…you can sand the Fins Un boxes from top…a lot
I do that all the time, then cap with 2 or 3 4oz, H C then sand, then HC again then sand flush then all ready to gloss coat or speed finish coat
Howzit Jim, My trick was to punch holes on both sides of the stringer about half way down the routed box hole for and aft with a chop stick. Then when I mixed my resin I put milled fibers in it to give the resin some structual strength which would fill in the holes. This would extend the resin past the front of the routed box hole like fiberglass rods and take some of the stress from the board flexing. Seemed to work pretty good and never saw any stress cracks after using this technique, just thinking outside the box so to say. When it comes to thin tails I just route as much as possble and install the box since if the box is about 5" from the tail which is norm here hardly anybody set their fin all the way to the rear of the box.Aloha,Kokua
luckily for the retro craze guys who want their boxes 2" off the tail, the tails have the thickness to accomodate
Howzit Jim, The thing is if the board is a real retro 60's longboard it would have a glass on fin. Aloha,Kokua