Fall of 18 I was cruising the lake and threw a blade on my 26 Q-IV just trying to enjoy a beautiful evening while no one was on the lake. Water was smooth and clean, was only running about 50, just suddenly started to vibrate real bad. The blade in the picture was the 27 Q-IV that came with my boat. we were comparing it to the 26 PM we bought to replace the other one. I really like the PM overall and may buy a 29. I guess maybe all blades just fatigue in time.