The combined ticket, which Primus-Linie and Rhein-Main-Verkehrsbund (RMV) offer jointly, can be purchased for Primus day trips in two versions.
With the standard version passengers travel with Primus boats to their destination and location of return (e.g., Aschaffenburg, Seligenstadt, Rüdesheim, Wiesbaden/Mainz). There you can take the train for the return trip, provided that you bought a combined ticket.
The second version, the extended combined ticket, works the opposite way around: passengers purchase this combined ticket in advance (or on the day of travel at the Primus-Linie ticketing kiosk), travel by train to their destination or location of return (e.g., Aschaffenburg, Seligenstadt, Rüdesheim, Wiesbaden/Mainz) or other landing stages of the return route and travel back by boat. The return trip with public transportation from the dock to your home within the RMV region is included in this ticket.