Anchor not holding: why a yacht drags and what actually decides it

An anchor doesn't hold by weight. It holds by chain length, seabed type, and how it was set. Weight is the fourth most important factor, which is exactly why boats with big anchors still drag on a regular basis.

Let's go through what actually decides it.

The main number: how much to pay out

An anchor works when the chain lies horizontally at the seabed. That pulls the shank along the bottom and makes it dig in. The moment the chain starts pulling upward, the anchor comes out of the bottom — no matter how much it weighs.

That gives a simple rule, and it matters more than everything else.

Scope (rode length to depth ratio):

• at least 5:1 — a normal chain anchorage in calm weather;
• 7:1 — if the wind is fresh or a blow is expected;
• 10:1 — a storm anchorage;
• add extra length to a combination rode if you're on rope with a length of chain: it's lighter and holds its shape less well.

And measure depth from the bow roller, not from the surface: that's freeboard plus depth under the keel. On a boat with a high bow the difference adds up to a meter and a half or two.

The most common mistake at anchor is paying out three-to-one "by eye" because boats are anchored close together. That's not anchoring — that's hoping it won't blow.

The seabed matters more than the anchor

The same anchor holds very differently on different bottoms, and the difference is enormous.

• Sand — the best holding ground. Holds almost anything, predictably.
• Mud and clay — hold well, but the anchor needs time to dig in. Don't load it up right away.
• Grass and weed — the worst case. The anchor sits on top of the mat and skates. Look for patches of bare sand: with a mask, or by the color of the water.
• Rock and shingle — holds only by snagging, by chance. It can hold fast, or not hold at all, and it's hard to break free afterward.
• Coral — don't anchor there. It holds poorly and you must not damage it.

Check the chart: seabed type is usually marked on it. Five seconds of reading saves you a bad night.

How to set it

An order of operations that works, with nothing extra in it.

1. Run over the spot and check the depth, the seabed, and how neighboring boats lie.
2. Head up into the wind and bring way to zero.
3. Lower the anchor, don't drop it. An anchor dumped in a pile lands on its own chain and won't dig in.
4. Drift astern slowly under light engine power, paying out chain evenly. The chain should lay out in a line, not a heap.
5. Once the calculated scope is out, snub the chain and reverse at moderate throttle for about twenty seconds.
6. Watch the shore. Line up two landmarks — if they drift apart, you're dragging.

Step five is the one most often skipped, and it's the only one that honestly answers whether the anchor is holding. Thirty seconds astern in the evening buy you a quiet night.

How to tell you're dragging

• Two landmarks on shore that were lined up drift apart.
• The boat lies beam-on to the wind and stops yawing — often the first sign.
• The chain jerks in fits and starts instead of pulling steady.
• A shudder runs through the chain, felt by hand at the bow.
• An anchor alarm goes off on an instrument or a phone.

A phone anchor alarm is the cheapest safety upgrade there is. Takes a minute to set up, wakes you in time.

If you've dragged at night

A sequence to follow so you don't have to think it through in the dark:

1. Start the engine. Before anything else.
2. Wake the crew and turn on deck lighting.
3. Motor into the wind to take the load off the chain and stop the drift.
4. Bring the anchor all the way up, don't try to reset it while under way.
5. Move to clear water and re-anchor from scratch, with proper scope.

What not to do: try to "pay out more chain" while adrift. While you're paying out, the boat keeps moving, and it's usually moving toward a neighbor.

Anchoring near other boats

• Everyone should be on the same type of rode. A boat on chain and a boat on rope swing differently, and they converge when the wind shifts.
• Work out your swing radius — that's the length of chain paid out plus the length of the boat. Your circle shouldn't overlap anyone else's.
• Last to arrive, first to move. That's the general rule, and there's no point arguing with it.
• Don't anchor directly over someone else's chain. When you weigh anchor you'll bring theirs up along with yours.

What to check on the ground tackle itself

Once a season, and ideally before every long passage:

• The connecting shackle between anchor and chain: is it moused, is the pin worn.
• The swivel, if fitted: does it turn freely, any cracks.
• The chain markings. Without markings you don't know how much you've paid out, and the five-to-one rule doesn't work.
• The bitter end lashing in the chain locker. It must be there, and it must be cuttable with a knife: if you ever have to let it all go, there won't be time to hunt for a tool.
• Chain wear at the anchor — that's where it wears fastest.

What to measure if you need a part

Ground tackle is built entirely around chain gauge, and "close enough" won't run through a windlass gypsy.

• Chain gauge — link thickness with a caliper.
• The windlass gypsy, close up, ideally with the chain sitting in it.
• The windlass nameplate — maker and model.
• The shackle and swivel next to a ruler.

With this set of measurements the right chain, shackle, and windlass parts can be sourced, even for a model long out of production.

In short

Pay out at least five to one, measured from the roller. Check the seabed on the chart and with your own eyes. Lower the anchor, don't drop it. And always check by backing down — it's the only honest proof that it's holding. Everything else is hope.