Simmons theory in action: dynamic lift generated by high and low pressure along the leading edge of the foiled rail, guided by two small directional stabilizers placed along the rail where pressure is highest. Trans span flow diagonally across the bottom of the board like an aquatic airplane wing. Board is 35 lbs and made of solid wood, yet it is on a rail and accelerating rapidly. Explain what is going on here and you will explain a lot about the foundation of modern performance surfboard design.