Need help with a fin box

Discussion in 'Surfing' started by Walnuts, Dec 11, 2019.

  1. garagefull

    garagefull Active Member

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    180
    Feb 22, 2004
    Santa Cruz
    Shaving the bottom of the tab usually fixes the problem. But I've had a couple of boards where that wasn't enough. I was afraid of taking too much off the tab and weakening it. So I added some material to the bottom of the fin and that took care of it. I mixed some milled fibers into the resin for strength. I've had this problem with a couple of Chinook boxes from the 90's. Almost every fin I tried in the Chinook box was loose. You can see the thin line along the base in this pic where new material was added.
    IMG_2451.JPG
     
    Driftwood likes this.
  2. dingpatch

    dingpatch Well-Known Member

    1,277
    819
    Apr 2, 2014
    Florida USA
    I'll add my thoughts later after I "get them together", LOL, BUT, , , ,

    I'm going through a "loose" fit problem with one of the fins I made right now. It seems that the range of "dimensions" of boxes is pretty dependent on which village they were made in.
     
    DJR likes this.
  3. Walnuts

    Walnuts Member

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    Mar 25, 2018
    Long Beach, NY
    Thanks everyone for the replies. I’ve been busy w work but plan to take a deeper look this week. Maybe I can add some tape to the bottom of the fin and if that helps as a test run will add some resin to it.

    @garagefull if I end up making this fin work you can have the volan one. Just pay shipping and we’re good. I’ll let you know what happens.
     
  4. garagefull

    garagefull Active Member

    359
    180
    Feb 22, 2004
    Santa Cruz
    Thanks, that is very generous of you!
     
    DJR likes this.
  5. SeniorGrom

    SeniorGrom Well-Known Member

    2,858
    1,496
    Mar 20, 2012
    USA New Jersey
    There is a lot of good insight on here and not always easy to tell exactly which dimension is the culprit. You add to all this the fact that some change fins a lot never rinsing or cleaning fins or boxes. The abrasive quality of a box full of sand will change things after just a few fin exchanges. In my opinion almost nobody pays attention to this. The location where the stainless split pin hole is drilled also determines how close the fin base will be to the bottom of the box when installed. Lots of variables.

    PS: There are depth tabs on the sides and ends of new FU boxes. This SHOULD be a no brainer for the installer to achieve the correct depth EVERY time.
     
  6. DJR

    DJR Active Member

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    Feb 1, 2018
    Carolina Beach NC
    That made my day
    For real
     
  7. Sax-son

    Sax-son Member

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    46
    Nov 23, 2019
    Three Rivers, CA
    There were a lot of non standardized fin systems that came out over the years. From that picture, it looks like a fin that came out in the early 1970's. That box looks like a regular Bahne box so I would look for a different fin for it. The fin you have looks like it would be hard to find a proper box let alone the work needed to install one.
     
  8. Walnuts

    Walnuts Member

    66
    36
    Mar 25, 2018
    Long Beach, NY
    So, just to clarify, thats the fin that came with the board and fits perfectly. I am trying to put a Greenough 4a in there, which is brand new.
     
    SeniorGrom likes this.
  9. SeniorGrom

    SeniorGrom Well-Known Member

    2,858
    1,496
    Mar 20, 2012
    USA New Jersey
    Wow we took this far afield! It’s very very simple just beef up the sides of the 4A with any of the suggestions (layers of tape, business cards, permanent glass layers etc.) until it is snug and flexes with no slop at the base. Then go surf the board. Geeez at least this was a really good seminar in box, fin fit.
     
    Sax-son likes this.
  10. Sax-son

    Sax-son Member

    44
    46
    Nov 23, 2019
    Three Rivers, CA
    I would take it into a surf or repair shop and see what fins will fit into the box. If you find one that works well, see if that manufacturer offers a Greenough 4A or similar. Some fins fit snug and others can be a bit loose in the box. It's not exactly rocket science, but I have usually been able to remedy the problem without too much hassle.
     

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