Look man, when I was in the Fleet I was in a serious relationship myself. What type of woman does it take? Its obvious stuff, and not all that romantic: She HAS to be very mature, fully aware of what she's getting herself into (The stories I could tell...don't be like my shipmates--be Honest!), has inner strength, a strong moral base (If you don't know what I mean--you'll find out), very much in love, and committed to making the relationship work.
I was fortunate I was with my girl for years before I joined the Navy as we had plenty of time to build our relationship. No woman will have every quality listed (and there are plenty more), but should come damn close. Don't worry so much about finding her, just enjoy your youth and she'll find you. And believe me, you'll know.