We're chatting in the living room with the harbor owner, when we spy some guy climbing over the gangway gate to the dock. Turns out he and his wife launched his boat, it was a no-go, and he eventually ended up in one of the empty slips. (he was climbing the gate to get back in)...
We go to find out what the deal is, and he starts asking if we know anything about props. Mark points to me---
Guy says he put the boat in the water but it acts like it's in neutral. Then he says "my son had the boat out last, and he banged up the prop so he put on a different one". He also explained he knows NOTHING whatsoever about props, engines, anything mechanical...
I went to the back of his boat, his drive was up, I grabbed the prop, it seemed to spin normally. I says "put it in forward". He reaches for the key... "you want me to start it and put it in forward?" ----"NO!" (yup, knows nothing!

)..."I just want you to push the stick forward with the KEY OFF." He does, and the prop still spins, but---feels different. "Ok, now put it in reverse". Same thing. Only I finally get the bright idea to grab the prop shaft. That's when I notice I can ratchet the prop shaft, but nothing from the prop. I ask him for a crescent wrench, and I pulled the prop.
Didn't drop anything in the lake either! Wonders never cease...
Wish I had pictures of what I found! What his kid had done was insert the center section of a Merc I/O prop into the hole of a Merc OUTBOARD prop! Those things take a much larger, square-ish center section that goes into the back side of the prop. But here's where Merc goofed---the center section of the I/O prop fits the hole in the OB prop PERFECTLY, so when you tighten the nut, the prop feels snug, and runs straight & true. But other than friction, there's no other connection between the prop and prop shaft. If Merc would've just engineered the OB prop with an ever-so-slightly smaller hole (or slightly larger center section of the I/O prop), the wrong center section wouldn't go in, and you'd know right away, something isn't right!
Anyway, kind of funny. I told him to ask his son where he found that prop...

I had him put his trailer in and I towed him over to it and helped them load up.
That was good deed #2 for the day. Good deed #1 was convincing a guy who'd bilge-pumped 30 gallons of gas into the lake after blowing a fuel line that it was NOT a good idea to just put more gas in it and start the boat! I still don't know how he didn't blow the boat sky high in the first place, as he was driving it the whole time the fuel pump was emptying the tank into the bilge! He only knew something was wrong when the tank finally went dry! And he tried starting it a few times before lifting the hatch...I'm not sure how he got into the harbor, he came in during one of our regularly scheduled storms, I guess someone towed him in...Anyway he had an inlaw fetch his truck & trailer from the other harbor and they loaded it up.
I'm not sure he realizes it, but I think it was his lucky day!