The calculated distance (air line) between Seen (Kreis 3) and Schaffhausen is approximately 17 miles respectively 27 kilometers.
By car or train, the actual journey to Schaffhausen is certainly longer, as only the direct route (as the crow flies) between Seen (Kreis 3) and Schaffhausen has been calculated here.
Air line (approximately)
27 kilometers
14 nautical miles