Rudkøbing is a city on the island of Langeland in Denmark.
It takes around 30 minutes by bus from Svendborg to Rudkøbing with Fynbus lines 911-914 (912 stops at the ferry terminal). They leave around every 30 minutes during peak hours, and every hour in the evening.
The port in Rudkøbing is open to both leisure sailors and commercial traffic, there are regular ferries to Strynø and Marstal on Ærø, look for Havnepladsen, 5900 Rudkøbing on your GPS if it doesn't include the harbour. Many buses stops at the ferry terminal as well.