The bridge at Acle is quite large. It stands ten or twelve feet above the water for the whole width of the river. It's also only about five years old. The bridge at Potter Heigham is quite different. It's about six and a half foot above the water at the centre, and the sides fall away sharply in a half-circle. It's seven hundred years old and is the lowest navigable bridge on the whole river-system. We had to go through it and, sadly, we are required to use the free pilot service to go through, so we did so without incident.
In my youth, when my scout group used to hire half a dozen yachts, the traversal of Potter Heigham was quite a different matter. Sail power only, and (in the early years at least) no motor. There are, in fact, two bridges at Potter Heigham. The new bridge is about fifty yards upstream of the old one, and is only about twenty years old. For a long time, there was a railway bridge in this position -- one year it disappeared, and the new bridge arrived the following year. We would approach the old bridge under full sail at a reasonable speed and, ten yards or so before the bridge, we would take down the sails, drop the mast and pass through the bridge on momentum alone. Between the two bridges the mast and sails would go up once more to pick up a little speed, and then down again for the second bridge. It was quite a spectacle, and not a little unnerving for the helmsman. More than once we got it wrong.
Now, we moor up on the right before the bridge. The pilot gets on, we motor through the bridges, and then he gets off again. All the romance is gone.