Maintenance access can enlarge uncrewed vessels

A large uncrewed vessel may still need internal room for people to reach equipment during maintenance. Predator, Reaper, and Global Hawk aircraft provide the comparison, with their systems accessible from outside the fuselage. In this explicitly speculative argument, maintenance space increases hull or pressure-hull size, requiring more propulsion power and larger ballast tanks. Removing the operating crew therefore need not remove all the space and cost associated with maintaining the platform.