Abstract
Offshore mooring chains are critical infrastructure for oil platforms, wind farms, and aquaculture installations, yet their inspection and maintenance remain labour-intensive, imprecise, and costly. This paper presents a novel robotic platform designed to do lifetime assessment of mooring chains through autonomous cleaning and inspection at depths down to 500 meters. The robot integrates a chain-crawling robot platform with a non-destructive high-flow cleaning module, and a robust 3D vision system capable of sub-millimetre measurements in dark, turbid underwater environments. By combining mechanical design optimized for complex chain geometries with advanced laser triangulation and parametric modelling, the system enables accurate, repeatable measurements of key degradation indicators such as double diameter and surface roughness/pitting. Experimental results demonstrate high precision in double diameter estimation, surface corrosion metrics and effective cleaning without strain hardening, which in total supports quantitative lifetime prediction models. This robotic system is a significant step toward scalable, condition-based maintenance of offshore moorings, with potential application across multiple marine industries.