I was slightly nervous about entering Ashted Tunnel on the Digbeth Branch on the BCN recently. The last time I came through was on Shadow, going down the flight of locks. On that occasion, despite hugging the towpath, the "offside" handrail scraped the tunnel wall. Matters did not improve when a following boat sent a lockful of water into the pound!
This time, though, going the other way, we had no such problems. Andy held the boat in to the towpath, but I had, ooh, an inch or two to spare.
Actually, the bits which came off the worst on Shadow were the side fender ropes and the corresponding eyes in the handrail (fenders not deployed, natch). Jubilee has a better system, in that the fender-securing eyes are in the gunwales.