[PaulK]

If scarfing the repair into the hull would make the repair too big, perhaps you can simply fill in the hole neatly and put a big backing block – similar to a butt block used in carvel planking – on the inside. Do note that the scarfing ratio is based on the thickness of the plank you’re scarfing in to. If the hull is 1/2″ thick, the scarf would extend out 4″ from the edge of the hole if you’re working with an 8:1 ratio. Do note that, according to Google:“Traditionally, scarf ratios have been driven by the location of the scarf: 4:1 for planks, 6:1 (possibly 8:1) for keels, and 12:1 for spars.” If you make the repair with epoxy instead of wood, the ratios may be different.