Re: mercury propeller
Welcome aboard rgs!!
The numbers are diameter and pitch. Diameter is somewhat obvious, but pitch is a little confusing to some.
Pitch is the theoretical distance a propeller would travel through a solid in one revolution. Imagine a corkscrew into a cork. When you turn it one revolution it would travel a certain distance. Think of a prop in the same manner.
In reality you are turning a propeller in water and it will not go as far as it would in a solid. The difference between this theoretical distance and what it actually does through water and pushing a load is slip.
Slip is expressed as a percentage and it would be common to hear of around 12% so a 12 inch prop may only travel 10.56 inches through water depending on a bunch of other factors.
We would need more info to answer your question, you should read the stickies above and peruse this section and you'll begin to understand this piece of boating that is best described as voodoo . . .
