How plausible is the Jack the Ripper seaman theory?

How plausible is the theory that Jack the Ripper was a seaman or sailor?

Possible, but no more securely established than several other occupational theories, and the evidence does not justify a confident identification.

The suggestion that Jack the Ripper was a seaman is possible rather than proven. It sits alongside theories naming a surgeon, butcher, aristocrat, or other occupation. Some books build compelling cases, but none provides enough evidence for a confident identification. The answer also limits its authority because the subject was read for teaching in London rather than studied as a research specialty.