Anchor Scope Calculator
Enter water depth, your freeboard, and desired scope ratio to calculate exactly how much anchor rode to let out.
Anchoring Parameters
Distance from the water surface to the seabed
Height from waterline to bow cleat / anchor roller
5:1 minimum; 7:1 recommended; 10:1+ in heavy weather
Calculated Rode Length
—
ft of rode
Depth
—
ft
Freeboard
—
ft
Scope
—
:1
Scope Comparison
| Scope | Rode Needed | Conditions |
|---|
Swing Radius Estimate
—
ft radius
Approximate circle your vessel can swing through once anchored (rode length + vessel length). Keep this clear of other boats and hazards.
Diagram
Summary
Enter water depth, your freeboard, and desired scope ratio to calculate exactly how much anchor rode to let out.
How it works
- Enter the water depth at your anchoring spot (from the surface to the seabed).
- Enter your vessel freeboard — the height from the waterline to the bow cleat or anchor roller.
- Select or type a scope ratio (5:1 is a minimum; 7:1 or more in wind or swell).
- Choose your unit system (feet or meters).
- The calculator instantly shows the required rode length and a visual diagram of the setup.
Use cases
- Determine how much anchor chain and rope to deploy before dropping the hook.
- Check if you have enough rode aboard for a particular anchorage depth.
- Compare required rode lengths for different scope ratios in changing weather.
- Teach new crew members the relationship between depth, freeboard, and scope.
- Plan overnight anchorages with appropriate swing radius estimates.
- Verify safe anchoring depth limits given the rode length you carry.
Frequently Asked Questions
Last updated: 2026-06-11 ·
Reviewed by Nham Vu