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Re: Fin box repair

Posted: Wed Jun 26, 2013 12:10 am
by jbdc
While I'm an epoxy repair novice myself, I recently had to do a fairly significant repair to what I thought was a small rail ding, which turned out to be much larger than I thought:

https://drive.google.com/uc?export=view ... zdzYUlXMjQ

After sanding it down, it looked more like this:

https://drive.google.com/uc?export=view ... lJyc2xDWVE

And it was spongy under the entire area about 1cm in from the edge of the outline. It needed to be cut out:

https://drive.google.com/uc?export=view ... lYzb2lOY0k

I then filled it with 2 part epoxy and Q-Cel (3M Micro Bubbles will work too), sanded that down, did the laminate layer, more sanding, then a 'hot coat' (at least as much as one can with epoxy). I'm not gonna lie, it was a lot of research, sourcing materials and work; but I'm happy with the result.

If the box is moving 2mm, you might have a bunch of crushed foam with voids under the laminate like I did. Your best bet is to sand down to the glass, then you'll have a better idea of what sort of repair you're looking at and it won't screw anything up if you need to take it to a shop.

If the fin box needs to be re-seated, you're probably best taking it somewhere for repair if you can; they'll have all the equipment and materials to do in a few days what will take you a couple weeks after work and on weekends trying to find places that have clear epoxy and weird fairing compounds.

With all due respect to chipmunk, I don't know how he can so confidently assert a plan of action without having seen the damage in person.

Re: Fin box repair

Posted: Wed Jun 26, 2013 1:06 am
by tautologies
jbdc wrote:While I'm an epoxy repair novice myself, I recently had to do a fairly significant repair to what I thought was a small rail ding, which turned out to be much larger than I thought:

https://drive.google.com/uc?export=view ... zdzYUlXMjQ

After sanding it down, it looked more like this:

https://drive.google.com/uc?export=view ... lJyc2xDWVE

And it was spongy under the entire area about 1cm in from the edge of the outline. It needed to be cut out:

https://drive.google.com/uc?export=view ... lYzb2lOY0k

I then filled it with 2 part epoxy and Q-Cel (3M Micro Bubbles will work too), sanded that down, did the laminate layer, more sanding, then a 'hot coat' (at least as much as one can with epoxy). I'm not gonna lie, it was a lot of research, sourcing materials and work; but I'm happy with the result.

If the box is moving 2mm, you might have a bunch of crushed foam with voids under the laminate like I did. Your best bet is to sand down to the glass, then you'll have a better idea of what sort of repair you're looking at and it won't screw anything up if you need to take it to a shop.

If the fin box needs to be re-seated, you're probably best taking it somewhere for repair if you can; they'll have all the equipment and materials to do in a few days what will take you a couple weeks after work and on weekends trying to find places that have clear epoxy and weird fairing compounds.

With all due respect to chipmunk, I don't know how he can so confidently assert a plan of action without having seen the damage in person.
I think you are right. In general I think getting epoxy spread out where it needs to go is hard with only one hole...however it does depend on what the goal with the repair is..if the goal is get squeeze another few sessions out of a board then fine...if you want the board to hold for a long time than I think more is needed. To re-seat a fin box would for me be too much to ask..I would get a cross-eyed board.

Re: Fin box repair

Posted: Wed Jun 26, 2013 11:47 pm
by chipmunk
i have repaired and made boards for over 40 years :o
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Re: Fin box repair

Posted: Thu Jun 27, 2013 12:08 pm
by chipmunk
This is an old raceboard in my workshop hope it helps :naughty:
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the drill depth will be different on your board :thumb: then sand and glass the bottom :D

Re: Fin box repair

Posted: Thu Jun 27, 2013 5:20 pm
by jbdc
I guess that much experience explains how you can dispatch good advice on little information! :D

That's a great set of instructional photos. After drilling the hole(s) do you do a suck/blow test to see if the resin/filler is actually going to go anywhere?

Re: Fin box repair

Posted: Thu Jun 27, 2013 11:47 pm
by chipmunk
Yep old dog :lol:
More than 5ml you run the risk of over heating - but yes you can do it again and again till you are happy just drill a new hole this is to stiffen up the damage under the box and reattach the box back to the deck

After doing it you may need to put some epoxy into the holes to fill it up :D No need to test

Hopefully you will get the epoxy coming out under the tape you will see after it is removed but you will still need to sand it back and glass it up

:thumb:
some more info http://www.kiteboarder.co.uk/kitesurfin ... 65&t=36373

Re: Fin box repair

Posted: Sat Jun 29, 2013 3:40 am
by yojimbo
I ripped one of my fins right outta my board after a hard landing. I purchased this product:

http://www.ebay.com/itm/EPOXY-DING-REPA ... 3354a89457

and I bought some of these: http://www.ebay.com/itm/FCS-surfboard-f ... 56346195a0

and I watched this super chill video:

https://www.youtube.com/watch?v=BLgAVIm4Tvc

Re: Fin box repair

Posted: Sat Jun 29, 2013 1:31 pm
by chipmunk
Nice Video on how to put a box back in Yojimbo :thumb:

Never use Polyester products directly on to polystyrene foam this is Why
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Re: Fin box repair

Posted: Sat Jun 29, 2013 2:51 pm
by edt
chipmunk you are amazing! What do you use for replacement foam? I'm shaping a blank I got for free, and it has some gouges I have to fill not sure what to fill them with. Or do you just fill everything with epoxy + glass bubbles?

Re: Fin box repair

Posted: Sat Jun 29, 2013 5:51 pm
by chipmunk
If its polystyrene foam yes epoxy or you can try epoxy putty
http://vimeo.com/38680382 but a photo would help