"Compared with human divers performing the same task, the Rangerbot is cheaper, more efficient and able to operate at all hours of the day and night."
So why does it only operate 8hrs of the total possible hours it could function? Must be a Union or something here.
Probably because of “battery limitations”. Deploy more and give them an underwater wireless/contact pad recharge station and they could get 24/7 coverage.
Maybe the batteries need recharging after 8 hours, but they can use it anytime of day or night.