Fair comments.
The full story is that we went down the Arm, through the Middle Levels, nosed around the Great Ouse, Cam, Lark, Little Ouse and Wissey before retracing our steps back to the GU. That little lot took best part of a month. Perhaps it was the time of year, but that section of the Arm, together with very shallow sections on the Levels, around Whittlesey and March, meant that that section of the trip was, quite literally, a drag. The rivers were great!
So, perhaps I should rephrase - we don’t plan to do the Northampton Arm again in our current boat, but then we don’t plan to change boat!