We glide gently under a bridge on our way to the next mooring spot. On the narrow canals, there is around 6" to 12" either side of the boat to the bridge walls, and headroom can be restricted. The most difficult is when the canal detours sharply to the right or left just before or after a bridge. Not only is visibility ahead poor but the angle of entrance and exit to/from the bridge mouths can lead to some interesting navigational manoeuvring!
