Confused about navy BAH, do you get it while at sea/deployed?

I am goign to be joining the navy, I was told taht i'll be eligable for approx. 800 BAH. I found some great apartments, but someone told me that I won't be able to get BAH when deployed if I have no dependents? is that true? will I have to pay out of pocket when away to keep the place? It's in Norfolk Virginia, is it easy to find a sublet if that is the case or no.