The IEA Wind Task 30 OC4 (Offshore Code Comparison Collaboration Continuation) project was a continuation of the OC3 project of IEA Wind Task 23 Subtask 2, and was initiated due to the strong interest in continuing the work of OC3. The purpose of the project was to perform a benchmarking exercise of offshore wind turbine dynamics codes. OC4 consisted of two phases that were not considered in OC...