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    Fins

    I thought I would bring this over here instead of jackin. Thread Jackin that is. Sheesh you guys are terrible.

    Starting with Surfdads last post, aaaaaand action!

    "Unless they are carbon, most of the fins are plastic and you can grind them down with a bench grinder. Jerry Price of Shred Stixx showed me once: Bench grind the rough outline and then the entry taper - then sand it with successively finer grits of sandpaper and finally use a wooden dowel to polish the whole thing - don't know why it works, but the wooden dowel gets rid of all the scratch marks.

    I would guess you could get a huge sb1 in like 4 or 5" and shape away."


    Here's why the dowel works or at least why I thing it works. The dowel is round and wooden. By the simple fact of it being round, all of the pressure placed on the dowel transfers to the fin surface at one small point. Wood itself heats up very quickly and by adding this little bit of heat and pressure to the fin, its just the right amount to smooth the surface without removing any material.

    I actually have used this in other applications, just never heard of it being used on fins. Neato. That's a nice little tid bit of knowledge right there. Thanks Surfdad. How fine of sand paper was he getting down to before breaking out the dowl? What kind of shape was he putting on the entry taper? Do you keep the inside edge fairly flat with a larger taper on the outside face. The 2 5/8" fins on my board are a foil, much like an airplane wing. The long surface is to the outside and the fins are "toed in at" the front. This should creat the "vacume" effect or actually pressure on the inside of the fin. That pressure applied to the "toed in" angle should create drive, no? So the goal here would be to generate the same amount of PSI in a significantly shallower fin (1 1/2" ~ o/a depth?) in order to help the revert ride. Hey whoa, how did we end up here again? Hmmmmm?
    You'll get your chance, smart guy.

    #2
    Hey Nick, that makes sense on the dowel. They smooth up really nicely, if you work it long enough they actually look polished.

    Off the grinder the fins are pretty rough. So, my routine is:

    Grinder
    80 grit
    150 grit
    220 grit
    400 grit
    1200 grit
    Dowel

    They shape pretty quickly, so it sounds like a LOT of sanding, but in reality maybe the whole process is 1/2 hour per fin.

    The inside always stays flat, or at least that's all I've tried in the larger fins. The base length limits the amount of surface area that's available. There is an excellent article on how fins function in Surfer magazine, I'll have to find it for you. The trail also has an effect on how the water flows and releases off the fin. Unlike wakeboard fins that maintain speed by being pulled by the boat, the surf fin is designed to generate speed that is faster than the surrounding water flow. MAN, we could spend a lifetime on this subject I do believe!
    Buy my kid's board! http://www.flyboywakesurf.com

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      #3
      Seems to me it's a good subject to delve into then.
      You'll get your chance, smart guy.

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