I was working on the next mission for my happy band of lunatics, and needed a short range ferry to be hijacked. So I went looking, and found the Meteor hydrofoil, a Soviet design from the late 50s that was in productions from 1961 to 1991, with hundreds made and dozens exported. The Meteor is the river version; there's an open ocean version called the Kometa that has a longer range, more powerful engines, and carries fewer passengers, but is very similar overall.
This deck plan is based on a real life configuration used as a passenger ferry, and is more or less accurate.
The blue is the external deck, pink is windows, and the gray decks are either a little higher or a littler lower than the main deck, as marked.
(Click the image for a larger version.)