I'm finding my 50cm board a bit too big much above 25kts, especially if it's choppy.

I had a go on the Thommen, and it's fine in the strong gusts but at about 50l horrible in the lulls!
I'm getting too old to wallow around up to my waist in water.

So I'm considering making a board with a stepped bottom, somewhere around 42/45 cm on the bottom and 50cm on top, the step about 20/25mm deep.

This will involve a bit more work than a conventional arrangement, so what happens if the board is fairly thick?
Say 130/150mm for 42/45 cm wide, does it make it unstable, increase wind resistance, or make it more likely to do that rail trip thing when the fin lets go?

Why is the Thommen and some other speed boards so thin?

Ian's asymmetric ideas have also got me thinking, but first I need to decide how to get a bit more volume.

Any ideas, thoughts, suggestions all welcome.