The Romanian boats are impressive, but their length limits them to broad waterways.
Well, maybe something more Victorian/Edwardian with a steam-punkish vibe, paddle-steamers with tesla cannon,
or on a straighter more RW theme, modern paddle-wheelers with diesel-electric drive, or turbine electric, paddle-housings
armoured like a few of the USN Civil War period boats.
Choctaw
Lexington
Heck, go Mad Max on the waterways in a post-apocalyptic scenario.