I proposed this idea around the time the last pirate attacks were in the news. Merchant ships could provide some sort of landing pad and automatically detaching power umbilical. Such drones could "visit" transiting merchant vessels and land there to loiter in good weather. Once the merchant is out of danger, the drone could fly to its next assignment.

My original idea involved launchers in standard cargo containers, linking to a remote control facility on demand by satellite, but independent drones only requiring such landing pads would be even cheaper.