Patent ID: 7088640

Claim:
A method of obtaining measurement of the relative position and orientation between at least two subsea structures, the method comprising: fitting a first multi-transducer master acoustic station in known position and orientation relative to a first one of said structures; fitting a first slave acoustic station in known position and orientation relative to the second one of said structures; operating said first master and slave acoustic stations to determine the position and direction of said first slave station with respect to the first master station; fitting a second multi-transducer master acoustic station in known position and orientation relative to the second of said structures; fitting a second slave acoustic station in known position and orientation relative to the first one of said structures; operating said second master and slave acoustic stations to determine the position and direction of said second slave station with respect to the second master station; and combining position and direction data from said operations of said first and second master acoustic stations to calculate relative position and orientation between said structures.