Some years ago, I had a 15'' plywood catboat tied up in a marina along side the sea wall. It had three stays supporting the mast. Lightening hit  the top of the mast, ran down the stay to the SS rub rail, then along the rail to the lowest point of the sheer, then hopped from screw to screw down the side of the boat. It blew the top plywood layer off along two lines of screws, but because the bottom had been glassed, it did not sink the boat. No other damage was found.  I was so happy to have not been aboard! Leif Eriksson M17 "Corky"