Officers received a report around 9.20pm that Jason Thomas, from Wales, was missing from the rig that was being towed.
During their searches, officers communicated with a number of partner agencies, including the rig’s operator and the Maritime and Coastguard Agency.
On Sunday, January 29, officers were able to board the rig and conduct investigations.
They are working with partners such as the Health and Safety Executive and the rig operator to gather any information that may help them determine what happened before Mr Thomas went missing.