When do you give up on an engine.

[LittleSister]

Nice story. As well as already being the limit case of not owing anyone anything, it can presumably run on non-fossil fuels, so its more future proof and sustainable than anything else around

If I remember correctly (it's some years since I was on it) its boiler is oil fired, but the Museum of the Broads also has an electric launch, reportedly charged by the Museum's solar panels.
Boat Trips - Museum of the Broads

Meanwhile, the Broads Authority has several electric launches, one of which, Ra, which is powers by the solar panels on its roof (though I have heard rumours that it is not entirely problem free on that front).
https://www.broads-authority.gov.uk/boating/hiring-a-boat/boat-trips

 

[ducked]

If I remember correctly (it's some years since I was on it) its boiler is oil fired, but the Museum of the Broads also has an electric launch, reportedly charged by the Museum's solar panels.
Boat Trips - Museum of the Broads

Meanwhile, the Broads Authority has several electric launches, one of which, Ra, which is powers by the solar panels on its roof (though I have heard rumours that it is not entirely problem free on that front).
https://www.broads-authority.gov.uk/boating/hiring-a-boat/boat-trips

View attachment 196831

Could probably do vegetable oil or at least biodiesel, but then so, probably, could a diesel, though perhaps not for so long.

Battery launch you got battery life issues

Directly solar-powered,if thats the case, OK, that might beat it, depending of panel and motor life