Rhein Cruise Question

Q1: Just read FAQ on website: https://www.k-d.com/en/faq/

Q2: If nobody answers contact Braubach tourist info or the place you want to embark.

You probably do not want to start a cruise from Lorch. That would omit some of the best river scenery. Anyway, hand luggage is permitted, and it's not uncommon for people to board with bags like the black ones you see in this photo (2 women w/ sm. backpacks plus hand luggage.)

Speaking of scenery... as you already know from the KD schedule, the number of KD boats cruising as far north as Braubach and Koblenz is reduced. BR cruises don't even cover that stretch. This is mainly because the scenery to the north is a bit less impressive (so the demand for cruising is lower.) Also, cruising the whole way to Braubach means a KD "N" fare of €44.40; by comparison €20.80 will get you on a KD boat to St. Goarshausen, after which you take a 20-minute train ride to Braubach (€5) which shows you the remaining river scenery from the train window. The walk from the KD dock in St. G'hausen to the station is short, flat and simple. If you haven't considered this approach to Braubach, you might.

You can store your bags on the ship downstairs, with everyone else's luggage. This is really common.
Your problem may be where to store it once you get to Braubach.

Tell us a little more about this trip. Are you starting the day in Rüdesheim after spending the night there, or are you coming into Rüdesheim that morning from somewhere else? How? By train? Are you ending the days travel in Braubach for a specific accommodation or to see the Marksburg? Or are you going on after arriving in Braubach?

1. The earliest you can arrive in Braubach on a KD boat is after the last tour of the Marksburg, so if touring the Marksburg was the objective, you really need to take an earlier boat to St. Goarshausen and train from there.
2. If you are starting the day somewhere other than Rüdesheim, you can train to Rüdesheim and get a 20% discount on you boat ticket by showing your train ticket.

Thank you all so much for your input. To answer some of your questions...

The day prior, I'll be taking the train from Salzburg to Rüdesheim and spending the night there. The next morning, I was planning to stroll around town, maybe go up to Niederwalddenkmal and/or over to Burg Ehrenfels so I could enjoy walking through the vineyards, grab a Rüdesheimer Kaffee, then taking the 11.15 to maybe St. Goar or Oberwesel, until the next boat arrives to continue up to Braubach, where I will be staying that night and visiting Marksburg the next morning before pressing on to Köln (via train). I may also wait for the 14.15 and just go straight to Braubach.

The only parts to this for which I have obligation are my hotel in Rüdesheim and my Pension in Braubach. I've read other threads to try to determine which parts of the Rhein I would most like to see, and I'm sure I will be "over-covering" but I have a day and will be a nice change of pace from the train. And I realize getting off the boat would require me to drag my bag with me. My largest concern was being able to take my bag on the boat to begin with, which seems not to be an issue.

So as always, I will gladly take suggestions from you all about this.

"...then taking the 11.15 to maybe St. Goar or Oberwesel, until the next boat arrives to continue up to Braubach..."

St. Goar's Tourist Information office will hold your bags while you visit Rheinfels Castle or whatever. See their open hours and contact info here. I am unsure whether Oberwesel does the same - On a Friday in September it's open 9:00 - 13:00 and 14:00 - 18:00:
info@oberwesel.de

If you could indicate WHICH Friday in September, there's a reasonable chance you could get in on a wine festival in one of the towns. There's usually one somewhere in the area every weekend.