British canals are smaller than you imagine, and were even when they were commercial waterways. The standard lock widths are only 7ft or 14ft (2.1m/4.3m) so the boats are narrow, proportionally long, and very small compared to a Rhine barge or something.
As with the railways, we built early, to a small gauge, and lived with the consequences of that later.
There was a big canal bank collapse in December, and you can see in news photos the drained bits of the canal around the hole. The boats sitting on the canal bed are barely lower than they are normally when floating. Looks like 4 feet deep.
As with the railways, we built early, to a small gauge, and lived with the consequences of that later.