The calculated distance (air line) between Burg auf Fehmarn and Gadebusch is approximately 51 miles respectively 82 kilometers.
By car or train, the actual journey to Gadebusch is certainly longer, as only the direct route (as the crow flies) between Burg auf Fehmarn and Gadebusch has been calculated here.
Air line (approximately)
82 kilometers
44 nautical miles