"rvbilly" wrote in message
ups.com...
Hi, I am not following what you mean with with the thrust bearing, and
what would be the advantage of the reduction gear? thanks Bill

When you turn the prop (pushing water aft) the shaft is forced forward. This
forward thrust must be transmitted to the boat through a thrust bearing:
http://science.howstuffworks.com/bearing3.htm

The reduction gear takes the higher input rpm of the engine and reduces it
down to a usable rpm so the prop does not cavitate. It also allows F N R.