A couple of springs ago, during pre-season prep while our boat was still on her trailer, I had left our boat's front hatch closed but un-dogged. One day while I was just dropping something off, I spied the front hatch opening and a smallish raccoon coming out. It looked at me and then jumped across to the adjacent trailered boat. I went back on our boat and was about to unluck and remove the companionway boards when the racoon jumped back onto our bow. So I went forward and shooed it off again, but it was quite brave and didn't depart for the trees.
I went back to unlocking the companionway and entered to check for damage or evidence of nesting activity. Instantly I heard hissing from the quarter-berth and the source was ... two frigntened but otherwise Disney-cute racoon infants (kits or whatever they're called).
That seemed to explain everything. I left the companionway open, opened the hatch wide, and I spent about 40 minutes calmly explaining to her why our boat wouldn't be a great place for kids, and the momma finally removed first one than the other kit. It was quite something to see, and I'm kicking myself for not having a camera with me.
She carried the kits to a nearby small sailboat with an open cuddy, which was ok by me. I imagine that she bugged out of there at nighfall.
We were extremely lucky; apparently the racoon family had only spent one night aboard. Aside from chewing on some foam pads, and some racoon diaper-poo in a couple of places, there was no damage.