trolling motor prop

[egreen024]

got a 67lbs trust motor guide, and it has a 3' ninja 2 blade prop on it, I want to get a new prop since this one is very dull, my question is, do I have to replace it with another 2 blade 3" prop or can I put in the 3.5" ninjas on it, and is there any advantage by going to a 3.5? could I put a three blade? and again is there any advantages of doing it? the boat is a ranger r80 with a 150.