When first I heard of this, I assumed that a smaller less lifty tail would allow the rider to stand over the foil, and not out forward where it would exert leverage on the foil and thus putting more weigh on it. But I’ve since heard/read references to bigger tails lowering stall speed. So what gives? How does it work?!
I think it’s all about surface area and foil section. Smaller tails will generally let you go faster so you can stay in the efficiency range of the foil. Bigger tails will give you more low end and grave digging potential.
So a different tail doesn’t allow a foil with a given rider to go slower, but rather to more effectively pump back up to speed? That makes sense. I’m totally retuning my setup since I changed boards from the fg. In order to keep from launching with the mast all the way back I had my smallest tail at the time(178) shimed -1°, and base shimed at the front to reduce aoa. I got used to small tails for winging too, so when I got an 1150/460 for dock starts I was startled by how aggressive that tail was. Now I’m going back to my larger chopped 220 tails at one or two bumps…
Most info I’ve seen has the main foil to stab angle of attack delta in the 2.5 to 4 degree range. Stall angle for even the most aggressive high aspect foil is going to be above 6 degrees, and 10 or more for anything considered user friendly. So, at stall angle of attack for the main foil, the stab is in the majority of cases generating lift, not pushing down, and more lifting surface means lower stall speed.
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Of course! I’m kicking myself but also satisfied to know that now.