Someone searched my blog with the question: “Is it possible to switch surfboard fin boxes?” The answer is YES; in fact anything is possible. Anyone competent at surfboard repair can do it. If you want to do it yourself, it’s not too difficult.
Basically a fin box is installed by cutting a slot or hole in the bottom of the board and the box is resined in. There are some variations on this so be sure to get the box manufacturer’s recommended procedure for installation and follow that. Removal of the old boxes can be done a couple of ways: One is to cut around the old boxes and pull them out, and then repair those holes by resining foam plugs in and glassing a patch over the plugs (be sure to sand a taper on the surrounding glass — you want the repair to be as strong as the original glass job. You now install the new boxes per the instructions for a new board installation. The other way is to not remove the old boxes but to set-up a guide for a router as if installing the new boxes in a new board. In this case you are going to route out the old boxes (or part of them) just enough to install the new boxes and resin them in (epoxy is likely your best resin choice). In this case you do not need to make any repairs (unless the board had already been damaged).
If you decide to route out the old boxes, be sure to remove any metal (screws, plates, etc) before starting. Also note that the router will “bite hard” on the dense box so be sure that your guide is well attached to the surfboard and take a series of light cuts until you get to the depth desired. In most cases do not remove any parts of the old boxes that were outside the router slot, you’ll retain better strength for the new installation.
Finally, if a surfer is changing fin boxes, it’s probably a performance issue. In this case, were the original boxes in the correct location? I suggest you get my book “The Basics of Surfboard Design” and find out.