Anchor scope
The ratio of anchor chain length paid out to water depth — typically 5:1 to 8:1 for safe holding.
Regulatory detail & full definition
Anchor scope is the ratio of chain length paid out to the water depth measured at the hawse pipe. Common working values: 5:1 in sheltered water, 6-8:1 in exposed anchorage, up to 10:1 in heavy weather. Longer scope reduces the vertical component of the pull on the anchor + increases holding power dramatically. Master computes scope allowing for tidal range + expected weather. See /glossary/scope-of-cable for the traditional per-shackle detail.
Authoritative source: Nautical Institute ↗
Related
Source: Nautical Institute Anchoring Guidance
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