We have a twin with unprotected props. We came up the Hudson and west on the Erie Canal in early May last year. There was lots of debris, so much that even though we were keeping a close lookout, we hit many times. We could feel it all the way up on the bridge. On the TSW in Canal Lake the weeds were so thick we almost got stuck, and the day before us a boat did get stuck and had to be towed out. During the thick weeds we felt a strong hit and I knew we had damaged the props. After getting out of Canal Lake we had a bad vibration. Called ahead and scheduled a haul out to swap out the props. We got to Big Chute and in talking to the lock master about the weeds, he said he would check the props when got up out of the water. He said the props looked ok but we still had weeds on the shafts. They went under and cut the weeds off. Vibrations were then gone. Haulout was cancelled and we saved $480 Canadian. This fall after we hauled for the winter, I checked the props and could not find any damage whatsoever. In all I would guess that we hit logs about 15 to 18 times and no damage. So much about twins not having prop protection. We do have a deep keel which undoubtedly helped.