Funny. My dad and I just finished building a board (efoil) with Aramide (carbon/kevlar).
It’s the 1st and definitely the last time my dad will use Aramide as it’s a pain in the a$$ to work with.
The color we used on the board changes when you look at it in another angle
(color is mixed in the epoxy)
I found plain carbon a pain and that was just for a few repairs. He is a very clever man and looks like he has done a great job though. Strenght and less weight are the rewards.
Its a very different design from the boards we have here. If you going to keep developing shapes, you might find the site below helpful. The big advantage being you can tweak it a by a few mm and then have a surfboard firm with a 3d cutter to reproduce the shape in 15 minutes. You can also carefully “measure” a board you like and copy it.
The blank used is a CNC’d version (XPS), and the picture does look a little bit strange this way.
The board is upside-down, and taken from the front. (so you are seeing the bottom front side).
Problem with the aramide cloth is the sanding of it.
When sanding it, the carbon strings sands well, but the kevlar strings do not sand well at all.
It gets fuzzy. So to make things nice and smooth is really hard.
You can solve this by either adding more epoxy, or putting a layer of fiberglass over it.
Or… Leave it as a tennis ball look
We used more epoxy, and sanded it down again. Lot’s and lots of extra work.
My dad thinks that we could have made the board at least 2KG lighter if we only used carbon. (its now just over 6.5kg)
I have never sanded kevlar. With a foilboard, does having the bottom smooth increase paddling speed? In Australia we can buy “white Knight” brand clear acrylic spray cans. God knows whats in it, but it gives a surprisingly tough high gloss sealing finish. It will not fill dimples like resin though. Certainly OK on the deck I would think.
Vacuum bagging will make effective use of the resin and reduce weight/maintain strength. I have seen factories use it, but takes skill.
Shape wise, is it worth considering a long concave at the nose to compress air/froth to lift the nose in conjunction with the foil? I have only seen 2 broken foilboards here, but perhaps the strength is needed towards the rear? Would conventional round rails at the front (more comfortable for paddling) giving way to hip rails (top deck only) before the foil mount underneath give more rigidity for pumping?
Shape, rails and even a smooth bottom does not really matter here.
It’s an eFoil. As soon as I press the remotes throttle, the board will come out of the water and will only be using the foil. (theocratically most of the board is not needed anymore!)
We have an inflatable board here too. You should see the bottom and rails of it. They look horrible “flow” wise (a brick is more hydromantic)
And yes. Most strength is needed at the back of the board as this is where the foils mast is attached.
re: " tough high gloss sealing finish". We are using Double Coat DD varnish for this. Tough and glossy finish