These 23ft (7m), 33ft (10m), or 65ft (20m) long vessels are propelled by wing sails and power their radio and telemetry systems with a combination of solar and battery power.

Hurricane Florence in 2018 is a prime example of this in action. As the storm ripped towards the Eastern seaboard, a convoy of 30 ships left navy ports and headed out to sea in what is known as a ...