Carl,

I remember not too long ago you were talking about once sailing a flat bottom planing catamaran and remember you said it appeared to be very unstable and difficult to steer (correct me if I mis-interpreted).

I remember a while back looking into designing a set of floats for an R/C airplane I once had. You will notice that most, if not all, airplane floats have that same type of 'turbulator' and if I remember correctly, my research at the time indicated that that step (similar to the step in the old 'step hydrofoil' racing powerboats) was important for steerage and stability of the hull at slower speeds. Perhaps this is the intention of this step. I've got to report to jury duty here shortly but perhaps someone will have some time to research this a bit.