I would not suggest you tape that up. It would be a waste of money, time and materials. With current costs what they are, I could not afford to do it that way. Cut the most offensive panel out, put that back right for a lifetime, putty/tape in between them when that dries out. You can always cut the seam and do the rest right later. Don’t be afraid to screw down the old adjacent panel to solid stringers / frames if needed. Just fill fair and glass the holes where you have to add fasteners, if they are really needed. It will help the two stay together at the seam if they both don’t move much. You could go cheaper and use plywood with epoxy coated underside / two or so layers of 1708 on top. I would use epoxy if I was using wood as a core. My best advice, but I am sure there will be disagreement. That bad panel doesn’t even look glassed to begin with. I can see too many checks in the plywood showing through for it to have glass on it. Maybe that was coated with resin and gelcoat/paint? A fresh ply panel, stainless screws, non-skid, bilgecoat paint and 4200 might get you through the season quick and easy if you plan to pull it all up this winter. That panel is pretty important. Your scuppers are there. Depending on how your boat sits in the water, that seam could be a real sinking hazard.
