Many years ago I got involved in bowhauling an engineless boat down a flight of locks. In one pound there were a lot of boats moored against the towpath, and in the middle of these a wooden centre cockpit cruiser with a raised wheelhouse over the cockpit. My mate was trying to flick the rope over this wheelhouse without success. As the boat continued to drift forward the rope caught on something on the wheelhouse. A moment later there was a load clatter and the wheelhouse collapsed into a heap of glazed panels and a roof at a drunken angle. We re-erected it as best we could, and beat as hasty a retreat as one can when bowhauling a narrow boat!