My old Columbia 26 had the same arrangement, and came with a fiberglass cap to cover the bottom of the hole. There was a matching cover for the top, and a bungee cord held them together. I guess the idea was you could pull the motor put and temporarily mount the cap. Actually saw that done in a movie about a voyage in the same model boat.
We put the OB on a transom mount too, and glued the cap on with 5200. (Could be removed of you really wanted to, but wasn't going to fall off by itself.)
Lacking a pre-made cover, I'd tape a piece of heavy cardboard in place to form a mold, and lay in a few layers of glass from the inside. You could make it removable by covering the hull with clear packing tape first, or just bond it in to be permanent. I like the idea of making it a cooler or bait box.
We put the OB on a transom mount too, and glued the cap on with 5200. (Could be removed of you really wanted to, but wasn't going to fall off by itself.)
Lacking a pre-made cover, I'd tape a piece of heavy cardboard in place to form a mold, and lay in a few layers of glass from the inside. You could make it removable by covering the hull with clear packing tape first, or just bond it in to be permanent. I like the idea of making it a cooler or bait box.
