Anchor Scope Calculator
Compute rode length, swinging radius, and storm-anchoring recommendations for your specific conditions.
Depth at low tide (the worst-case depth).
How much will the tide rise while anchored? Use 0 for non-tidal waters.
Measure from waterline to where the rode exits the roller.
Normal: <15 kt wind. Rough: 15-30 kt. Storm: >30 kt.
Required Rode Length
189ft
7:1 scope · effective depth 27 ft
Swinging Radius
187ft
The boat will swing in a circle of this radius around the anchor. Verify clearance from other boats and shore.
Recommendation
Normal anchoring — deploy 189 ft of rode. Back down at idle for 30 seconds, then verify set with landmark bearings.
How this works
Anchor scope is the ratio of rode length to effective water depth (depth + tide rise + bow height). The standard ratios are 7:1 for normal conditions, 10:1 for rough weather, and 15:1 for storm anchoring. All-chain rodes can use 2:1 less scope because the chain’s weight creates a catenary curve that absorbs shock loads.
The swinging radius is the horizontal distance the boat will swing around the anchor — calculated via the Pythagorean theorem. Use it to verify you have clearance from other boats, shore, and underwater obstructions.