VESSEL REVIEW | SD-3000 – US Navy to deploy wind- and solar-powered USV for ocean mapping missions

The US Navy recently began deployment of a new large unmanned surface vehicle (USV) designed by California-based maritime robotics company Saildrone and built by Austal USA.

The USV, given the official designation SD-3000, was designed for ocean mapping and maritime domain awareness missions. The craft is contracted to the US Navy for initial testing and evaluation in multiple environments. Missions will focus on the ability of the craft to deliver both surface and undersea intelligence for a range of high-priority applications, including anti-submarine warfare (ASW).

The aluminium craft was built to the American Bureau of Shipping (ABS) Light Warship code.

Endurance for months-long operations

The USV is powered by wind energy, solar energy, and a diesel generator for long-range, long-endurance missions in the open ocean. Advanced machine learning (ML) works in conjunction with onboard sensors to ensure comprehensive situational awareness.

Saildrone's proprietary ML model, which can automatically recognise and classify objects in real time, was trained on Saildrone's unique data suite of labeled maritime images, containing millions of images captured during missions over the past seven years. Saildrone's masthead 360-degree optical camera system combined with the ML model can deliver real-time, visual detection of targets at sea, including "dark" vessels that may not be transmitting their position.

"The USV is from a series we developed to have a very low carbon footprint due to their being wind- and solar-powered," Saildrone told Baird Maritime. "We have sailed our three classes of USV from the high north, mapping areas along the north coast of Alaska, to the Southern Ocean where we circumnavigated Antarctica, and everywhere in between."

The USV delivered to the US Navy belongs to a new series that measures 65 feet (20 metres) long, displaces approximately 15 tons (14 tonnes), and is able to carry a wide array of sensors for maritime domain awareness. The sensors allow mapping down to a depth of  feet (11 kilometres).

The USV can operate unsupported for months at a time, during which it can conduct data collection in remote locations worldwide where the deployment of crewed vessels would be impractical. The craft can be transported to where it needs to operate, or it can sail to any work site on its own, thanks to its reliance on wind and solar power.

"It is a challenge to design an unmanned platform that can handle the harsh and unforgiving environment of the ocean and sustain operations in that environment for months at a time," added Saildrone. "We have been iterating on the platform for over 10 years and now have three classes of USV in our portfolio. Every change we have implemented results from learning from our past experiences."

Sensor payload flexibility in a compact hull

Saildrone said the craft was designed to carry many different payloads as required by operators, and it has a significantly higher height of eye compared to the company's smaller vehicles. In addition to high-capability ocean mapping equipment, payload options can also include high-powered radars, a point-tilt-zoom camera, AIS, multibeam echosounders, metocean sensors, and towed acoustic arrays for monitoring undersea activity, thus allowing operators to fill any gaps in ocean data.

"The USV is primarily wind and solar-powered but also has an auxiliary propulsion system and diesel generator it can use when required," Saildrone told Baird Maritime. "Using wind and solar as primary propulsion, the USV can sustain operations for three months or more."

The designer added that, since the USV is larger and taller than earlier craft in the company's product portfolio, the detection ranges of the onboard sensors can be considerably greater.

"We will be working over the next several months to integrate the Thales Blue Sentry thin-line towed array for autonomous ASW."

Austal is currently producing one USV from the same series every six weeks, with the ability to scale up production as demand requires.