The Mayflower Autonomous Ship (MAS), which had to abandon its transatlantic crossing in June due to a mechanical fault, will be back in the water within the next few weeks after the problem is fixed.

The vessel had to return to Plymouth three days into its voyage, which was originally planned to celebrate the 400-year anniversary of the original Mayflower crossing of the Atlantic a year earlier but was delayed by Covid-19.

The fault, which led to a loss of full-power and speed was caused by a fracture in the flexible metal coupling between the ship’s generator and exhaust system, has now been found.

The MAS has a hybrid propulsion system mainly drawing energy from solar panels, but an on-board generator automatically switches on to top up the battery when required.

Before the breakdown, the vessel had cruised at an average speed of 7 knots over 450 nautical miles.

Apart from the failure, it performed well and demonstrated its ability to handle ocean conditions, said builder non-profit marine research organisation Promare and IBM, which supplied the vessel’s electronic systems.

After the Promare support team determined the issue with the ship’s generator was not possible to repair without human intervention, the vessel was commanded to turn round and return.

The MAS travelled back under its own steam for 30 hours at a reduced speed of around 3 knots, but was then put into loiter mode to conserve power for its communication and video systems until a support vessel could arrive.

The generator has been removed and a replacement ordered and ProMare is performing a redesign of the coupling. It is also taking the opportunity to upgrade some of the edge computing devices to increase the on-board processing power.

Once back in the water in the next few weeks, ProMare said it will make a decision about the ship’s next missions and the timing of the next Atlantic crossing attempt following tests and long-range trials.

“Despite the setback, we’ve learnt a lot and we’re more encouraged than ever that the Mayflower will safely navigate the world’s oceans in the near future,” said Brett Phaneuf, director of the Mayflower Autonomous Ship Project.