RE: Cutouts - fact or fashion
A very interesting discussion. While I'm really not qualified to comment technically how cutouts actually work, it's clear to me that they have gained an important significance as boards have gotten wider with shorter high aspect planing surfaces. I have to think that they are here to stay, but what gets more difficult to say with any certainty is what configuration is the best. I often wonder how scientific the result is, or whether some of the development is more intuitive and experimental in nature. I think it's fair to say that trial and error is an ingredient in the mix.
One thing missing from the discussion above is how turning is affected by bottom and rail oriented cutout relief, and how things blend with rockerline's influence. Also, there is a bit of a broadening of concepts at work here with influences at work with light wind slalom designs, especially since high speed turning becomes crucial to performance. It would be interesting to hear more about this and how the configuration of cutout concepts vary between formula and slalom influence respective performance.
Lastly, I thought I would be of value to comment on a portion the bottom design of the high wind B&J/wave boards that I have been using over the last 11 years. Although these boards include a number of unique bottom characteristics, the tail of the boards feature a cutout that is shaped as an arc that starts from the rails at about the half way point of the US type finbox and intersects the finbox down about 7.6cm from the start. So, the entire tail aft of the arc is cutout to a depth of about 1.0-1.5 millimeter. Not a real deep cutout by todays standards, but it still must be considered a cutout or relieved area. I should point that the tails are quite narrow. I guess one of the noteworthy differences or departures from what is being done today is that it emcompasses the tail as a whole rather than implementation of balanced cutouts on either side of centerline. Even though I can't comment on the science of the design, the boards work very well, particularly in strong wind and rough water conditions. Very playful in nature, yet tracking is smooth and controlled.