127-Day Atlantic Crossing Demonstrates Autonomous USV Endurance

Oshen’s sail-powered C-Star PC13 has become the first autonomous vessel to cross the Atlantic entirely unaided, completing the Microtransat Challenge after 127 days at sea.

The 1.2-meter (4-foot) Uncrewed Surface Vessel (USV), developed by the Plymouth-based maritime technology company, traveled 2,926 nautical miles (5,400 km) from Gran Canaria to a designated finish line east of Barbados without external intervention in its navigation.

PC13 departed Gran Canaria on May 7, 2026, and crossed the finish line at 09:56 UTC on September 13. The crossing marks the first successful completion of the fully autonomous category of the Microtransat Challenge, which had remained unclaimed for 16 years despite more than 30 attempts.

Microtransat Challenge Requirements for Autonomous Vessels

The Microtransat Challenge was established by Dr. Mark Neal of Aberystwyth University and Dr. Yves Briere of the Institut Supérieur de l’Aéronautique et de l’Espace (ISAE) in Toulouse. The competition challenges teams to cross the Atlantic Ocean in the fastest time using small robotic sailing vessels.

Under the rules for fully autonomous entries, vessels must complete the crossing without assistance from their operators. Once underway, teams cannot influence onboard decision-making or alter the vessel’s course, requiring navigation to be managed autonomously throughout the voyage.

Vessels must also measure no more than 2.4 meters (7.8 feet) in length. This restriction limits the deck area available for solar panels and, consequently, the electrical power available to onboard systems, including computers and thrusters.

Although remotely controlled vessels have previously completed Atlantic crossings using instructions transmitted from shore, the fully autonomous category presents different technical requirements.

Since 2010, more than 30 attempts have been made by organizations including Shanghai University, France’s École Navale and the United States Naval Academy, which has attempted the crossing six times.

Oshen achieved the first successful fully autonomous crossing on its third attempt.

Previous Crossings and Long-Duration Vessel Testing

Oshen’s successful voyage followed two earlier Microtransat attempts that contributed to the development of its C-Star technology.

The company’s first attempt, in 2023, ended after 20 days, with the vessel having traveled approximately 10 km.

A second attempt followed in 2025, when a modified vessel departed Plymouth and remained at sea for 277 days. It completed approximately three-quarters of the Atlantic crossing before losing its sail in heavy seas.

Experience from these voyages, alongside a further 1,000 days at sea, contributed to Oshen’s ongoing technology development.

C-Star vessels are now routinely deployed on long-duration missions in extreme marine environments, supporting scientific research, environmental monitoring and maritime security applications.

Autonomous Navigation and Marine Data Collection

Oshen’s C-Star vessels use autonomous navigation software developed by the company to manage their movements at sea.

The software continually assesses wind speed and direction, ocean currents and battery life, allowing vessels to hold position or sail toward preselected destinations.

C-Stars can operate individually or in fleets, referred to as constellations, and function as sensor platforms for collecting oceanographic, climate and wildlife data.

The vessels can record up to two million data points per day, measuring environmental variables including sea surface temperature, air temperature, air pressure, humidity, salinity and water density.

Alongside scientific data collection, C-Stars are used in defense applications to help safeguard undersea data cables and pipelines, monitor illegal fishing activity and track dark fleet tankers. These applications involve extended deployments in offshore environments, where autonomous navigation and sustained environmental data collection form part of vessel operations.

C-Star Deployment During Category 5 Hurricane Humberto

The endurance of Oshen’s C-Star vessels was also demonstrated during a September 2025 mission for the US National Oceanic and Atmospheric Administration (NOAA).

Three C-Stars deployed on the mission intercepted Hurricane Humberto, with C-Star PC8 sailing directly into the storm’s eyewall while the hurricane was classified as Category 5.

PC8 survived several hours in conditions involving waves of approximately 10 meters (30 feet) and winds exceeding 240 km/h (150 mph).

During the encounter, the vessel transmitted live data that was subsequently reported in official weather forecasts. According to Oshen, C-Stars remain the only USVs to have achieved such an encounter with a Category 5 hurricane.

Although PC13 did not encounter a hurricane during its Atlantic crossing, it sailed through the developing low-pressure system associated with Storm Dolly on August 28 and 29, approximately 113 days into the mission.

First Successful Fully Autonomous Microtransat Crossing

PC13’s arrival east of Barbados completed a challenge that had previously resisted attempts by academic institutions, naval organizations and maritime technology teams.

The vessel’s crossing met the Microtransat requirements for fully autonomous operation, with onboard systems managing navigation and decision-making throughout the 127-day voyage.

Anahita Laverack, CEO and co-founder of Oshen, said, “We are thrilled to have finally completed the Microtransat. Even in the final hours, after so many days at sea, we weren’t certain that PC13 would reach the designated finishing zone. It is a great result and a fantastic validation of all the effort the team has put into making C-Stars the world’s most capable sail-powered USV. It also means a great deal personally: it was learning about the Microtransat Challenge, while at university, that set us on the path to creating Oshen.”

For more information, visit the Oshen website.