The ten most common anchoring mistakes
Too little chain, the wrong seabed, an anchor never set, the windlass holding the boat: the ten mistakes that most often make anchors drag – and how to avoid each one.
The short answer
Most anchors do not drag because the anchor is poor, but because something goes wrong during the manoeuvre: too little chain, the wrong seabed, an anchor that was never properly dug in. The ten mistakes below are the ones that happen again and again in every bay. Each of them is easy to avoid.
1. Sizing the chain by the water depth
"Three times the depth" sounds like a rule but calculates wrongly. The chain does not start at the surface but at the bow roller – and where there is tide, what counts is the depth at high water, not at the time you anchor. Laying five times the depth in 4 m of water with a bow roller 1.5 m above the surface actually gives you only 3.6 : 1.
Better: (water depth + tidal rise + bow roller height) × scope. How much anchor chain for which depth? works out the metres for you.
2. Choosing the scope by the weather while you anchor
When you anchor in the afternoon, it is often calm. What matters is what comes during the night: a wind shift, katabatic gusts off the mountains, a thunderstorm. Anchor for the calm and you are lying too short for the blow.
Better: Read the forecast for the whole stay and choose the scope from that – at least 5 : 1 with all-chain overnight, 7 : 1 if strong wind is forecast.
3. Not knowing how much chain is out
The best calculation is no use if nobody at the bow knows whether 40 or 55 m have gone out. People estimate from the sound of the windlass, from counted seconds or from markings that wore off long ago. The estimate is almost always too high – there is less chain out than you think.
Better: Mark the chain every 10 m, with a method you can still recognise at night – which methods last is compared in Marking anchor chain: six methods compared. More precise still is a display that shows the metres right at the windlass; that is what we are developing AnkerSepp for, see Chain counter without installation.
4. Not looking at the seabed
Sand and firm mud hold well. Seagrass, especially Posidonia in the Mediterranean, holds poorly: the anchor slides over the dense mat instead of digging in. Rock either does not hold at all or holds so well that the anchor will not come up again. On top of that, Posidonia meadows are the nursery of countless fish species and are therefore protected in many countries – anchoring on them is prohibited there.
Better: Check the chart and the pilot book for what is on the bottom, and look down before you drop. A light patch of sand between dark seagrass is the spot you want.
5. Forgetting the swing circle
A boat at anchor does not lie at one point; it swings around the anchor. The radius is as large as the stretched-out chain plus the length of the boat – with 50 m of chain and a 12 m boat, more than 60 m. Anchor too close to a neighbour, a reef or the shore and you will only notice when the wind shifts at night.
Better: Estimate your swing circle and anchor so that it stays clear. Watch your neighbours: a motorboat on rope swings differently from a sailing boat on chain. Whoever was there first has priority.
6. Dumping the chain in a heap
If the chain is dropped in one go while the boat is stationary, it lands in a pile on top of the anchor. The anchor cannot orient itself, the chain may foul around the shank, and at the first pull it breaks out again.
Better: Drop the anchor as the boat comes to a stop, then pay out the chain steadily while the boat drifts or motors slowly astern. That way it lies stretched out along the bottom.
7. Not setting the anchor
An anchor that just lies on the seabed does not hold. It has to dig in – and that only happens under load.
Better: Once the chain is out, build up load with slow, then increasing reverse. Pick two transit marks ashore that line up: if they do not move against each other, the anchor is holding. If the chain jerks or the transit drifts, the anchor is not set – re-anchor, don't hope.
8. Letting the windlass hold the boat
The anchor windlass is built to lift, not to hold. If the boat hangs on the gypsy overnight, every shock from gusts and swell ends up on the gearbox, the bearings and the deck.
Better: Take the load off the windlass – with a chain stopper or a snubber: a chain hook on an elastic line that is made fast on a cleat. It takes the load off the windlass and cushions the snatches that a taut chain would otherwise pass straight to the anchor.
9. Bow and helm not communicating
At the bow the windlass is running, at the helm the engine, and between them are ten metres, wind and engine noise. Shouted commands arrive half-heard, and whoever is at the helm without knowing how much chain is out goes astern too early or too late.
Better: Agree hand signals before the manoeuvre: anchor down, pay out, stop, reverse, anchor holding. And show the length paid out with your fingers – or read it where the chain runs.
10. No checks through the night
An anchor that holds at six in the evening will not necessarily hold at three in the morning. Wind shifts and tide change the direction of pull, and an anchor that breaks out once rarely digs itself back in.
Better: Note bearings after anchoring and set the anchor alarm on the plotter or in an app. In strong wind, set an anchor watch. And secure the bitter end in the chain locker with a line you can cut in an emergency – so that the chain does not go overboard if you drag.
To take away
| Mistake | Better |
|---|---|
| Chain sized by water depth | depth + tide + bow roller, then × scope |
| Scope chosen by the weather while anchoring | by the forecast for the night |
| Chain length estimated | mark it or read it |
| Seabed not checked | check the chart, look for a sand patch |
| Swing circle forgotten | keep stretched chain + boat length clear |
| Chain in a heap | pay out steadily while the boat drifts astern |
| Anchor not set | build up load in reverse, check the transit |
| Windlass holds the boat | chain stopper or snubber |
| Commands shouted | agree hand signals |
| Night without checks | anchor alarm, bearings, anchor watch |
None of these mistakes has anything to do with expensive gear. They happen in the few minutes of the manoeuvre – and that is where they can be avoided.