You'll know your anchor is dragging when the references you fixed the moment you set it — two shore bearings or a transit, the depth, your plotter position — start to change instead of holding steady, or the rode goes slack after being taut, or the bow falls off the wind. A GPS anchor alarm backs up that manual check by sounding once you cross a radius sized to your own swing. The first response is almost always to veer more scope and ease the engine, not to panic; re-anchor in a new spot only if that doesn't hold. A wind shift doesn't change your swing circle, but it changes where you sit inside it, so recheck neighbors and depth after any real shift, and keep your anchor light or ball showing so other boats can see you're there. In gusty conditions, a real watch schedule — not just worrying — is what actually catches trouble early.

You picked the anchorage, sized your scope, and proved the anchor was holding — now comes the part that lets you actually sleep: keeping tabs on it. A dragging boat rarely announces itself with a bang; it slips a few meters at a time, quietly, until the bearings you fixed at anchor no longer line up. This article covers the habit that catches a drag early, the real signs that separate dragging from ordinary swinging, how to size a GPS anchor alarm so it actually helps, what to do the moment you confirm you're moving, and the light or shape that tells every other boat you're anchored. If you haven't chosen your spot or set your scope yet, that's lessons 12.2 and 12.3 — this picks up once the anchor is down and proven.

Record Your Baseline the Moment You're Set

The moment your anchor is set and proven — not before — is when you record your baseline, and it takes under a minute. Pick two objects on shore that form a natural range, a transit, or take compass bearings on two items off each beam; note the depth; and if you've got a chartplotter or phone, use its track feature to log your exact position. A well-set anchor gives you a physical check too: a foot on the taut rode should feel steady, with no vibration through it. Once those references are down, set your depth sounder's deep and shallow alarms — an automatic backup for the checks you can't watch constantly. None of this catches a drag by itself; it gives you something fixed to compare against later, so a real drag shows up as an unambiguous change instead of a vague feeling that something's off.

Overhead scene of a sailboat just after anchoring, with dashed lines running to two shore marks labeled Transit A and Transit B, a small depth-check mark labeled Depth, and the boat's own position labeled Plotter fix

The Real Signs You're Dragging

Compare against the baseline you just fixed, not against a feeling. If your two shore bearings or your transit start to walk — the relationship between those objects steadily changing rather than holding — you're either swinging as expected or dragging, and a few more minutes of watching tells you which. The rode talks too: a chain that was taut and vibration-free can go slack, or the bow can fall off the wind it was lying into, and either is a real sign, not ordinary swing. It's tempting to judge your position against a nearby boat instead, but every boat in an anchorage swings on its own independent circle — a neighbor appearing to move is no proof you are, which is why a fixed shore bearing beats eyeballing the boat next door. One sailor's account of a real drag shows the signs stacking up together: waking to shoreline lights that no longer looked right, a GPS reporting speed over ground with the anchor still down, and going forward to find the rode no longer attached to anything below.

Overhead scene showing the boat's faded original position, labeled Baseline fix, with dashed bearing lines to two fixed shore marks, and a solid orange dragged position further off, labeled Dragging, with bearing lines to the same two marks now at a visibly different angle

Sizing a GPS Anchor Alarm That Actually Helps

A GPS anchor alarm is a geo-fence: you draw a boundary around your anchored position, in the plotter or an app, and it sounds if your GPS position crosses it. The number that matters is the radius, and it has to be sized against your own boat, not guessed. Plan for a full 360-degree swing about the anchor as wind and current shift, reaching out roughly as far as the rode you've paid out — set the alarm radius smaller than that ordinary swing and it triggers on a normal gust-driven arc, training you to ignore it; leave it far larger than the swing and it buys little warning by the time it sounds. The alarm backs up the manual checks, it doesn't replace them: one well-run anchor watch briefs the crew on exactly what should wake the skipper — the anchor moving a set distance, the alarm sounding, or the transits no longer lining up. Any one of the three is reason enough to go look.

Overhead scene with two concentric dashed circles around an anchor symbol, the inner smaller circle labeled as the ordinary swing circle and a visibly larger outer circle as the alarm radius, with a boat's drag track crossing outside both

Responding: More Scope First, Then Decide

Confirm you're dragging, and the first move is almost always to add scope: veering more rode gives a skipping anchor the flattest possible pull and the best chance to dig back in, while easing off the throttle reduces the load pulling against it. Once the extra scope is out, watch your bearings again to check — deliberately, not by hoping — whether the boat has stopped moving. If it still won't bite, don't repeat the same spot: raise the anchor and re-anchor properly elsewhere, running the approach-lower-pay out-snub sequence from lesson 12.3. A wind shift deserves the same attention even without a drag: your swing circle doesn't change, but where you sit inside it does, and a full reversal can carry you dramatically closer to a hazard than where you started. Recheck your depth and your neighbors' circles after any real shift, and look the rode over for a tangle if the wind has clocked right around.

Overhead scene showing your swing circle, labeled Your swing, around your anchor, with two boat positions on its edge labeled Before and After the shift, next to a neighboring boat labeled Neighbor whose swing circle overlaps yours — the After position sits inside the neighbor's circle while Before sits clear of it

The Anchor Light Rule and an Honest Watch in Gusty Conditions

An anchored boat has its own signal, and it isn't optional: at night, show an all-round white light where it can best be seen (a smaller vessel under 50 metres may show a single light instead of the full pattern), and by day, show a black ball shape instead — the same rule in different light. A vessel under 7 metres anchored away from a channel, fairway, or crowded anchorage is exempted, but showing the light anyway costs nothing and buys real visibility. Ordinary vigilance is enough on a calm, familiar night, but strong or changeable conditions and tight swinging room call for genuinely active monitoring, not just hoping the alarm catches it. A real watch routine is concrete: a rotation of a few hours per person, whoever's on watch wearing a lifejacket with a personal locator beacon and a quiet check alarm every 15 to 30 minutes, and the whole crew briefed on what wakes the skipper. Build it around when drag risk actually peaks — high water and the turn of the tide — and it replaces an anxious, half-awake night with a small number of deliberate checks.

Split scene divided by a dashed line: on the darker left half, a boat shows a small glowing light at the masthead labeled Anchor light; on the brighter right half, the same boat shows a solid ball at the masthead labeled Day shape

Keeping an anchor down overnight comes together from a short list of habits: fix your baseline the moment you're set, know the real signs of drag versus ordinary swing, size a GPS alarm against your own swing circle, respond calmly with scope before anything more drastic, and show the light or shape that tells every other boat you're there. SailStarter's lesson 12.4, "Sleeping soundly: anchor watch & drag," walks through this same sequence hands-on — recording a baseline, telling a real drag from a normal swing, and running the calm, ordered response when the anchor does let go. If you've already worked through choosing your spot in 12.2 and setting your scope in 12.3, this is the lesson that lets you actually sleep once the hook is down. Come try it.