How do you ensure the resistance of bottom? To get a good tranference of stress between mast and board? i am not sure mine will work. I used plywood 10mm thickness with carbon and aramida. i dont see it solid. Any experience with plywood? thanks in advance
Hi.
It’s just foam.
The black part in that diagram is just the board foam, the blue part is the high density foam. You could use plywood instead of high density foam it will just be heavier. The high density foam where the mast attaches to the board only has to handle compression load. The hole as you see in my board where the wires go through, just like lift uses is very important for structural integrity. The carbon fiber in that hole joins the skin on the bottom of the board to the skin on the top, which is the bottom of the battery box. Because of this the mast mount is very strong and cannot delaminate. The bolts screw into nutserts that are epoxied into the foam and sandwiched between carbon fiber layers. The carbon fiber must be very thick where the mast mounts to the bottom of the board.
I hope this answers your question. Good luck with your build!
Thank you! That was clear.
Hey how are you water proofing the motor?
Hi.
Welcome to the forum.
Please do some reading and searching on this forum. You will find a lot of information on this subject, and information on more complex issues you will face while building your DIY board.
I hate to say it, but there is no way around the 5+ days of reading time needed to wrap your head around everything. You’ll see your read time under your stats. You’re currently at 27 minutes.
Please get some time in reading, and researching your build. Once you know what you want out of your board, we’ll be here to help!
Good luck, and happy building!
As FJ said, reading time is your best friend.
However, learning how to (ab)use the search function should be your primary skill, with keywords like 80100 or 63100 or 6384 which all are outrunner motors requiring modifications
Actually been here for 2 years but lost access to old email account. I see they are seals but I can’t figure out how to build with sss 56104 motor. I just recently got back into trying to build a foil again so figured I can try again but ask for help this time.!
Its alright i will just try the stuff I use for drone and esc, and remotes.
Before you judge someone by ranking maybe you should ask.
Hello guys, my name is Léo, I’m from France and I’m building an efoil also.
I will begin to build my board in the next weeks.
I have few questions for you @Flightjunkie . It could really help me 
First :
Secondly concerning the top of the box :
By the way congratulation for your work and your post on the forum. It helped a lot.
cheers from France!
I have a few clearwater foils. They work fine. Maybe we can get him to make a hollow mast!
We finished “building” the 2300 cm² universal wing with the hollow aluminium mast some time ago, and are looking forward of testing it this summer.
The plan is to be able to foil as slow as possible as the max speed here on my home lake is only 9km/h
Hi.
The foil attachment area core is high density foam. The strength comes from the carbon fiber. The area where the mast plate sits is layer much thicker for strength. The force is compression. So a wood core, or high density foam, or Carbon tubes, or something is needed internally to prevent the core from crushing.
The holes most obvious function is for the wires to pass through. But, the holes more important function is structurally connecting the bottom layer of Carbon fiber to the layer of carbon fiber on the top (bottom of the battery box). This prevents delamination. Nothing tricky. Just cut the hole and carbon fiber or fiberglass it.
The fasteners are flange nut type, sandwiched in the lamination process.
The battery compartment lid doesn’t need to be concaved. My buddy helped me build this board and he had a CNC, so it was easy to do that and it saved some weight.
Hope this made since. Still working on my coffee this morning… yawn 
Did you make any progress with your build? I didn’t mean to shut you down. I suggest using the 65161 motor and filling it with…yes, you guessed it! CorrosionX!
Unfortunately I don’t have friend with a CNC, so I will wire cut the board. Out of what material did you make the lid?
Also what hinges did you use?
Thanks!
High density foam for the lid. With carbon fiber lamination.
Latches are Gemlux
Hinges are Gemlux friction hinges:
Hi Flightjunkie, what a professional looking board!
What are the dimensions (L x W x H) of the hd foam for the foil mount. Did you use pour foam or glue a machined block? Is there any glass/ carbon between LD and HD foam? What is the thickness of the LD foam above HD foam, and why did you not have HD foam all the way to the bottom of the box? Many thanks!
Hi. Thanks!
The HD foam was just cut from a block. The HD foam is only needed where the mast bolts to the board. Otherwise the forces will compress the foam core. The HD foam replaced the other foam in this area and is sandwiched between the Carbon fiber on the bottom of the board and the carbon fiber on top (bottom of battery box).
The other dimensions you asked about aren’t important. Size it as needed for your board.
Hope this answers your question.
Thanks for the reply. So if I use the nut plate nuts with depth 10mm, I would add a HD foam section with 10mm thickness just bigger that the mast mount contact area? Would this have enough strength with 3 layers of 6oz/200gram 2x2 twill cf on each side? I am just trying to make sure my foil mount is strong enough.
Hi.
I would say the bottom of the battery box. Bottom of your board. Where the foil mounts. Sould be at least 1" thick HD foam core. Yes. 3 layers of 6OZ carbon on both sides should be plenty strong. Just make sure the hole is glassed. Because this structurally bonds the top and bottom laminate together. If you don’t glass the hole, the bottom layer will probably delaminate under the loads.
Do you think that regular EPS foam with a aluminum plate with CF over it would be okay?
kinda like what @wardy did
