Hi Cliff,
Isn't the ex'WaipaDelta" a cat hull with twin diesel driven jet drive with free-wheeling skinny paddles.
The simple answer to your question is YES there are such drives available out there, but the more usual would be an ic (petrol/diesel) engine driving the hydraulic pump, and the hydraulic motor unit mounted on the paddle wheel hub. Somewhat similar to the stern wheeler on Lake Rotorua and the ones on Sydney harbour and at Brisbane. I'm in Hamilton if you want to pm or email me for any further help or suggestions.
Size of units will depend on what you have in mind
regards
kiwi