Speculation leading to a question to answer one of Urza's questions in the thread for the update. (164 for later reference):
Theoretically, Belles know how they work. they know everything about themselves from their top speed to the range of their guns and the amount of shots they can fire continuously before overheating. Perhaps the "Captain of the Fleet" drastically improves a belles potential by being a man who can interact with the crew and has an incentive to keep the ship and all men on it afloat. Naturally belles have been smart enough to figure out naval tactics out on their own, but they aren't necessarily empathetic to the crews on board in a way the skipper would have to be. A belle cannot act on any ambitions she has without a crew loading the guns and working the radios.
So what I'm thinking about is the Morganas' effects/auras. I Imagine captains are chosen in part because of these. Most, if not all, naval crews have shown vulnerability to the Morganas' effects. As stated earlier, a Belle cannot fight without her crew, so this would be somewhat infuriating for a belle without a Captain. But perhaps a Captain of the Fleet is chosen because he does not lock himself in his stateroom or jump ship at the sight of a terror-class battleship. Perhaps he stands tall while the crew all collapses hunting down an Asphyxiation-class submarine, and maintains the level head required to disengage and finish it off another day.
So the question if used for an update is:
To what extent are Captains affected by Morgana auras?