Can somebody explain to me in simple terms the physics or hydrodynamics of pumping the sail and the board? I don't need to know how to do it, but WHY it creates acceleration of the board. Please note that I am not an engineer . I don't need complicated formulas,only the concept.

Another question I might ask is whether the floatation of the board (and the planing) is better in deeper water than in shallow water.
I sail in freshwater with a 180 lts board. Later the water level has come down to less than 2 ft near the launching site and I have been experiencing some difficulties in starting out.I have to walk the board for about 200 yds until I reach deeper water, which is quite annoying.

Thank you

Francone