That is a novel use of the word solo. If ships normally traveled in groups then solo would be apt but since they dont usually go around in groups I would not use that word. Derelict, adrift, unmanned, unmoored, even rudderless. With the internet everyone is a writer but there arent any editors.
Good point.
Well, it was without a crew.
But you’re right. Any of those words would have been more descriptive and accurate.