Jerome is fond of locks; why?

Jerome is fond of locks because they provide relief.... you can sit back and enjoy the scenery, indulge in conversation, or gossip with other boaters.

From the text:

For myself, I am fond of locks. They pleasantly break the monotony of the pull. I like sitting in the boat and slowly rising out of the cool depths up into new reaches and fresh views; or sinking down, as it were, out of the world, and then waiting, while the gloomy gates creak, and the narrow strip of day-light between them widens till the fair smiling river lies full before you, and you push your little boat out from its brief prison on to the welcoming waters once again.

They are picturesque little spots, these locks. The stout old lock-keeper, or his cheerful-looking wife, or bright-eyed daughter, are pleasant folk to have a passing chat with. You meet other boats there, and river gossip is exchanged. The Thames would not be the fairyland it is without its flower-decked locks.