Re: Do I need a new prop
Let's not over-react. If you knocked a little bit of material off the blade of an aluminum prop, I find it EXTREMELY unlikely you did any internal drive damage. Aluminum props are simply too soft.
If this is an Alpha, make sure you realize that they ALL click when you spin it by hand when in gear. This is by design and normal.
If in forward gear (engine OFF), you should be able to spin the prop clockwise, with rhythmic click click click click clicking as it rotates. And you should not be able to spin the prop counter-clockwise without a large amount of strength because you will also be turning the motor. If in reverse gear, you shiould be able to spin the prop counter-clockwise, with rhythmic clicking. And you will not be able to spin the motor clockwise without much strength, again because you will also be turning over the motor.
It should be quiet when you spin it in neutral. But if it clicks just a tiny bit when in neutral, it's usually becuase you might need a shift cable adjustment, but it's not catastrophic.
You can check for a bent prop shaft with prop removed, and a run-out gauge properly mounted.
If you were hearing noises after you raised the motor up to get out of the shallows, it's probably because you were running the motor with the U-joints in a bind and this tends to make some noise. And same if you are running the motor at home with the drive tilted above the normal trim range. You must ALWAYS have the drive in the DOWN position when running an I/O....whether you are in neutral/on muffs or not. NEVER EVER run an I/O engine with it tilted up beyond normal trim range...it can cause driveshaft/U-joint/Gimbal bearing/Gimbal housing damage. This is possible, if you have been running the motor for even a very short period of time while trimmed up into the "trailer" position too far.
People so often think you can use the trailer button to trim up an I/O beyond the trim range, in order to then drive out of a shallow area like it sounds like you may have done. This is usually a BAD idea as it can do driveshaft/gimbal damage. The damage has NOTHING to do with hitting anything with the prop, and simply has to do with that fact that every single rotation of the engine was slamming your ujoints into a very stressful bind while the motor was running with the outdrive tipped up. Sometimes people can get away with this without damage. Sometimes you cannot....
If you need to use the trailer button to get out of a shallow area, and want prevent this possible damage/excessive wear & tear, shut the motor OFF, then trim up all the way, then use an oar or rope or whatever to get the boat out of the shallows. Then trim back down, THEN re-start the motor and drive away. I/O's are NOT outboards, and they cannot be run in a "tilted" position without potential damage.
If any of this simply confuses you, just take it to your favorite marina, tell them what happened, and ask them if there is any damage. They can check it out for you and ease your fears. They might need to remove the outdrive from the boat to assess it fully. Or they might just be able to put it in their dunk tank and run it, and assess with their ears...
To directly answer your title question. Yes, you need to either replace the prop, or have it rebuilt/rebalanced (often $75-ish depending on your location). Either is an excellent alternative, again ask your marina for advice after they see the prop. Do not run a motor with a damaged prop.
