If you are installing a new propeller, it is always a good idea to spin it by hand before taking it out on the water. 

One reason is to verify that the prop fits properly into the gearcase and doesn't bind up when it turns. This could be due to getting a prop that isn't designed to fit your motor, having the wrong hardware, or the prop may have not been made to proper specs.

Another reason is to make sure that you are not getting any interference between the prop blade and the trim tab anode.

Many of the higher performance props being made today have more rake than the standard propellers people usually buy with their motors. This rake pushes the blade tips back further away from the gearcase and makes it more likely that the prop will hit a standard trim tab anode. 

We see this often with the following propeller models:

Mercury/Quicksilver: Tempest, Fury, Nemesis, Spitfire, Trophy, Bravo I

Powertech: PTR, VMX, VMS, TRO4, RKR, CFS, NRS, OSN, RAF, RXB

Yamaha: Talon, T1, T2

OMC: Raker

If you are running into this issue, there are a couple of ways to fix it. One is to trim the anode using a hacksaw or bandsaw, the other is to replace the original anode with an offset anode. We carry the Quicksilver offset trim tab anode which fits most Mercury's 35 HP+ and all Mercruiser engines. You can find it here.