Module 3 - Anchorwork
Choosing an Anchorage
What you will learn
Choose an anchoring position that remains viable through the expected wind, stream and water-level changes, with sufficient depth, approach, escape, holding potential and swinging room.
An attractive patch of water is not yet a safe anchorage. Build the choice from current chart and local information, the forecast and tide, the vessel's depth and cable needs, likely holding, restrictions, other craft and a clear way out.
Start with the whole stay, not only the arrival. Check the chart and current local information for depths, obstructions, cables, pipelines, fairways, prohibited or restricted areas and environmental protections. Compare the forecast wind and sea with the shelter available now and later, and identify what would make the anchorage untenable. An anchorage symbol identifies charted information; it does not guarantee room, depth, holding or permission for this vessel today.
Depth and space must work together. Allow for the lowest expected water level and a prudent under-keel margin, then calculate scope from the greatest expected vertical distance between the bow roller and the seabed. The yacht may sweep an area approaching the paid cable plus its own length, while neighbouring craft on different cable or moorings may swing differently. Check the full circle against shore, shoals, moorings, traffic and an escape route.
Seabed labels indicate possibilities, not guaranteed holding. Bare sand or suitable mud can be promising for many yacht anchors, while weed may prevent penetration and rock may foul or give unpredictable purchase, but performance still depends on the exact anchor, size, setting, rode and conditions. Avoid sensitive habitat where possible, use designated low-impact moorings where required, and target verified bare ground rather than assuming every pale patch is safe sand.
| Decision | Evidence to check | Reason to reject or change plan |
|---|---|---|
| Shelter | Forecast wind, sea, swell and local topography through the stay | A later direction exposes the berth or creates a lee shore |
| Depth | Charted depth, tide, draught, bow height and under-keel margin | Lowest-water clearance or maximum-depth scope is inadequate |
| Swing | Paid cable, vessel length, neighbours, shore, shoals and traffic | The swept area crosses a hazard, fairway or another vessel's space |
| Holding and permission | Seabed evidence, anchor system, local rules and habitat mapping | Uncertain bottom, protected habitat, charted cable or local restriction |
Reject a comfortable-looking but fragile plan
A small cove is sheltered from the present westerly wind and has a sandy patch. The forecast backs southerly overnight, low water will reduce depth by 1.8 m, and the paid cable would let the yacht swing across the entrance channel.
1. Project the whole stay
Reassess shelter, wave exposure, depth and traffic for the forecast southerly wind and the lowest expected water level, not the arrival snapshot.
2. Draw the swept area
Allow for paid cable, vessel length and different swing behaviour before deciding whether the channel, shore and neighbouring craft remain clear.
3. Check the bottom and restrictions
Confirm that the intended drop is permitted bare ground and that no cable, pipeline, fairway or protected habitat conflicts with the plan.
4. Keep an exit
If any limiting condition is close, choose the safer alternative before dark rather than relying on a late recovery from a lee shore.
Sense check: A position can be sheltered and deep enough at arrival yet become unsafe after a wind shift, tidal fall or change in traffic.
Common mistake or limitation
- Treating a charted anchorage symbol or a busy cluster of anchored boats as proof that the position is safe and permitted for this yacht.
- Checking only the arrival heading and forgetting the full swing after a wind or tidal-stream reversal.
- Calculating depth from the transducer reading alone without relating charted depth, tide, draught, transducer offset and under-keel margin.
- Calling sand or mud universally good holding without verifying the patch, the exact anchor system and whether the anchor has actually set.
Recap
- Assess the whole stay: forecast, tide, depth, bottom, restrictions, traffic and escape options.
- Allow for the full swinging area and for neighbouring craft to behave differently.
- A promising bottom and an anchorage symbol are inputs, not guarantees that the anchor will hold or that the position is suitable.
Optional quick check
Section 1 of 5
Which finding most clearly invalidates an otherwise sheltered sandy anchoring position?
Common questions
What makes a good anchorage?
A suitable anchorage has adequate shelter, depth, holding potential, approach and escape, plus enough clear swinging room for the expected wind, stream and water-level changes. It must also comply with charted and local restrictions.
Is sand always good holding ground?
No. Bare sand can be promising for many anchors, but the exact anchor, size, seabed condition, setting, rode and load still determine whether it holds. Verify the set and continue monitoring.
How large is a yacht's swinging circle?
For a conservative first check, allow for the paid cable plus the vessel's length around the drop point, then consider actual geometry, depth changes and how nearby craft on different systems may swing.
Keep revising this topic
Sources and factual review
Reviewed 20 August 2026 - Coastal Skipper Revision.
Continue studying Anchorwork
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