Patent ID: 8820261

Claim:
A method for detecting anomalies ( 16 ) on an underwater object, said method comprising: (i) moving an unmanned underwater vehicle ( 17 ), while the unmanned underwater vehicle ( 17 ) is submerged at a constant depth (T nom ), along the underwater object, the unmanned underwater vehicle ( 17 ) having a navigation apparatus ( 19 ) and an acoustic sensor, wherein the acoustic sensor measures the lateral distance (d) between unmanned underwater vehicle ( 17 ) and the underwater object as the unmanned underwater vehicle ( 17 ) moves along the underwater object, and the navigation apparatus ( 19 ) controls the unmanned underwater vehicle ( 17 ) such that the unmanned underwater vehicle ( 17 ) maintains a constant predetermined lateral distance (d nom ) from the underwater object, (ii) comparing the measured lateral distance (d) as the unmanned underwater vehicle ( 17 ) moves along the underwater object with the predetermined lateral distance (d nom ), and (iii) identifying an anomaly ( 16 ) on the underwater object based on a discrepancy between the measured lateral distance (d) and the predetermined lateral distance (d nom ), wherein the underwater object comprises a hull ( 15 ) of a watercraft.