I came across the problem where I had to remove a set old fin boxes, well didn’t “have too” but I wanted them gone. They were still intact in the board so ripping them out would not work. Everything I read in the archives said that I should use a router to rout out the box. I was worried about what kind of damage I would cause taking a router to my board, also I had a good bit of resin I had to cut through.
Instead I took a dremal tool and cut the fiberglass right outside the resin line around the finbox. With this cut I took a sharp kitchen knife and scored the foam around the box. This left just the bottom of the box still secured to the board. To finally remove the box I placed a fin in the box and wiggled and pulled it till the box came out. This left a very nice clean hole around the box and tore rather little foam.
I hope this might be of help to someone else, also any suggestions on how else to do this would be great
I’m doing the same with the clark foam, just putting some foam and resin back in to fill it. I’ve been saving some of my bigger rail scraps for just this type of event
I use a Dremel with a 2" diamond cutoff disk, and cut around the resin line. If it’s a long center box, I cut it crosswise in the center. I then use a 3/8 brad point drill and carefully drill just barely thru the bottom of the box in about 4 or five places. This step minimizes a big chunk of foam coming out with the box. After the box is out, if there’s any problems with the slot (too big, too much foam gone), I’ll make it larger slot with a router and put in a full foam plug. If the slot was OK, I just put in the new box using extra filler and chopped cloth around it (pigment this mess and use a second resin fill over it). I do use a strip of cloth underneath the box only, but not around the sides.