How to use it
- Depth — the water depth under you now (from your sounder or the chart).
- Rise of tide — how much more the tide will rise before your next low, so your scope holds at high water.
- Bow height — from the waterline up to your bow roller, typically 1–2 m.
- Conditions — pick Settled, Moderate or Heavy to set a sensible ratio, or drag the ratio slider yourself.
The result is the total rode to deploy. Read our full method, with a worked table by depth, in the anchor scope guide, and see how the swing figure becomes an alarm setting in what radius should you set?
Frequently asked questions
Multiply your chosen scope ratio by the total vertical distance from the seabed to your bow roller. That distance is the water depth plus the expected rise of tide plus the height of your bow above the water. For example, at 5:1 in a total depth of 8 metres you let out 40 metres of rode.
A common guideline is about 5:1 for all-chain rode and 7:1 for rope in settled conditions, increasing to 7:1 chain or 10:1 rope in heavy weather. More scope lowers the angle of pull so the anchor holds better, at the cost of a larger swinging circle.
Yes. Enter the expected rise of tide and it is added to the depth so your scope stays adequate at high water, when the boat lies back furthest. Always calculate for the highest water you will see before you next reset the anchor.