I actually owned a Holmsey Sidewinder, the original from which that board was designed off of.... I owned the Holmesy back in 1967-8ish. Great nose rider, for which it was designed. Holmesy only made 2-300 of them; wish I still owned it!!!
Yes, the sidewinders scoop and channel water on top of the tail, providing counterbalancing weight to nose, allowing for longer rides on the nose. Did it work?? Yes, but...it was the slowest longboard I ever owned, which is why I sold it. Noseriding was out. and shorter boards were being introduced. Times were a'changing....
To this day I still slightly concave the tail on my noseriders. I keep the rails soft, with no edge whatsoever, so water wraps around onto the deck in the tail, but without the drag-inducing irregularities of the notches.
