Crack around finbox: advice please

[singingdog]

Noticed a crack around the finbox on my touring board. I must have hit a rock that I don't remember. The box is still firm, no wobble or movement that I can discern. Normally, I would repair this with mastic epoxy. Any advice is appreciated.
1. Can I just patch this, or should the box be removed and reinstalled?
2. If patch is the way to go, is mastic epoxy the best choice?
3. Best way to make sure that the inside of the board is dry before patching?
Thanks.

[Weasels wake]

Patching that crack will never work, when in use the fin will want to flex side to side, even on a brand new board w/ a brand new box, nature of the beast.  That box must be routered out and replaced with a new box, and that process is a whole discussion in itself.  But to keep this post of mine short, go here for box replacement advice.   http://www.boardlady.com/repairmenu.htm

[Bulky]

That brings back memories.  I had a really troublesome leak that looked really similar.  Mine was actually brought about by sun damage where the little slice exposed by the slot in my board bag had disfigured and overtime a hairline like that developed.  I suspect yours may also have developed over time and wasn't something traumatic you would remember.  Do you use click-in fins?  These can expand a hairline crack steadily over time.

Unfortunately, probably nothing other than replacing the box will fix it for good.  I went through the progression of easy fixes--trying to fill with some epoxy and then lapping some glass over the area.  But they eventually failed as that crack always came back.  Finally had to go for a full replacement of the box.

The professional way to dry out a board is with a vacuum pump.  That's the best way if time is of the essence.  My backyard way is to put the board out in the sun and just see if moisture starts to bubble out--doesn't take long on a sunny day.  From there, it's certainly risky to dry boards out using the sun (especially if it's carbon--but I've done it).  I've also let it sit in the warm rafters of my garage for a week--and then repeating the sun test.  Could take a long time if you've got a lot of water in there but I imagine that wouldn't be the case with a skinny crack like this.  But then again, if you're going to replace the box (like WW also says) you can just open the board up and give it some time to dry out whatever may be left after you remove material.

[seadart]

I've been  patching up some fin boxes lately. Not an expert at fin boxes but have done a lot of board repairs.   You can let the board heat up in the sun for several minutes, if you start having moisture coming out of the cracks at a pretty good rate you probably would be better off to cut out the box and install a new one. If very little moisture you could do a temporary fix, with epoxy putty and glassing over,  but I don't think that will be the case.  When you cut the box out, you will have a better idea of how saturated the foam is, you need to remove a little glass around where you will install the new box and that will help the board dry out.  I would say from cracks like that, it will take at least a week to dry out after you pull the box.

[clinto]

SingingDog. I went through this exact situation a few weeks ago. After going back and forth on how to fix I decided to replace the box. It was explained by many on this website that no matter what, you have lost the strength in the box and it takes alot of pressure when you ride with a decent sized fin. I did my repair without a router and it turned out fine. Getting the old one out was the hardest part. You can see my process in this thread. The box repair starts page 2.

https://www.standupzone.com/forum/index.php/topic,31323.0.html


Its not the prettiest but it is strong and done right.