Microtransat Challenge: ‘C-Star PC13’ became the first autonomous robotic boat to cross the Atlantic

​An autonomous sailing boat just 1.2 metres long has become the first vessel ever to overcome the toughest challenge in maritime robotics: the Microtransat Challenge. The “C-Star PC13”, built by the British company Oshen, crossed the Atlantic in 127 days entirely without human intervention. More than 30 teams had previously attempted the feat – and failed.

On 13 September 2026 at 09:56 UTC, the “C-Star PC13” crossed the finish line east of Barbados – but there was no one on board to celebrate. The autonomous vessel had covered 2,926 nautical miles in 127 days. It had set off on 7 May from Gran Canaria. Sailing on the trade winds, the robotic yacht had to navigate busy shipping lanes and weather Tropical Storm “Dolly”. During this time, it independently diagnosed and corrected steering problems. Finally, it reached its destination. The “C-Star PC13” won the Microtransat Challenge. The first autonomous sailing boat since the Challenge first began 16 years ago.

​First success in 16 years

The Microtransat Challenge was launched in 2005 by Dr Mark Neal of Aberystwyth University in Wales and Dr Yves Brière of the Isae-Supaero aerospace institute in Toulouse. However, the first launch did not take place until five years later. The stated aim of the competition is to drive forward the development of autonomous marine vehicles.

A major challenge​

The rules are strict. The boats may be no more than 2.4 metres long – which severely restricts the area available for solar panels, thereby significantly limiting the overall energy balance on board. The most striking rule, however, is that no human intervention of any kind is permitted once the boat has crossed the starting line. This rules out remote control via radio. Wind power is the only permitted means of propulsion.

Numerous attempts

​Since the first attempt in September 2010 – when Aberystwyth University’s “Pinta” took to the water – more than 30 teams have taken part in the Challenge, including Shanghai University, France’s renowned École Navale and the US Naval Academy, whose teams made six attempts alone. All failed. Oshen is the first company to succeed – though only at the third attempt.

​Failed three times – learnt three lessons

The success story of the “C-Star PC13” is also a tale of two failures. In 2023, Oshens’ first attempt ended after barely 20 days – the boat had covered only around five nautical miles. In 2025, the team made significantly more progress. A modified boat set sail from Plymouth, sailed for 277 days and covered three-quarters of the Atlantic crossing – until a severe storm destroyed the sail and brought the project to an end. These setbacks were, as those involved themselves see it, the real development work.

Software to combat wind and electricity

At the heart of the “C-Star PC13” lies sophisticated technology and complex software. Before setting sail, waypoints are programmed into the on-board computer. The autonomous navigation software – developed entirely by Oshen – then continuously calculates the optimal route, taking into account wind direction, wind strength, ocean currents and the current battery level. The sails and rudder are automatically adjusted accordingly.

Robot boat with a bow thruster

Although the boat is fitted with a solar-powered bow thruster for manoeuvring in light winds, the rules of the Microtransat Challenge meant that this could not be activated during the Atlantic crossing. The vessel was therefore entirely reliant on its sails and computer systems.

Independent problem-solving whilst on the move

Halfway through the journey, a serious problem arose. The rudder began to respond erratically, presumably caused by excessive friction. However – and this was perhaps the most impressive detail of the entire journey – the control software recognised the problem, automatically adjusted its corrections and compensated for the fault without any human intervention. As a result, the boat was able to continue its journey undeterred.

Tropical storm ‘Dolly’ and 9-metre waves

The crossing was by no means smooth sailing. On the 113th day, the “C-Star PC13” crossed into the influence zone of the developing tropical storm “Dolly” – with waves of up to nine metres, which are challenging conditions for a 1.2-metre boat. The company had already demonstrated in September 2025 that Oshen could cope with such extreme conditions. Its sister vessel, the “C-Star PC8”, was sent directly into the eye wall of Hurricane Humberto on behalf of the US National Oceanic and Atmospheric Administration (NOAA). The vessel withstood hours of exposure to ten-metre-high waves and wind speeds exceeding 240 km/h, whilst transmitting live measurement data that was later incorporated into official weather forecasts. To this day, the C-Stars remain the only unmanned surface vessels ever to have achieved such a feat.

Floating research platform

For Oshen, the Microtransat Challenge is not an end in itself. The C-Stars are primarily designed as autonomous sensor platforms for continuous operation on the open ocean – in regions where deploying conventional research vessels is too expensive or logistically too complex. Each day, the boats continuously measure up to two million data points: sea surface temperature, air temperature, air pressure, humidity, salinity and water density. Whether operating individually or as part of a fleet – Oshen refers to these as ‘constellations’ – they can build up persistent datasets across vast areas of the ocean.

In addition to climate research, areas of application also include:

• Defence: Monitoring of underwater data cables and pipelines
• Law enforcement: Monitoring illegal fishing and so-called ‘shadow fleet’ tankers
• Meteorology: Hurricane monitoring in the Caribbean (already in operation)
• Future: Hydrophones for monitoring underwater activity

A great success

Anahita Laverack, CEO and co-founder of Oshen, commented on their arrival in Barbados: “We are delighted to have finally completed the Microtransat. Even in the final hours, after so many days at sea, we weren’t sure whether the ‘C-Star PC13’ would actually reach the finish line. It’s a brilliant result and a fantastic vindication of all the hard work the team has put in.”