What is this and could it cause vibration?

I recently purchased an Air Nautique 220 Team Edition with 37 hours on it. My first day out on the lake I noticed a vibration in turns when I had Perfect Pass set to 20MPH and the engine RPMs went up to maintain speed in the turn. I have no idea what would cause that. The prop and driveline look pristine. When I opened the engine compartment I found a pieve of plastic resting on the steering linkage that was about 2 feet long, 6 inches high with 4-5 serrations on top. Can someone shed some light on what the piece of plastic is and possible causes for the vibration?

Problem solved! It was a bent prop. I have no idea what I hit, but no doubt about it being bent. I was told it can be repaired as opposed to being replaced. Anyone out there have any experience with a repaired prop?

As for the plastic piece, apparently it goes in the gear tray above the engine and must have fallen down. Mystery solved!