Opt Chain Measurement

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Ashtead Technology’s Optical Chain Measurement System (CMS) is a ROV-deployed optical caliper imaging device, which measures mooring chain dimensions and the material condition of links. The tool is positioned on a link to capture video data, yielding real-time measurement results. This data is processed to produce measurements of intergrip, sidebar diameters and link length.

Measurement of chain dimensions is critical to confirm that chain corrosion and wear rates are within expected tolerances and that chains maintain their minimum strength requirements throughout their lifetime. The optical CMS can collect intergrip length, sidebar diameters and link length measurements all in a single ROV dive.

With over 25-years of commercial use and continuous improvement, the CMS is the most reliable, repeatable and efficient method of monitoring mooring chain integrity.

Chain surface preparation should be carried out prior to CMS deployment to remove bulky marine growth from links and all growth from apices. Ashtead Technology’s Subsea Cleaning Tool (SCT) is recommended for highest efficiency.

For more information please read our Mooring Chain Measurement FAQ


Key Features

  • Optical chain measurement in water without operational interruption
  • Accuracy of optical CMS measurements up to +/- 0.5mm
  • Applicable to FPSO, FSO, SPAR, CALM Buoy, Semi-sub and other floating vessels
  • Measurements compared to API standards, class societies and regulatory guidelines
  • Delivery of precise, actionable data and a highly-detailed visual record of measurement locations
  • Optional: Inclination sensor to measure line angles

Accuracy up to +/- 0.5mm

Used for 84-184mm diameter chain, without customization

Results meet Class, API, and regulatory requirements

Faster and improved precision over mechanical measurement

Faster data collection than 3D scanning tools, with results available in-situ

Optional: Inclination sensor to measure line angles



  • In-situ chain measurement
  • UWILD chain inspection
  • Class survey chain inspection