Keeping them honest: Nonsensical 'release' theory in Surfer Magazine buyer's guide.

One of the latest buzzwords used in surf industry slang is the term 'release'Unfortunately in their typically arrogant and sloppy fashion Surfer Magazine have been spreading misinformation about this term and about surfboard hydrodynamics via their surfboard buyers guide.In my opinion the 'yeahguys' of the surfing industry discovered long ago that brainless and nonsensical marketing works better than the truth for the simple fact that surfboard buyers don't want to think, they just want to sound and feel like experts.Here's the quote from the Surfer Magazine buyer's guide:"Release-The effect that allows water flow to be accelerated as it passes along a surfboard's surfaces. Causes of release are usually available in the second half (tail) of the board, through tail rocker, outline curves and trailing fin edge, and through bottom features which open up opportunities for water to move, such as concaves and channels. Controlled release (along with it's opposite- drag) is essential to successful surfboard design."OK so this sounds informative, well researched, authoratitive and intelligent, at least at a first casual glance.Unfortunately it is Absolutely Brainless Bunkum ( ABB ) and is therefore dangerous propaganda, or would be if it actually said anything comprehensible.Let's have a look at it. The heart of the problem lies in the first sentence: " Release-The effect that allows water flow to be accelerated as it passes along a surfboard's surfaces. "The idea that surfboards accelerate water flow backwards thereby driving the surfboard forwards is a very common myth. A surfboard does no such thing, it merely travels over and through the water, and is unable to project water backwards. In fact, the only acceleration of water which occurs as a surfboard moves through the water is in the opposite direction. . .. water is dragged along with the surfboard, this is Drag, not Release. . .it slows the surfboard down and is to be avoided as much as possible, it is not an advantage it is the bane of all watercraft designers and is certainly not "essential to successful surfboard design" The myth of accelerating water flow is based on the idea that by enclosing and directing water flow backwards a forwards thrust can be created, but in reality the best situation is merely to leave the water as undisturbed as possible and to drag as little as possible along with the board. . . . to accelerate the water forwards as little as possible. The "lets accelerate the water flow backwards" myth is one of the various venturi based myths are around which hold that by squeezing water flow it will project backwards better, In reality no water is projected backwards unless the surfboard has an engine powered pump !So the first pemise is completely wrong, and what follows is (inevitably) just as bad. Acceleration of water as a surfboard moves always causes drag. 'Release' in fact reduces water acceleration by allowing the surfboard to part company with the water it is sliding over as cleanly as possible, thus leaving the water where it was if possible rather than causing drag by having the water attached to the board as it travels forward.Acceleration of water flow at right angles to the path of the surfboard is called lift, and it is necessary and useful to produce it. .. . the production of lift produces forwards acceleration of water, this is drag and is a disadvantage. No backwards acceleration of water flow occurs at all, and 'release' is merely a reduction in drag due to LESS acceleration of water via a clean wake and water flow exit.One of the reasons why the annular wing tunnel fin is so low in drag is that it produces lift using a large volume of water which it accelerates only slightly, unlike flat plane fins which work on a smaller volume of water and accelerate it more.