An interesting short video. Heard about this first from BBC. (Thanks to my wife.)
A drone reaches people in the water and drops an inflatable float. This might be useful as a response to a man-over-board, particularly if the drone were equipped with low light level/IR. The drone could not only drop a float but could also hold position over the person in the water until the ship can come back for a pick-up. A light on the drone might help.
Chuck Hill's CG Blog 
I think this is where we are headed with Drone use. I think Small Drones would be great on small boats such as RB-M’s, RB-S, WPB’s and FRC’s. Small drones can be used for over the horizon SAR, Disaster assessments and and even for ATON and bridge inspections.