Question about 4 stroke small propellers and gear cases

[fastback4]

I've been looking at 60hp Mercury 4 strokes for an upgrade and i've noticed the lower units are skinny and the props are very small or at least they appear to be. Now i've been running a 1999 2 stroke 60hp Mercury for 8 years and it's lower unit is big and beefy with a large prop. I swear i don't think the prop on the 2012 Merc. 4 stroke was bigger than 10" across if it was that...Why so small?

[boats.net]

The propellers vary on the application and use of the motor. The largest diameter prop recommended for a 60hp standard Mercury is around 12.5 inches. The Bigfoot model 60hp Mercury can accept up to a 14 inch diameter. Usually the smaller diameter props have a larger pitch and the larger diameter have a smaller pitch. These are all rough estimates, but as you can see don't be too concerned with the propeller sizes.

[fastback4]

Good lesson, so i won't be concerned with prop size and pitch....Still doesn't an aluminum vs. a steel prop serve better to protect the lower unit from breakage should it collide with a stump in the water?

[boats.net]

Yes, an aluminum prop is recommended if the boat is being used in water known to have debri. The aluminum will give before destroying your lower unit (in most cases, not always).