thanks stephen thats great. just for the record too all of the boards with C-Drive and fcs break out the rear plug within minutes of surfing... not one fin solutions plug over 6 weeks of solid surfing! http://www.feraldave.com
STL, Those are indeed end plates. On fins that I have seen with plates they also influence trim. Some people say they make great nose rider fins. feral dave, That fin looks like you can get alot of base drive out of it and plently of tip flex. I'd imagine it's a pretty smooth fin. Dev Gregory brought me a fin very similar to that a year or two ago.
A problem with endplates such as those is the extension of the length of flow around the foils/wings. In water, you have about 3 inches before the flow around the foils turns turbulent. Extending the baseplate of a fin beyond this range will not have a good effect of reducing flow separation - it will increase it. End plates might be a good idea if fins were 1 inch long, but generally fins are more than long enough already. There is a nice summary of hydrodynamics (published in 1969) here http://www.rodndtube.com/surf/info/Hydrodynamics.html -Dave http://www.blakestah.com/surf/
Blakestah, those old Surfer hydrodynamics articles have some errors. I wouldn't trust everything in there. But they are a good starting point. And they are a great example of how far the surfing media has fallen in terms of interest in the vehicles we use. Could you imagine a four part series on theory today in Surfer? Interestingly, True North surfboards is experimenting with a "Bi-Fin." A different effect but worth pointing out. Looks like a cool group of builders. Feraldave, how can we get your fins in the USA? Ordering some Fin Solutions plugs soon. Rob Olliges
Terry Hendricks is absolutely correct in theory, in some cases it is non-trivial (and wrongly) applied to the surfboard. He is a physicist, after all, and a neat guy (and still surfing regularly). The difficult part of writing something like that is making it all comprehensible to the layman. It would be neat to see a series of articles on the mechanics of surfboards. Why use concave or vee? What is the difference, mechanically, between a thruster and a twin-fin and a twinzer and a 5 fin and a singlefin. What do down rails do? Why do longboards catch waves easier? etc, etc A lot of these topics get discussed here, and I think it is great. http://www.blakestah.com/surf/
Hi Dave, so who made these things? check my other post. Greg W