Ouch!!! He was lucky a big ole bass didn't mistake it for some crank-bait.
Seriously, just turn your drive away from the swim ladder and use it to get back in the boat. Also, warn everybody that the prop is sharp and to stay away from it. One note however: I did all of the above and my father in-law still insisted on swimming around the prop and he kicked it with his shin. Yep, deep cut and a beautiful day shortened. Sometimes nothing you do can save someone from themselves.