I sailed on the dawn in February and I have to say, despite a sign reading "After 5:30, no tank-tops, jeans, ect." people wore what ever they wanted to. Even on the "formal" night, people were allowed to enter in jeans and tank tops. And the formal night isn't required. I think your husband would be fine in nice slacks and a shirt each night . . and a long skirt with a nice top will certainly be fine for you . .