The AA stat is currently disabled for sailors. Like richard said, you want Reload and accuracy.
My own guide to classing AA gunners (which actually focuses on the benefits of late classing them, but works as a general guide all the same) can be found stickied here. Or;
http://fm.en.kupaisky.com/Community/Forum/View.aspx?page=1&num=13276&category=A03&searchType=0&searchValue=&pageCount=0&sort=5&page1=1