How do I get the prop off my motor?  I can see it has a nut, but there is some sort of pin around it

hard to tell from the pic but it should have a snapring in it  you bend the tabs  up and remove it when you put it back on bend the tabs back down

Looks like one of the old merc's that use the locks on the back with the ears that fold down on the nut to keep it from coming off.  If so, take a sharp chisel of some you can tap down between the locking tab and the nut to get it away from the nut some, then something not so sharp to tap it on down flat so you can get a socket on it.

I agree with Way2slow. Looks like you have a tab lock type washer behind the prop nut. Bend the tabs back outwards and remove the nut. You may want to consider buying a new washer when you put the prop back on.

I'm the baitmonkey's brother.................Glockmonkey.

I make him an offer. He don't refuse.

I'm the baitmonkey's brother.................Glockmonkey.

I make him an offer. He don't refuse.

:-/ok