Hi, whilst reversing recently, I hit something underwater with prop. Felt like something hard, like a small log, or maybe a fender. Anyway, took it out of gear straightaway, let it settle and then engaged slow forward, fine no problem. I was stopping for fuel etc. Anyway after starting up again I have got this tiller shake like something is on the prop. Stopped again looked at prop just some rope, which I got off, and continued journey, but no change continues to shake like something on prop, or low water level. As I was returning way I came, and hadn’t noticed the vibration earlier, that was a week ago, still getting this vibration. I know at this time of year , leaves etc, but it is continuous , I am wondering could I have damaged something. Propeller seems stable. What should I check for, if anything ?