Following on from a number of leads, I've been doing some research into the Flettner Rotor. I've summarised the findings in the attached PDF - there's an extensive reference list at the back.
This technology was proven in the 1920s but, as with the electric car and the electric tram, appears to have been consigned to the "too weird and whacky" bin.
Now a wide range of researchers are looking again at the Flettner Rotor as an alternative to fossil fuel powered propulsion for shipping.
There appears strong potential for its use here in Oceania.
All feedback and comments appreciated