Future fin fix suggestions


Looking for some suggestions from the sage members of this amazing forum.  Or maybe even a “snap out of it, stop over thinking, and get on with it”.  I have routed out a future fin box It was taking on water and the fin was obviously moving under the very precise wiggle test.  

It was going pretty well, dropping the router 1/16- 3/32 or so each pass, until the last pass which grabbed and pretty much negated any of the careful steps I had taken previously.  The foam seems to have very little integrity at this point.  Besides the obvious ratty looking appearance the foam is cracked and moves near the outside edges of the upper route.  (I KNOW SOME OF WILL SAY THAT BEING DOW IT DIDN"T HAVE ANY INTEGRITY TO BEGIN WITH.  BUT IT IS AND I WANT TO FIX THE BOARD!)  The Dow is my fin box insert because the board is 1lb eps.

So should I just throw another box in there glass over it and be done with it.  Or fill with some other substance(more dow?, epoxy/cabosil?, pore foam?) reroute and glass.  What say you o wise Ones? 


Thanks for the help.






Short answer; use milled fibers and a couple layers of 4 oz. and put the box back in. Glass over.

Long answer: Rout out entire mortise larger than box, put in divynicell of other hard foam “dutchman” and start over with the box mortise. Then glass over.

Fix it like you never want to do it again.  Route out the hole clean.  Epoxy in an insert.  If you've got some pu foam cut offs use that. 

I agree with DMP, and I wouldn’t rout the hole any wider just make an insert to fit the existing hole, then re-rout the insert w/the futures jig. don’t know how much it might help but if the boards not real thick there maybe carefully rout deep, try to get the new PU insert & epoxy to contact the underside of the deck skin. Probably overkill but if you’re using big fins you could beef up even more by doubling up on the (small over large feathered in) football patches.


nice clean work by the way!