Kristian Siem-backed oil and gas contractor and shipowner Subsea 7 is beefing up its renewables operations by buying Arne Blystad's wind farm and heavylift vessel company OHT.

The deal will see a merger of the renewables division of Subsea 7 and OHT, which has a market capitalisation of $239m.

The new operation will be called Seaway 7 and will retain OHT's listing on Oslo's Euronext Growth board, with a view to a future main board move.