Indeed JM - common sense!
Favourite fishing spots are around blind corners, boatyards (preferably at the entrance) 24 hour moorings (particularly like Rockland where there are few anyway)
Yet look at Oulton Dyke for instance or the Bure near Upton Dyke. There are fishing platforms on a straight wide stretch of river where fishermen and boaters could easily see each other and take avoiding action accordingly.
I can't say I've ever seen a fishermen smile either, particularly the ones gathered around Herbert Woods entrance