How to anchor properly: how much chain to let out and how to tell if you are dragging

Updated on 9 October 2026 · By Ricard Prehn, professional recreational skipper (PPER), Spanish Yacht Captain (capitán de yate), Yacht Captain up to 200 GT and sailing instructor for over 27 years

How much chain should you let out when anchoring?

At least 3 times the depth: in 5 metres of water, 15 metres of chain. With some wind or if you are staying overnight, 5 times. In bad weather, 5 to 7 times or more. And if part of it is rope rather than chain, more still, because rope weighs very little.

One detail that makes a difference: measure the depth from the bow roller, not from the surface. If your bow is a metre above the water and you anchor in 5 metres, base your sums on 6. To know how much chain you have out, mark it every 5 or 10 metres with paint or coloured markers, or trust the windlass counter if you have one.

Why do you need so much chain?

Because an anchor holds when the pull reaches it horizontally: that way the fluke keeps digging in. With plenty of chain, the last stretch lies on the bottom and its weight acts as a shock absorber. With too little, the chain is taut and pulls the anchor upwards: the fluke breaks out and the boat drags.

That curve the chain makes between the bow and the bottom is called a catenary. When a gust hits, the chain lifts a little, absorbs the jerk and settles again: the anchor barely notices. If the whole chain is already lifted, the gust reaches the anchor in full, and upwards.

Table: metres of chain by depth

So you do not have to do sums with the boat already stopped. The swinging radius is approximate, for a 10-metre boat with its bow a metre above the water:

Look at the last column: going from 3 to 5 times the depth means you need twice as much clear water around you. That is why, in a cove with other boats, it pays to know how much chain your neighbours have out (just ask, it is normal) and not to anchor inside their circle.

So why not always let out all the chain?

Because the more chain you let out, the bigger the circle your boat swings through when the wind shifts. In a crowded cove, too much chain puts you onto the next boat or the rocks. The idea is to let out just enough for the wind there is and the wind there may be, without overdoing it.

The anchoring manoeuvre, step by step

1. Pick your spot: depth, type of bottom and room to swing. See how the others are lying.
2. Approach slowly, bow to the wind (or to the current, if that dominates) and stop over your chosen spot.
3. Drop the anchor from the bow until it touches bottom; do not throw it.
4. Pay out chain gradually as the wind pushes the boat back, up to the planned length. Dump it all at once and it piles up on top of the anchor.
5. Make it fast and give a gentle burst astern. If the boat stops and the bow points at the anchor, it has set.
6. Take bearings on land and set the anchor alarm.

Choosing the bottom: sand, rock and seagrass

• Sand and mud: the best. The anchor digs in and holds.
• Rock: the anchor holds poorly or, worse, jams and will not come out. If you have no choice, anchor with a trip line on the anchor’s crown: it is what lets you get it back.
• Posidonia seagrass: never. It is protected, anchoring on it is banned in many areas and the anchor slips anyway. More in sustainable anchoring.

How do I know if I am dragging?

Pick two landmarks that line up (a lighthouse and a house, a rock and a tree) and check now and then that they still do. If they drift apart, you are moving. It helps to set the anchor alarm on the plotter or your phone, and to feel the chain by hand: if it judders, the anchor is dragging along the bottom.

If you are dragging, do not wait to see if it stops: start the engine, weigh anchor and anchor again, with more chain or somewhere else. And if the wind picks up at night, get up and check: that is when most boats end up on the beach.