Abyss Lantern Eye S

Limitation of Manual Inspections of Mooring Chain

Mooring chains are a critical part of onshore and offshore assets. They are typically inspected for wear by extracting the multikilometer chain from the water and laying it out on land. This process is logistically complex, highly disruptive and resource intensive.

Abyss Lantern Eye S: In-service Assessment of Mooring Chains

Abyss Solutions has developed and tested its Abyss Lantern Eye S service, a state of the art, inspection approach and hardware system for sub millimeter accuracy measurements of oscillating mooring chains underwater. This approach will avoid the limitations of manual inspections by conducting in situ inspections with ROVs and stereo photogrammetry.
The Abyss Lantern Eye S comprises of a unique imaging hardware, that has the capability to capture precise high definition images in challenging underwater environments. The hardware can be easily integrated with a wide range of underwater platforms, making the easily deployable with current subsea operations. The hardware, is extremely compact and can be deployed on very small ROVs, in the 30kg class.
The data output is coupled with precision analytics to deliver comprehensive and accurate structural reviews of the assets. These include mm precision measurements, interactive 3D models and automated fault analytics.

Result Methodology

First Stage: High-fidelity Imagery of Mooring Chains

• Mooring chain images captured present accurate color representation, high clarity of fine details and with no observable blur.

• Hundreds of stereo image pairs are captured of the accessible surfaces of the chain in a single inspection run

• During the inspection process, minimal adjustment including strobe positioning for the ROV platform setup and camera exposure time is required to minimize motion blur

Second Stage: 3D Visualisation and Measurements of Mooring Chains

• 3D models of the oscillating mooring chain can be generated within 5 minutes from which measurements can be drawn.

• Comprehensive and accurate reconstruction and reporting can be completed within 8 hours

• Using the 3D models, highly accurate measurements (as compared to measurements taken manually by vernier calipers) can be obtained which includes the bar diameter, grip length, stud length and pitting.

Key features of the Abyss Lantern Eye S Service

• The imaging system can be readily integrated on a wide range of underwater remotely operated vehicles (ROV)

• Data collection process is rapid and thorough.

• Rapid turnaround of preliminary onsite measurements to facilitate realtime asset management decision making on the field.

• Comprehensive data processing can be done within hours with higher degree of accuracy. For example, test results of mooring chains have shown that after offsite data processing was conducted within 8 hours, key measurements which were within 0.1mm of the range of caliper readings.

• The service enables asset owners to track change over time

• Material degradation can be estimated and tracked

Sample Measurements

3d Model and Measurements
Bar Diameter
Test results have shown that visual measurements were 0.1mm of the range of caliper readings

Grip Length
Test results have shown that visual measurements were with the range of caliper readings

Stud Length
Test results have shown that visual measurements were with the range of caliper readings
Pitting Measurements
In the left image, measurements taken from point-cloud data with an accuracy of 0.5mm (2-sigma). In the right, a cross-sectional view of the pitting.