foil board bottom - flat vs concave?

[JEG]

besides the bottom shape, sharp, round and rectangular I notice most prone foil board have double concave bottom and most sup foils board are flat and also some have slight single concave. What's the advantage and disadvantage or is just a minuscule design advancement or artistic design?

[Califoilia]

Here's my current SUP foil ride bottom....

...6'0"x29"4.75" 115 liters

My first design was flat-bottomed (like all the others I'd seen at the time), and I initially had the concaves put in on my second board (Nov of last year) with the thought of getting air under the board quicker in order to break the surface tension of the water along what was the flat bottom before, to get the board to lift sooner, and fly quicker.

What I inadvertently found also, was that once in the air, the air seemed to have better flow and was more organized (if that makes any sense), and thus made it much more stable and predicable to fly, and set in and out of the turns.

Hope that helps.

[red_tx]

Here's my current SUP foil ride bottom....

...6'0"x29"4.75" 115 liters

My first design was flat-bottomed (like all the others I'd seen at the time), and I initially had the concaves put in on my second board (Nov of last year) with the thought of getting air under the board quicker in order to break the surface tension of the water along what was the flat bottom before, to get the board to lift sooner, and fly quicker.

What I inadvertently found also, was that once in the air, the air seemed to have better flow and was more organized (if that makes any sense), and thus made it much more stable and predicable to fly, and set in and out of the turns.

Hope that helps.

Sano, will you make me one please?
-red

[frenchfoiler]

I used to have flat bottom on my sup foil and now I added a deep double concave (front half), I think it gives more stability, more tracking and helps lifting. Also it helps during touch down, more forgiving, the board doesn't stick and fly out quickly, super responsive.

I haven't tried on my surfoil yet but I definetly will ! I guess you don't need as much as on a sup as you don't need more stability, tacking and lift but for touch down it might be really good. Also it seems from the reports that it also gives more control when you hit the white water during a reentry for exemple which is always super tricky to land !

[JEG]

Nice bottom board design SanoSlatchSup. I wish I could make my own foil board but I need time and space to explore.