was sufficient spare length, but it overstretched, breached and made a huge mess… that’s why it’s not visible in my video :slight_smile:


#20

Thanks for the suggestions!! I will probably round up the edge and use a negative to make sure the fiberglass takes the form. I’m trying to stay away from vaccuming as this will only add more steps to my build and I haven’t yet tackled the big project which is the battery pack. I read online that Ziploc would stick so I will go with that!!


#21

I’ll definitely round up the edge a little bit to ease the process! Thanks for your input! I’m planning on inserting a wooden frame into the side of the top compartment with threaded inserts. I would then glue a rubber lining all around and screw a plexiglass panel in these threads. Do you have any other solutions/ideas on how I could make this compartment water tight?