Some props have the pitch and diameter stamped on them, some don't. SOmetimes you have to take the part number and find a guidebook.
Keep in mind that less pitch=more torque=more rpm at any speed. More pitch means the opposite. You could put on a prop that has too much and not get as much speed and not have the acceleration, and make it hard on your engine. Choose carefully. Ask for help if you don't know what you are doing.
I think the gentleman who has already answered made a mistake.
First less pitch gives more torque, and less speed. This is good if you are trying to get on plane quicker or pull waterskiers and such. You could also lower the pitch if your trolling speed is too quick. But on the bad side, you can also over rev you engine because if never has the full torque applied to the prop and do some serious damage at the top end.
More pitch is less torque and more speed. Great if you want to go fast, but it will take longer to get out of the hole with the larger pitch and if you go too much pitch I guess it is possible you may not get it on plane.
Props are best made neutral to the boat it is trying to push and you need to get help on how to change if it needs to be changed at all.
I just had to replace the prop on mine because I hit something on the bottom last Saturday and I had to get the marina to find out what ptich and diameter mine was becasue there was no numbers I could find on it. Good luck with your decision.
First off,You NEED to get a diameter and pitch Prop that will allow the Engine to reach full operating r.p.m.s!If you cannot achieve max.r.p.m.,s[assuming the Engine is operating properly!!]You will be putting Too much of a Load[strain] on the Engine,which is not good.If the Pitch and diameter are too small,You can over rev the Engine at WOT and not have the best Fuel mileage.Once you get a certain Prop. dialed in,you will achieve the best Fuel mileage.
NOW......All Props. are Not created equal!You can use 2 or 3 props with the SAME pitch and diameter and get totally different Performance and Fuel useage.Also playing with the Engine heighth on the Transom changes alot also.Been playin' with mine for about 2 yrs. on and off and almost have the optimum set-up.Just need to raise my Engine one hole and I'm done!Also,The same prop. may NOT react the same on different Hulls.[Mike]