The ship is very limited in the number of family cabins available and therefore they must be allocated to crew that can work full-time in a critical operational position on board. When we accept any family unit, we expect one of the parents to work full-time while the other parent’s main responsibility (due in a large part to safety issues) would be to take care/watch after their children when they are not in school. This would not work in the case of the single-parent family, as their time would have to be split between their parental and shipboard duties and therefore not allowing the crew member to work full-time.