Hit an alligator at dusk few years back. Didn't see it, but felt a thump and the back got loose. Looked behind me and saw a tail thrashing around. Realized it was wedged between boat and motor. Settled off of plane, got up to see it and it was gone. No damage to my boat. Waited a few minutes to see if the gator would show itself, but no. I was only doing about 35/40 mph. My guesstimate that it was only a 5 or 6 ft'er.