When Julian and I are crewing Josephine, I am most definitely The Captain.
Although many of the responsibilities on board are delegated to my stoker (navigation, signalling and sweeties being some of the most important) I take full responsibility for decisions made whilst awheel. When I issue an instruction, we have a rule that it is to be followed without question and immediate confirmation given. For instance, if I say "signal right", she calls that she's signalling because I want to know that her arm is out - even before I check over my shoulder.
There's a good reason that ship's crews reply "aye-aye" to an order - in the heat of battle, the Captain wants to know that the order has been heard. I see no reason to deviate from this scheme of things aboard a tandem.
Also - and let's face it - if you're rocking the appropriate
pirattitude, Captains are just way cooler than pilots