Ship Captain: a self-explanatory role.
Hmm, I don't think it is particularly self-explanatory. The description for Seaman says "All ships must be manned by a crew of Seamen under a Ship Captain". Unfortunately nothing is explained about what happens if there is no Ship Captain. I fully understand the spirit of making it up as you go along, but in this case it could have been tied into the Command Control rules on page 32. Perhaps it would affect morale, or in times of trouble (like a storm, a monster encounter, pursuit, or navigation) to not have a Ship Captain.
There has been some discussion on Grognardia about the venerable Sage's Advice column in Dragon magazine. Rereading the LBB I can see how a need for a column like Sage's Advice came to be. It's unfortunate the 'rules lawyer' mindset was so prevalent (I remember it being that way too in middle school), but the LBB's certainly do lead to a great deal of confusion by their generally poor organization and scant explanation. So much is assumed, and I think those assumptions were probably overwhelming even for the hardcore wargaming crowd at the time.
Of course looking back at those books, it is charming that OD&D was so rough, and have just enough description to light the fire of imagination. The ambiguities lend a tremendous amount of mystique, and I have little doubt helped the popularity of these great little books.