You always want your gunners to be at least 4 to 6 levels higher than your BO, so that you can use the proper guns for the ships you are in (guns normally run around 2 to 4 levels above the ship that they best fit, except in some extreme circumstances).

Your gunners accuracy and reload ability will increase as their level increases and you are able to class them as higher gunners.

Problem is the BO usually gets more exp than the rest of the crew so it helps to have two BOs on two ship lines.  That way you can switch your gunners between ships to stay ahead of the BOs (plus you get another ship line)

BOs and Gunners have the same exp gain rate, so yes, using another BO will get the gunners above both BOs, but you don't need to bring them up all the way with two BOs (if you don't want to). There is always also the option of leveling the gunners up with a different crew/nation to get them ahead of your BO.

Thanks Guy's this information will really help me out in the long run. I tried asking people in the game but just did not get no help at all. With the help I just got and the information i received. Makes me wanna look forward to more gaming in navyfield. But I think I am going with to go BO class BB and CV. not sure how it will turn out, But I am going to be definately going to the BB class with the gunners I have. all i need to do now is work on my manual aiming.