what type of prop do i need?

[andrewfarmer]

I have a 1985 basstracker. 15 ft alluminum boat with a 1997 evinrude 20 hp on it. The boat runs and performs great when i am by myself. But whenever I put one other person in the boat.....the rear of the boat draggs the water badly. I have heard that his could be due to over propping.? I have a 10x13 prop on it now. I believe this is the factory style. I have heard that 4 blade props will correct this problem better than 3 blade props.? I am clueless though, any help on what pitch, 3 or 4 blade, any insight would be greatly appreciated. I would rather replace a prop than go wasting money buying a bigger outboard to try and correct the problem.