Another prop and prop question folks. Searched around the site and read a lot, but ultimately didn't find an answer for my situation.

I want to buy a replacement or spare prop for the Johnson 9.9 2-stroke on my Grumman Sport Boat, and I'm not sure what prop and pitch to buy. The prop that came on the engine is a 9-1/2 diameter with a 10 pitch. The engines runs good (no real idea of the RPM's, but it sounds good), and pushes the boat 10 mph with 600 pounds in it. I have no idea what it will do if/when I load it on up closer to 1000 pounds.

Obviously, I need a spare prop for safety/reliability reasons. I'm wondering if I should just buy another of what is on the engine now, or buy a prop with a different pitch for heavy load situations. (I'm not even sure that will work. If I break the other prop when lightly loaded, won't hte "heavy load" spare prop just lug the engine down anyway?)

The other issue is I would like to go to a stainless steel prop and that be my main prop. I could just buy a SS prop same as what is on there and have the old AL prop as a spare, but that eliminates the ability to have a "light load" and a "heavy load" prop. Yhen again, with a stainless steel prop, do I even need a spare prop?