The Heart of Blackbeard by Patricia Cooper Baker

Why would a teenage girl marry Blackbeard, a fearsome pirate twice her age? Marybeth and Bath Towne have survived a string of disasters, and pirates aren't the worst of them. Mary and her mother see Blackbeard as a chance for survival, and Governor Eden thinks Edward Thache might be good for Bath. Maybe they're right. But could it possibly be a happy marriage for Marybeth? When time traveler, Aurora Saunters, lands in Bath by accident, that's bad luck for her. But maybe she and her grandsons can improve the young bride's chances for a happy future.