I made my kiteboard out of some cheap 15/32 plywood scrap I had laying around the house. I felt that the plywood had too many voids and was too flimsy so I sandwiched on some 3 or 4 mm marine grade mahogany plywood scraps that I had left over from a kayak project I did. This of couse stiffened it up considerably as well as improving the appearance on the top surface. ( I did not put the 4 mm plywood on the top and bottom, just the top) On the downside it of course added weight.
I then used Z-Spar Captains Varnish, also left over from the kayak project, to seal the board.
I rode the board twice with no fins and then I put two fins right on the centerline of the board. I did not notice too much difference and therefore consider it unneccesary.
Understand I am a total beginner and the second time I rode the board I was staying upwind with no fins.
It is 122 cm long and 44 cm wide at the waist but flare out to 46.5 cm toward the tips (slight sidecut)
For such a short board it is a great light wind board but at 18mph and up it does not do too well as it planes out and won't hold an edge.
It weighs 10 lbs with bindings.
The bindings I first made myself with some mini closed cell foam lining some plastic straps that were meant for fencing material. I road it 4 times with pretty good results before one of the straps ripped out so I bought some very early wakeboard bindings at a boat shop where they didn't even know what they were or how much to charge for them so I said I'd give $10 for them.
Because I had some of this material just laying around the house from previous projects I only spent about $26 on this board.
Gorilla Glue $12
assorted hardware $4
glad that it works, but is there any reason that you didn't shape it like a kiteboard? surely the best way to design a plywood kiteboard is to look at well proven designs and take ideas?
bet its fun to make your own board and then ride it, also an absolute bargain
Check out fins4sale for cheap fins.
I've made several boards out of cheap 1/2" plywood. The ones that didn't use cloth and epoxy all broke. The boards that broke, usually broke in voids in the cheap plywood, during jumps. The boards that were sealed with cloth eventually warped.
I've switched to 1/2" birch plywood as it has no voids (5/8" would be thick enough).
I have no regrets trying different shapes and sizes out of cheap plywood. Once you find a shape that you like, invest in some better wood so the board will last longer.
I too like fins on the centerline of a board. With your sidecuts, the board is going to be loose when you are powered up. For a powered up board, you'd be better of with a rectangular board with 4 fins (1 on each corner). I like to round the corners so they are blunt.