I see in the April 2019 issue of Sea Breezes that the writer of ‘Hotelships’ declares that the river vessel has “a unique feature”, ie a bridge that can be raised / lowered to facilitate passage under low bridges.
I enclose a photograph of my 1989 ship, Crescent Shipping’s Vibrence. Before heading up one of Europe’s canals (with very low bridges), we took some time to ensure that everything that should come down, did!
The bridge went right down into its well, even the funnel could be detached, and the accommodation entrance ‘cowl’ could be partially dismantled.
Not that we were a glorified barge; she was a brilliant sea boat, coping with the worst the Bay of Biscay, for example, could throw at us.