The file consists of correspondence between the Engineer to the Humber Conservancy Board (Arthur Ernest Butterfield until 1946, then Ralph John Hindmarsh) and various suppliers of echo sounding equipment for use on the Board's motor launches. This includes correspondence detailing poor performance of some of the supplied sounders, and 'Justification Reports' calling for the replacement of some of the older units.

Another report included within the file details a survey of King George Dock, carried out by the Superintendent (Upper Humber), on 29 June 1948 using echo sounding equipment.