Loc: near Yosemite in California
I found this on another forum (I hope this is where you are in the game):
Do you have a flare gun?
Click to reveal..
Use the flare gun to shoot down the wire cutters hanging near the wench which you use to pull the boat in. The wench needs a new belt, but look up at the wires overhead. You'll see where someone has tried to cut the wire. Those wirecutters will come down if you shoot them with the flare gun. Cut the wire in the shack and use it to get the boat key in the church box.