GIB and Japanese investment bank Marubeni have agreed a £370 million (EUR 464 million) deal with a consortium of lenders to make funds available for investment in new projects.
The consortium's members include the Japan Bank for International Cooperation, the Bank of Tokyo-Mitsubishi UFJ, Mizuho Bank, Siemens Financial Services and Societe Generale Corporate & Investment Banking.
GIB and Marubeni hold a 50% stake in Westermost Rough, with Danish developer Dong Energy owning the remainder.
Dong sold half of the project to GIB and Marubeni in March for £240 million. Marubeni and GIB pledged to commit £500 million to the project's construction.
All foundations at the development, nine kilometres from the coast, were completed in May. Westermost Rough will be the first commercial project to use the Siemens 6MW turbine.