Three specialist geotechnical vehicles will collect soil and rock samples from the locations of every one of the proposed 75 turbines. A separate vessel will also undertake geophysical magnetometer and multi-beam surveys.
Mainstream is yet to make a final investment decision in relation to the project, but said that this latest move marks the transition into the final design phase before a decision will be made.
The project is located 15 kilometres off the east coast of Scotland in the outer Firth of Forth. Onshore construction consent has been granted, with offshore permitting due to complete by the end of the year.
If it gets the go ahead, the project will be made up of 75 Siemens 6MW turbines, and is due to come online in 2017.