From Marc Andreini
"...what exactly makes hulls worth riding?
What differentiates them from McThruster?
"The simplest analogy to draw is: There's a hull and there's a hydroplane, the two basic hydrodynamic designs", he told me in April while we sat in his blue Chevy Suburban parked on the ocean side of Highway 101 at La Conchita. "A hull you would liken to a sailboat, which has a deep, rounded curved surface that extends down into the water. The pressure that the vessel has pressing against the water displaces water from the heavy rounded surface of the boat's hull as it passes through the water. It creates forward propulsion.
"Hydroplane, he continued, is a flat or concave surface which creates lift and brings the board immediately to the surface and planes on top of the water. The obvious differences are that one board quickly gets up to speed as it comes up on top of the water, but also quickly tops out, where you lose control once you get going too fast, so you have to put all kinds of fins on them to keep them in the water. Whereas a displacement hull reaches a terminal speed after a series of driving turns, and you build speed from one turn to the next.
"Another analogy is driving a stick shirt sports car, when you accelerate and power shift through the gears to gain speed. On a hull you're driving from one turn to the next, and the object is to connect yourself down across the wave into the pocket and bank off that angle and create additional speed. Unlike a hydroplane, you never reach a point where the board loses control. It's always attached to the water, and you maintain control at any speed. It's a more fluid, natural design that goes through the water more so in the way that a fish or a dolphin or a tuna would, as opposed to taking a flat stone and skipping it across the water, where its detached from the surface."
This Vid is a bit... ... ... ... ... But it does clearly show how the water differently disperses off the rail...
I think this might need to be my next learning curve, been skirting around the concept for a long time of a full displacement hull... always keen try and master something different.