To be completely honest, I'm not sure when or how it happened. We were at a small lake in Canada for couple of weeks and I didn't notice the damage until we pulled the boat out of the water to go home. It could have happened when someone was climbing in or out of the boat (even though I discourage people from stepping on the outdrive) or it could have been when I was teaching one of the young ones to dock the boat (we had a few bumps from itchy/inexperienced/spastic throttle hands), or maybe we hit something floating in the water. I really don't know.
From what I've read here, it looks like something a prop shop should be able to fix without too much trouble.