Proposed Oceanic III

>>Why should this not have worked on a grander scale?<<

Ultimately it did. However, you need to keep in mind that shipowners tend to be a bit of a conservative lot and they don't try new things lightly. Especially with ships that are large and expensive. If the plan was to stick with turbines and/or reciprocating engines, it was because these were proven systems.

If they were to gamble on something new, it would be understandable that they would want to be certain that it would function reliably.