So, having done a walk around the docks... There are two stations on the way between the Docks and Aschaffenburg Hbf. - Sud and Hochschule. Either a 628 or a 642 would do, or you can have a Voith Gravita with a museumszug off to the harbour. There's a blog of the DMU journey here: http://donauwalzer224.blogspot.com/2012/07/die-db-regionetze-teil-1-westfrankenbahn.html I do like this route, it has a great feel about it.