Football patches are fiberglass patches shaped like footballs which are used for strengthening pre-glass fin systems, such as FCS Fusion, FCS II, and futures.
They are laminated over the fin boxes at the same time you laminate the bottom of the board. The football patches go on first, then roll your bottom fiberglass over them.
Use 4 oz. scrap fiberglass (you can use 6 oz as well) Cut it out about 1" bigger on all sides than your fin box shape into an oval (or football shape) and lay over the fin box. MAKE SURE YOUR FIN BOXES AND SCREWS ARE TAPED OVER FIRST!!!Then roll your bottom fiberglass over and saturate with resin. Pull out any excess resin from the fin box area and pop any air bubbles around the fin box holes.
NOTE: if you are doing an opaque pigment bottom lamination, it is best to route and install the fin boxes after the lamination so you can see them. Then the clear fiberglass football patches go over the fin boxes and bond to the lamination - giving the fin boxes more strength.