An investigation is underway after an accident at one of Europe’s largest offshore wind farm projects left five injured – becoming the second major incident to confine an installation vessel to port this month.

The accident involving the Seaway Strashnov vessel took place on 8 May during foundation installation at the 860MW Triton Knoll project off eastern England.

News of the incident has only just emerged, with few further details available.

A statement from lead developer Innogy said: “An investigation is being carried out into the cause of an accident which happened overnight on Friday 8 May, involving five people who were working on the Seaway Strashnov for Triton Knoll Offshore Wind Farm.

"At the time, all five were airlifted to hospital for assessment and treatment. Three were discharged the next day and a fourth a few days later, while one person remains recovering in hospital.

"The Strashnov and its crew have returned to port while the investigation is underway. Our priority remains the safety and wellbeing of all those involved, and to support the investigation team and the implementation of their findings."

The incident is the second this month to confine an offshore installation vessel to port this month.

Earlier in May Recharge reported how the Orion 1 that’s due to work on several big projects was damaged in a crane accident during testing, with several workers injured.

A spokesman for Innogy told Recharge the developer expects the delays caused to foundation installation “can be contained within the overall contingencies allowed for in the project programme”.

Triton Knoll will deploy 90 MHI Vestas off the county of Lincolnshire, with commissioning due in 2021. It will become the latest offshore wind giant in the UK North Sea, which is already home to the 1.2GW Hornsea 1 project that’s the world’s largest in operation.

Innogy owns 41% of the project, with other investors including Japan’s J-Power (25%) and Kansai Electric Power (16%).

The Strashnov had already been involved in installation the wind farm’s two offshore substations.

Seaway Strashnov’s operator, marine contractor Seaway 7, told Recharge in a statement that the remaining crew are safe and returned to port in Rotterdam.

“At the time, we mobilised our emergency response teams who were able to monitor and respond to the situation. Our priority is to ensure the safety and wellbeing of all individuals involved.

“We are working with the relevant authorities and all other involved parties to enable a comprehensive investigation into the cause of the incident. We would like to thank the emergency services for their support throughout the incident,” said the statement.