A new technology using a remotely-operated vehicle (ROV) for hull survey developed byDet Norske Veritas. Resonance thickness measurement sensors are mounted in an array ten wide across the full width (1m) of ROV. This crawls over the hull surface taking mean thickness measurements at the speed of up to 1 m2/sec. The ROV,s movements are controlled by special positioning and navigation systems. The scanner can also be used internally for scanning tanks in ballasted condition.