"Fossil-fuel powered USVs don't have great persistence and are noisy; and some other countries run USVs on renewable energy," CEO and founder Rob Dane said. "But the Bluebottle uniquely uses three forms of renewable energy under seven patents in multiple countries."

The event was attended by Rear Admiral Pete Quinn, who christened Bluey.

"It's a pleasure to be here as the Navy sponsor for this magnificent capability," RADM Quinn said. "Five of these vessels will work as a collaborative team to help inform us as to how we can employ this technology.

"We don't have the mass to allow persistent surveillance of our immediate strategic area of interest. This is what we need to do that in a more complex security environment."