I had a similar event.

1. I cut a rectangular hole around the damaged area (square corners, but oval would also work - circles will not).

2. Cut a rectangle of ply about 3/4 of an inch larger than the hole all around.

3. sand inside the hole to key surface.

4. Drill small hole in your ply rectangle and put a knotted string through it.

5. Epoxy the overlap on your small rectangle and slide into the hole. position and hold ply rectangle in place by tensioning the string with a bungie or weight hanging down from string until glue is set.

6. Cut a rectangle of ply the size of your hole and glue it onto your new backing piece to bring the hull back to a fair surface.

This is the standard method of proper repair for small penetrating wounds in ply hulls. You will hardly notice the repair and if you wanted you could even create an ovalish design of some sort: an arrow or dolphin or whatever.

Etienne