We made two down wind runs today. The video was shot on the first run. On the second run, the wind hit 20 knots, but I didn't take the camera.
Jacky and I concluded the older board generates higher bust speeds, while the new board gets up to speed and holds the speed easier. The original (older) board is capable of a higher top speed than anything on the water we have tried. It's a rocketship, that constantly slams into the back of the next wave. That is the biggest challenge with the older board. How to manage the acceleration and keep the plane going. With the new board, it gets going easier, and keeps going easier, but doesn't get the turbo boost. In a distance race, the new board would win due to its ability to maintain speed.
Knowing exactly how these two boards differ in shape, I can make some assumptions about why this is. Although, I'm no expert, so I could be wrong.
The two boards tested today are the same width, same tail rocker and same nose rocker. But, how these rockers get from the tail to the mid point, and mid point to nose, is very different. On the new board, the rocker is more gradual through the middle, making it very efficient standing in the middle. To make a rocker more gradual through the middle, the curve must accelerate more to reach the total tail rocker value. The older board has a rocker more gradual in the area you stand at, when you take a step or two back. When you flatten the rocker "curve" back there, it makes the transition through the middle of the board more curved. Compromising performance in the middle, but increasing it a step or two back.
On the next board, I will tweak the rocker one more time and try to get a compromise between both boards.
Brian Autry, regarding the 12'6 racing class. All 12'6 racing shapes will be displacement within 2 years. I'd also guess the proliferation of displacement hulls 2 years from now, will cause a "surfboard" racing class to emerge. Just so the casual racer can show up with their surfboard, and not feel like they have to buy a race board to have fun. It takes about a year for the production boards to catch up and get displacement hulls in shops.
I think planing racing hulls will become a niche board, used in windy places. We'll probably see down wind races only become a reality in the traditional hots spots for windsurfers and kitesurfers, like Corpus Christi, Hood River, and Maui.