The calculated distance (air line) between Burg auf Fehmarn and Bad Doberan is approximately 36 miles respectively 58 kilometers.
By car or train, the actual journey to Bad Doberan is certainly longer, as only the direct route (as the crow flies) between Burg auf Fehmarn and Bad Doberan has been calculated here.
Air line (approximately)
58 kilometers
31 nautical miles