My idea was to use this boat mainly on inland waterways and with a cruising speed of 7 to 9 knots. For this I think anything between 25 and 75 kW will do, depending on the torque. An electric motor of 25 kW on a shaft is the closest to compare with your air-engine I think? Space is available under the forward sofas at the windscreen.
The boat is pretty narrow for low resistance and has a glass-top that can be pushed forward to open up half of the salon to the sun. A perfect picnic-boat but also possible to sleep a couple for a weekend-trip.
As more lakes and waterways are not allowing boats with petrol or diesel propulsion, the electric motors or your air-engine will become the best options for powerboats.
"A future Classic perhaps..?"
