Repair busted Futures fin box using pour foam

Discussion in 'Surfboards and Surfboard Design' started by Mitchell, Apr 1, 2018.

  1. Mitchell

    Mitchell Well-Known Member

    Jan 5, 2009
    Finbox was completely tore out of blank with BIG chunks of the foam removed to get rid of all of the bad glass and foam chunks. I would normally just use resin and q-cell for this type of repair, but decided instead of adding all that extra resin, it made more sense to replace a bunch of missing foam with foam.

    Fin removed and hole in board prepared for replacement:

    Hole filled with 3 lb. density pourfoam. This stuff expands a LOT!

    ....and sands down flush easily.

    sanded pour foam painted to match the board...or so i thought:

    Futures fin slot routed in the foam. I spent a LOT of time measuring the location from the other front fin. BIG ISSUE...i knew it was coming but it was worse than i thought...the router jig is really made to sit on a foam blank and stay in place Sitting on a finished surfboard it just wants to slide around when the router starts vibrating. If the jig moves even a little while your cutting the slot, the repair just went off the rails. I ended up clamping the jig to the board with big wood working clamps. I was very glad when this step was done.

    new fin box ready to set in with resin and a bit of milled fibers to thicken/strengthen:

    New finbox set in with the resin/fibers:

    fin slot taped off and area masked off and glass patch (2 x 4 oz.) set up:

    By this time its obvious the paint (which matched initially) is darker with the resin over top. I guess i knew colors darken when glassed, but oh well.

    Few steps compressed here, but the lamination was feathered, then hotcoated, then sanded out and feathered to the surrounding board. The more sanding out, the more obvious it is that the paint was too dark.
    nopantsLance and capecodcdog like this.
  2. DawnPatrol321

    DawnPatrol321 Well-Known Member

    Mar 6, 2012

  3. La_Piedra

    La_Piedra Well-Known Member

    Oct 9, 2017
    Joe Roper would be proud, very nice work.
  4. Mitchell

    Mitchell Well-Known Member

    Jan 5, 2009
    thanks! I just hope it holds up. The board belongs to a guy who is tough on his equipment. I think I've repaired snapped noses on at least three of his boards.
  5. Barry Cuda

    Barry Cuda Guest

    Serves you right for having that gay palm fin.......
    mudpuppet likes this.
  6. soulrider

    soulrider Well-Known Member

    Jul 19, 2010
    I like that tail block... looks fun.
    Awesome job on the repair!
    Color matching is hard, especially for me (I’m color challenged).
  7. La_Piedra

    La_Piedra Well-Known Member

    Oct 9, 2017
    Yeah but he makes up for it with those cool dagger to the skull fins.
  8. Mitchell

    Mitchell Well-Known Member

    Jan 5, 2009
    I doubt Barry will see it that way...there seem to be very few things that don't trigger thoughts of gayness.
    La_Piedra likes this.
  9. Barry Cuda

    Barry Cuda Guest

    That's gay......
    La_Piedra likes this.
  10. Mitchell

    Mitchell Well-Known Member

    Jan 5, 2009
    haha didnt see that coming
    Barry Cuda likes this.
  11. Mr.Belmar

    Mr.Belmar Well-Known Member

    Aug 19, 2010
    NICe job!!

    Those color matches are the hardest ... you got it as closer then many others would have... looks nice!
  12. headhigh

    headhigh Well-Known Member

    Jul 17, 2009
    you made that look way too easy ha
  13. capecodcdog

    capecodcdog Well-Known Member

    Jun 22, 2012
    Mitch, nice informative post. Sooner or later one of our borts will suffer a broken fin box. I once fixed a box that was ripped out and dangling, but did not have pour foam. My "rookie" fix was functional but ugly. Yours looks great. I'm not sure how you'd match the color perfectly, unless you played around with different paint tones on a sample piece of foam, and then glassed it, to see how dark it ended up, which would be a bit time consuming. Anyways, I'm sure the dude was very happy with the repair. Thanks for sharing.
  14. La_Piedra

    La_Piedra Well-Known Member

    Oct 9, 2017
    I can do everything but router the fin box lol.
  15. Mitchell

    Mitchell Well-Known Member

    Jan 5, 2009
    yeah on that i got really lucky. About 15 few years ago i ordered a new longboard from a local established shaper. He knew i was getting into making making a few boards for myself and gave me his old metal jig for a big plunge router, and the two Futures router bits (for the 1/2" and 3/4" rear and front fin boxes). He had upgraded to the way better futures install kit that just uses a small trim router and much more user friendy jig.

    15 years later his gift is still giving, and i'm still buying boards from Jon Ashton.
    nopantsLance and La_Piedra like this.
  16. JayD

    JayD Well-Known Member

    Feb 6, 2012
    Looks very professional. Quality work man. I'm wondering though...b/c I don't have the patience lol to ever do that myself, could you (or me...looking for a more efficient route, knowing I'm probably giving up strength) just pour resin in hole and brush resin around foam still stuck to original fin box and put in place with pressure? Maybe cut away some existing glass around perimeter. Once cured come back and glass coat it then sand? Your way is the right way, just wondering if my quick route would survive or be a waste of time? It would probably be challenging to get box flush with bottom. How long did that take you?
  17. Mitchell

    Mitchell Well-Known Member

    Jan 5, 2009
    Basically, yes. I've replaced futures fin box blow outs where i just stuck the same fin box back in the hole with resin and maybe some chopped strands to kind of toughen it up. Fill it up with resin to flush with bottom surface. you really should glass a couple of cloth "football" patches over finbox though. That way would take a fraction of the time of this repair, and if it were one of my boards, especially one that was already well used, and one that was plain white so no paint or resin colors to fool with, its pretty much how i would do it.
    JayD likes this.
  18. Mitchell

    Mitchell Well-Known Member

    Jan 5, 2009 was a board i shaped for a friend.
  19. CJsurf

    CJsurf Well-Known Member

    Apr 28, 2014
    I just replaced a futures box last week that was ripped out pretty similar to the one in the OP. I used resin thickened with micro-balloons to the consistency of peanut butter. If I did it over I would have gone even thicker with the resin mix. It was a clear board so matching colors wasn't a worry.

    My only worry with the 4 pound pour foam would be that it might not hold up over time with the side to side pressure on the fin as the 4# pour foam isn't as tough as the surfboard blank. I think if I were going to use pour foam for this sort of repair I would go with the 8# density foam. I use 4# foam from the same supplier for boat projects and once you get through the top skin the foam itself is pretty soft. I think the way the Futures box ties itself to the fiberglass skin of the board will help a lot though in keeping everything stable. I think if this repair were done this way on an FCSII box I think the 4# foam would almost certainly fail. That flange on a futures box really ties things together nicely.
    Last edited: Jul 7, 2018