Ultrasonic measurement of oil slick thickness using a remotely operated vehicle (ROV) as a platform in various sea wave states

Abstract

To overcome the difficulty of estimating the oil slick thickness using remote sensing techniques, the feasibility of applying the proposed ultrasonic method for measuring the thickness of the oil slick in open water was experimentally investigated by conducting tests in various sea wave states. The second cross-correlation method was implemented to calculate the time of flight (TOF). The influences of sea waves on measurement accuracy were deeply evaluated by calculating the difference of the average thickness in the sea wave state compared with the average thickness in the calm sea state (no waves). The results showed a high measurement accuracy with a maximum difference ∼17.3%, and most of the tests (10 in 15) had a difference within ±10%. The measurement accuracy was further improved by correcting singular thicknesses caused by the ROV's pitch and roll, and surface waves. The study will advance the development and transition of this method to be implemented in open water.