"Left" vs "the left" is not good enough. That could still mean either concept semantically, and you can't be sure the person speaking to you didn't mess up the convention when the two are that close.

A crew (any kind of crew) requires exceedingly clear communication. "Ship left" and "ship right" could work, but what if the environment is noisy and you're not sure if the first word was "ship" or something else? Domain-specific, unique terms are fantastic tools for crews.