Charli McDonald of Gloucester knew she was going to have the life of a nomad when she married John. He had already been in the U.S. Navy for three years, and he was a career man.

Knowing what you’re in for doesn’t necessarily make it any easier. Each time the family moves to a new place, “you don’t know anyone and you have to rely on yourself,” Charli said. “It’s very difficult.”

Navy people move a lot. During the 13 years they’ve been married, the McDonalds have moved six times. They lived in Maine, then Connecticut, then Charleston, South Carolina. Then they were moved back to Connecticut, and back to Charleston once again. At the end of June, when John was transferred to the Norfolk Naval Base, the family moved to Gloucester.

But John will only be home until the end of August before he has to report for duty as the machinery division chief on a submarine being overhauled at the Portsmouth Naval Shipyard in New Hampshire. He ex...