Boat ride on the Rhine

The KD line is the one that does day trips.

https://www.k-d.com/en/

Most people recommend taking the train upstream to wherever you want to start, the taking the boat downstream. Going the opposite way takes a lot longer and the scenery is the same! In your case, Rudesheim is already “upstream” of a lot of the scenic areas, so you could hop on in Rudesheim, hop off wherever (Bacharach is a great stop) and take the train back. Make sure to study the timetable so you know if/when the boat arrives/leaves. It can be confusing.

Or you can stay on the boat as far as you want, then take the train back, stopping in the towns you want to explore. The train runs more frequently than the boats.

The Bingen-Rüdesheimer Company also operates various Rhine cruise options, including the classic trip from Rüdesheim downstream to St. Goar and St. Goarshausen (right across the river from each other. They offer 2 of these trips per day, one at 11 and one at 13:00 (which fills the large gap in the K-D schedule between 11:00 and 14:15.) B-R calls this trip the "Loreleyfahrt." Click on Loreleyfahrt at this page to see the schedule. See B-R cruise info and map of stops at the link below:

https://www.bingen-ruedesheimer.de/linienfahrten/linie/loreley-cruise

I don't have a preference for one or the other. Prices and service seem to be roughly the same. What matters is that there's a boat leaving R'heim at the time you want. However, if visiting Boppard by boat is in your plans, you will need to use K-D, as B-R doesn't travel further north than St. Goar. Alternatively, you can just get off in St. Goar and take the 10-minute train ride to Boppard from there, which might be preferrable anyway; the scenery north of St. Goar by boat is good but not better than what you've seen between R'heim and St. Goar. And the extra cruise segment does cost you a fair number of additional Euros as well as some time.

The west bank towns of interest include St. Goar, Oberwesel, Bacharach and Boppard. The east bank towns tend to be less popular (unless you're hiking the Rheinsteig trail - or taking the train from St. Goarshausen to Marksburg Castle in Braubach.) Whichever riverbank you're visiting, it's easier to town-hop by train... the boat schedule is skimpy and restrictive.

Note that the PASSENGER FERRY (which is not the cruise boat) is not functional at present between R'heim and Bingen. Normally you would use this ferry to get back to R'heim after visiting the west bank towns by train. So don't expect to cross the river there when you return to R'heim. Instead, use the St. Goar Ferry. It runs all day long and allows you to use the train from St. Goarshausen to return directly to Rüdesheim.

Thank you very much for this useful information!
We had already decided that we would be interested in taking the boat as far as St. Goar or St. Goarhausen, but weren’t sure which place it would stop. I noted somewhere that the stops are on the right or left depending on which direction the boat is going.

So you are saying we can get off the boat in St. Goar and take the ferry over to St. Goarhausen? Do you know if the train station far from the boat landing? Is there a bus in St Goarhausen that could get us to the train station?

Thank you!

The ship stops in St. Goarshausen, so you don't need to ferry across. The train station is about a 10 min. walk from the dock. It will be towards your left after you get off of the ship if you face away from the river.

"So you are saying we can get off the boat in St. Goar and take the ferry over to St. Goarhausen?"

Yes. The ferry (€2/passenger) shuttles across the Rhine all day long between the two towns, roughly 3 times per hour in each direction. The cruise boat will drop you in either town, but of course you'll want to get off in St. Goar if you want to visit Rheinfels Castle and towns on the west-bank (also called the "Left" side.)

Ferry schedule: click on the "winter Sep. - Mai" box for fall:

https://faehre-loreley.de/fahrplan/#tabs_desc_8773_2

The St. Goar rail station is just a few uphill steps from the KD dock.

The St. Goarshausen train station is simple to reach on foot from the KD dock or the ferry dock. Just walk north along the main drag through town. If you're using the train to return to R'heim, there are hourly departures from St. Goarshausen at :27 after the hour, peppered with a few departures in between those.

One-way fare for two is €11.20 for the 25-min. trip to R'heim. You should find a ticket machine at the station. However, if you will be making other train journeys too (to the west bank towns, Koblenz, Marksburg Castle in Braubach, etc.) then maybe a day pass would be wise (and more convenient.) The Rheinland-Pfalz Ticket (€31/2) would cover everything (including the St. Goar ferry.)

https://www.vrminfo.de/en/tickets/tickets/ticket-offers/rheinland-pfalz-ticket/

This day pass could be bought at R'heim station (or any other station) for the specific date of your outing.

The 9:00 boat from Rüdesheim only stops at St Goarshausen, not at St Goar. The next boat, 11:00 from Rüdesheim, stops at both St Goar (first), then St Goarshausen.

I remember, some years ago, reading an account by some travelers who took a K-D Rhein cruise. They wanted to get off at St Goar, but the boat stopped first at St Goarshausen, so they figured they better get off there. They then watched with chagrin as the K-D boat went across the river to St Goar without them, and they had to buy a ticket for the ferry.

@Lee: You are reading the schedule correctly. However, according to certain trusted Tripadvisor sources with boots on the ground in Germany, the 9:00 boat makes an unscheduled trip to St. Goar immediately after the St. Goarshausen stop, just like the one you reported from several years ago.