Operational Guide · Registers & Logbooks

# Anchor and Chain Cable Survey

Every anchor chain is ranged and measured link by link: an 11% diameter wear on a single length is enough to require its full renewal.

anchor chain cable anchor chain special survey

## Operational Explanation

The anchor chain cable is subject to special survey at five-year intervals, coinciding with the Renewal Survey: the entire chain is ranged on deck or on the quay for visual inspection and gauging (diameter measurement at wear points) of each length.

The permissible wear limit under Class rules is typically a maximum reduction of 12% of the link's nominal diameter: when links within a given chain length are found worn beyond this threshold, the entire affected length must be renewed, not just individual out-of-tolerance links. At the Renewal Survey for ships over 5 years of age, the chain must be gauged and renewed where the average diameter falls below the permissible limits.

The IACS Unified Requirements W2 (specifications on chains and anchoring equipment), updated between 2023 and 2025 to reflect advances in metallurgical control methods and the greater loads required by larger modern ships, have tightened breaking load test thresholds by around 8% and introduced more rigorous non-destructive examination protocols.

## Regulatory Reference

Rules of the applicable Classification Society for the five-year survey (Special/Renewal Survey) of the anchor chain; IACS Unified Requirements W2 (specifications on chains and anchoring equipment), updated 2023-2025 with more stringent breaking load test thresholds and reinforced non-destructive examination protocols.

## Scope of Application

Every ship fitted with anchors and chains, with an obligation for complete ranging and gauging of the chain at the five-year Renewal Survey.

## Procedure / How to Complete It

1. Range the entire anchor chain on deck or on the quay for a complete visual inspection.
2. Gauge the diameter of links at wear points, comparing it with the nominal diameter and the maximum permissible reduction (typically 12%).
3. Visually inspect every link for cracks, distortion, corrosion pitting, and the condition of joining shackles.
4. Subject a sample of links to a breaking load test according to updated IACS UR W2 thresholds.
5. Renew the entire affected chain length when links within that length are found worn beyond the permissible threshold, not individual links in isolation.

## Practical Example

Example of survey: an anchor's chain is fully ranged and measured; a 20-metre length shows an average diameter reduction of 11%, just below the 12% critical threshold, while an adjacent length exceeds the threshold and is fully renewed according to the prescribed procedure, not just the individual most worn links.

## Real Cases

The update to IACS UR W2 between 2023 and 2025, with breaking load test thresholds tightened by around 8% and more rigorous non-destructive examination protocols, reflects the need to adapt anchoring equipment safety standards to the size and loads of modern ships, significantly greater than when the previous specifications were established.

## Common Mistakes Mistake Library

Mistake | Consequence | How to avoid it
--- | --- | ---
Diameter measurement limited to a few sample points instead of the entire chain length | Lengths worn beyond the threshold not detected | Systematically measure the entire ranged chain, not just a sample of links
Renewal of only the visibly most worn links instead of the entire affected length | Non-compliance with the length-based renewal rule, with sub-standard chain parts remaining in use | Renew the entire chain length when links within that length exceed the wear threshold, not individual links in isolation
Breaking load test carried out according to thresholds not updated to the latest IACS UR W2 | Verification not aligned with current safety standards | Verify that the laboratory or Classification Society applies the most recent IACS UR W2 thresholds

## PSC Observations

PSCOs may verify the documentation of the last five-year anchor chain survey and the general condition of anchoring equipment, especially in case of doubts about the ship's general maintenance.

## Operational Tips

- Systematically measure the entire ranged chain during the five-year survey, not a limited sample of links.
- Always renew the entire affected chain length when it exceeds the wear threshold, not just the individual most visibly damaged links.
- Verify that breaking load tests follow the most recent IACS UR W2 thresholds, updated between 2023 and 2025.

## Checklist

- Entire chain ranged for complete visual inspection
- Link diameter systematically gauged at wear points
- Links inspected for cracks, distortion, corrosion pitting and joint condition
- Breaking load test carried out on a sample according to updated IACS UR W2 thresholds
- Chain lengths beyond the wear threshold fully renewed

## FAQ

What is the permissible wear limit for anchor chain links?
Typically a maximum reduction of 12% of the link's nominal diameter under applicable Class rules; beyond this threshold, the entire affected chain length must be renewed.
How often is the anchor chain subject to a complete survey?
At five-year intervals, coinciding with the Renewal Survey/Special Survey, when the entire chain is ranged and measured link by link.
What changes with the IACS UR W2 updated between 2023 and 2025?
Breaking load test thresholds tightened by around 8% and more rigorous non-destructive examination protocols, to adapt standards to the greater loads required by larger modern ships.
🎬 Additional photos, videos and interactive diagrams for this topic will be available in a future version of the platform.

## Related Topics

Dry Dock Entry Planning Survey in Dry Dock

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