The internet (along with every dock-tail party and cruiser potluck) is chock full of anchoring advice. Most of it centers around one anchor being better than another. Curiously, nearly all participants believe that their anchor is the best choice. Sounds like confirmation bias, doesn’t it?
We’ve spent most nights at anchor since we started living aboard full-time a decade ago. Sure, a month here or there at a dock was enjoyed, but we’ve been on the hook most of the time — I’d conservatively estimate it at 2,500 nights on anchor.
We started with one of those popular modern anchors that comes highly recommended. And, yep, we dragged the anchor a couple of times. We upgraded to a new boat and got an even better anchor, but we still managed to drag a few times. Thankfully, we’ve only dragged a few times out of thousands, but it’s still stressful and potentially dangerous.
There are some ground rules about how not to drag at anchor. But the fact remains that it can happen to the best of us. I’m not claiming to be the best at anything; I’m just providing myself up for the internet’s ridicule and unwarranted criticisms. I believe I started from an average place when it comes to anchoring: I’d done a lot of day boating, researched the basics, and read many cruiser horror stories.
I’ve realized that anchoring is far more complex than you give it credit for when you start. Many cruisers set out with the One Good Big Anchor plan: Buy the best anchor, oversize it, and sleep well.
It’s an excellent starting point, but, unfortunately, it’s not enough.
Here’s a look at what we’ve learned from our exciting and boring anchoring adventures and how we continue to improve our technique for the safety and security of our boat — and to ensure a good night’s rest.
What Does It Mean to Drag Anchor?
First, let’s dive into a dragging anchor meaning.
The purpose of an anchor is to keep a boat stationary. When the anchor drags, it means it’s not working, and the boat is moving.
Why is dragging anchor bad? Let us count the ways!
Firstly, if you are in a crowded anchorage, the dragging vessel will eventually cross paths with other boats. You may drag into another boat, causing damage to your boat or theirs. If you’re lucky, you might not hit them, but you still might tangle your anchor line in theirs, which could cause a real mess.
Next, where will the boat stop? If the wind is blowing off the land, your boat might just keep drifting out to sea. As it gets in deeper and deeper water, there’s less and less chance that the anchor will catch again or slow the boat down very much.
If you’re near a sandbar or a shallow beach, you could drag until the boat runs aground. You’ll have to back off or kedge the boat off, but it might be impossible if a strong wind pushed you there. You might have to call a towboat and wait for a higher tide.
If you drag towards a lee shore that isn’t sand, you might lose your boat. Rocky coastlines or reefs and fiberglass boats do not get along very well. If waves are pounding on the shoreline, not only did you pick a bad spot to anchor, but there’s also very little hope of getting the boat off again in one piece.
The possibility that you might drag needs to be taken into account when picking an anchorage. But understanding what causes dragging and how to prevent it will make it a very slim possibility.
What Causes an Anchor to Drag?
Dragging anchor can be a scary and potentially dangerous experience. As a boater, you need to know why an anchor could drag and do everything possible to prevent it. Below, we look at the root causes of anchor dragging, but first, let’s analyze how the type of anchor you use affects your likelihood of dragging.
Types of Anchors
Despite what the anchoring pundits tell you, anchor dragging has very little to do with your anchor of choice and everything to do with your technique.
ANY ANCHOR — ABSOLUTELY ANY OF THEM — CAN AND WILL DRAG IF USED IMPROPERLY.
People have been using “old” style anchors for decades and prevented themselves from dragging. So you don’t have to have a shiny new anchor with a slick online and social marketing campaign.
However, new anchor designs are better than old anchors. They’re designed to work on a wider variety of bottom substrates and, if they drag, at least try to reset themselves.
Bigger anchors are generally better and less likely to drag up to a point. The anchor must still fit on your bow and be within your capabilities for hauling up. And, if it’s too big for your boat, you might have trouble setting it in the first place.
Perhaps more critical than anchor size is using as much chain as you can comfortably carry. Even if you use primarily rope rode, your anchor must still have 20 or more feet of heavy chain. This helps the anchor set and keeps it set.
Old style or traditional anchors:
- CQR
- Bruce or generic claw
- Delta or generic plow
- Fortress or generic Danforth
- Fisherman
New styles or modern anchors:
- Mantus M1 or M2
- Rocna or Rocna Vulcan
- SPADE
- Ultra
Root Causes of Anchor Dragging
Anchors can fail and start dragging for a couple of reasons. Equipment failure could cause it — a lost shackle pin or a broken swivel could cause a complete loss of your anchor. Always check the seizing wire on anchor shackles every time you launch it, and use only the highest-quality hardware you can get.
Assuming nothing is broken, then the anchor could drag for one of three reasons: not enough scope, poor holding ground, or a sudden wind shift.
Angle of Pull (Insufficient Scope)
An anchor is designed to hook into the bottom at a specific angle. For maximum grip, any force of pull on the anchor must be made (more or less) horizontally. If you pull up on the anchor (toward the water’s surface), it will come out of the bottom and drag.
So, the first step to ensuring that an anchor does not drag is to ensure that the pull on it is horizontal, along the bottom, and not up toward the surface. We do this by putting out adequate scope — the ratio of anchor chain or rope to water depth. The normal minimum scope for chain rodes is 5 to 1; for all rope rodes, it is 7 to 1. If conditions are rough, you can increase the scope until you reach the normal for storms, which is 10 to 1.
However, it’s an oversimplification to say the scope is calculated based on water depth. Water depth changes with the tide. Many boaters have anchored with a 5 to 1 scope at low or mid-tide, only to discover they are under-scoped and dragging at high tide.
The height of the boat’s bow over the water must also be factored in. Most small boats are only two or three feet off, but that makes a difference of up to 15 feet if you’re putting out a 5:1 scope. If your boat has a high bow, it might mean a lot more.
To put out the right amount of scope, you must know how much of the anchor line is out. There’s no way to accurately do this unless you’ve measured and marked your anchor chain/line. There can be no guessing, no counting seconds or chain links as they pass off the roller, and no rough estimates or guesswork. It just doesn’t work — you must have a marked rode and know precisely how much line is out.
We’ve marked our chain with spray paint and sewn-on markers every 25 feet. This keeps it pretty simple, and the increments work well. We always err on the side of putting out too much rather than not enough.
Bottom Composition (Poor Holding Ground)
The next problem that can cause dragging is the type of bottom the anchor finds. In some areas, it’s nearly universal, like in the Chesapeake Bay, where it’s always sticky mud. But in places like the Bahamas, you might find scoured rock, thick grass, thin weeds, or deep sand all within a small area.
Most boaters know that some anchors are better at holding in some types of bottoms than others. A common recommendation is to carry several types of anchors to anchor in several kinds of bottoms.
But in my experience, it doesn’t work out that way. Or at least, the thinking needs to change a bit with modern anchors. Modern anchors are designed to work on as many different bottom types as possible, so the result is simply that there are some places where you just can’t anchor.
When the holding ground is poor, nothing can make an anchor hold.
The absolute worst place to anchor is on smooth rock. The anchor just bounces along the bottom. Even if the tip gets hooked a little, it doesn’t take much to get it loose (a wind shift or even a good bounce from the boat due to a wave).
The next worst place to anchor is on thick seagrass. Some anchors will bounce off the grass, while others dig in by the tip. Even if they bury into the grass, it will pull out from its roots with enough force. This is especially bad since it might seem like you’ve anchored fine and that the anchor is set well. But then a thunderstorm comes along, the grass pulls out by the roots, and you’re left drifting with a clump of grass on the end of your chain.
The third worst situation is a little less predictable. This is when things on the bottom foul an otherwise good anchor and keep it from setting. Weeds and kelp can do this, as it can wrap around and clog the anchor so its fluke doesn’t set into the bottom. Small rocks can also do it if it’s just the right size rock.
The best places to anchor are places with sand or mud on the bottom. Modern anchors handle this just fine, and they operate predictably. Even if the bottom is soft or silty, you can usually get the anchor to dig deep enough into the solid stuff farther down.
Wind or Current Direction Changes
If you’ve done everything right, the final thing that will get you is a sudden wind shift.
You must realize that anchors are designed to be pulled on horizontally, along the bottom, from behind — like a plow through a field. The more you pull, the deeper the anchor is set in — at least theoretically. As you pull on it, it will move a bit as the anchor digs down. This isn’t dragging; this is it setting.
But what happens when you pull on the anchor from a different direction? This is what happens when the wind shifts.
The most dramatic example happens every winter and spring when cold fronts begin moving through the southeastern US. The fronts are well forecast, so boaters find a protected place for the storms. Ahead of the front, winds are out of the southeast or south. Anchors are set, and everyone is very comfortable.
Then, the wall of ominous shelf clouds appears on the horizon as the skies darken. As they approach, the winds become dead calm. The boats drift around on their anchor chains, anxiously watching the approaching squalls.
From dead calm, the squall line brings a sudden gust front with winds from the north-northwest. With a strong front, gusts of 50 knots are not uncommon, and hurricane-force gusts have happened.
So, from the anchor’s standpoint, it was set for moderate winds from the south. Now, storm-force gusts hit from the north. The boat, swinging on its chain, drifts immediately downwind until it gets to the end. The chain tugs on the anchor, but it’s backward — it is now stretched out in front of the anchor.
Every anchor will likely come out of the bottom in this scenario. Once the anchor is free, it drags along the bottom. Then, one of three scenarios plays out:
1. Best-case scenario
The anchor pops out, then drags a few feet before grabbing and resetting itself. The distance moved is probably only noticeable on a GPS chartplotter, unless you were anchored to close to another object to begin with.
2. Scenario #2
The anchor pops out, and the boat drags some distance. Something keeps the anchor from digging in: Perhaps the boat is just moving too fast, and it bounces along the bottom, or there’s not enough scope out for the storm conditions, or the anchor is upside down now and isn’t turning over, or something has clogged the anchor, or, or, or. A million different things could keep the anchor from immediately grabbing, but in this scenario, it does eventually reset.
3. Worst-case scenario
The anchor pops out and is prevented from resetting by any of the factors above. The boat continues to drag in the storm until the winds die down or until the boat is aground or stopped by something else.
Modern anchor companies would have you believe that scenarios 2 and 3 are impossible — that their anchors are so good they will always reset immediately. It’s unrealistic and, in my experience, utter balderdash. At best, a modern anchor will more often keep you in scenarios 1 or 2 than a traditional anchor.
The problem is, of course, that when it happens, it’s a shit show. It’s 2:00 am, pouring ice-cold rain and blowing 50 knots in your face. You’re struggling to get the anchor up, throw out another, or motor into the wind. In most sailboats, full throttle is barely enough to get the boat to point into 40-knot winds, much less anything more.
If there is one for the poor draggee, the silver lining is that these squall lines move through as quickly as they come. Within five minutes, conditions have usually moderated back to a manageable amount.
We witness this precise scenario play out in anchorages along the ICW and Bahamas every season. Summer thunderstorms can be even worse because they pop up within an hour or so without much warning.
The only surefire way to prevent dragging in the scenario described above is to set two anchors, one set for the south winds before the front and one well-set in advance of the north winds that come after.
What Are the Signs of Anchor Dragging?
To understand what your boat will do when it drags, go out on a day with wind, space to maneuver, and no one around. Drive the boat dead into the wind, then put the engine in neutral and let it drift to a stop. Most boats will soon find themselves drifting downwind, with the bow falling off one way or another. On some boats, the bow will fall off the wind suddenly.
When you’re at anchor, the same thing happens. But the bow moves one way until the anchor chain stops it. Then, you usually start to swing the other way. However, if the anchor isn’t holding, the bow will fall off, and the boat will continue dragging backward. Unless there’s another boat nearby, it can be hard to determine precisely what is happening. But it will feel bizarre that the bow is not swinging back the other way.
There are two basic ways to confirm if your anchor is dragging: visually or electronically.
Visually, you must use ranges. A near object and a far object, perpendicular to your path of motion, will appear stationary in relation to one another if you aren’t moving. If you are dragging, the background will appear to be moving behind the near object. Pilings are the best range markers. Other boats could be dragging, making it even more confusing.
Electronically, you might look to your GPS if you have it up and running. If it’s tracking your path, you’ll see your normal swings drawn on the chart. A dragging incident will be distinctive, and your speed will likely indicate a problem (although it’s never 0.0 knots on the GPS, at least not on mine).
There are also apps you can use. One of our favorites, Aquamap, has a built-in anchor drag alarm. You can set an alarm radius, and it draws your tracks on the maps to visually see where you’re normally swinging and if anything has changed.
What to Do When an Anchor Drags
Now that you know what causes anchor dragging and how to identify it, what should you do about it?
First, prevention is better than any cure. You must learn to plan for the weather conditions and anchor so that you are confident you will not drag. Otherwise, you will never have faith in your anchoring skills or gear. As previously noted, sometimes this means you must consider using more than one anchor, even if you have the shiniest new modern anchor that promises never to drag.
But let’s say you are dragging in a storm and need to save your boat. The first step is to get the engine on and motor into the wind. This should stop the boat’s motion and at least take the load off your anchor chain. Try not to motor forward and run over your chain, but in an absolute shitshow, it can be challenging to control a wandering boat. If you can get it under control, you may consider getting to the bow and raising the dragging anchor. You might consider dropping the anchor to escape if you can’t get it up. If you have time, you could buoy it to find it later. Once the anchor is handled, you can motor to safety, driving around until the storm passes or re-anchoring somewhere safe.
If motoring isn’t an option, sailing to safety may be technically possible. But this would only work if you are an outstanding sailor, with the boat ready to go and fit enough to sail in the given conditions. You’d need the sails ready to hoist (no covers) and enough room to tack out into open water during the storm. It’s asking a lot at the best of times, and it is probably better not to be considered by most cruising sailors.
If all else fails, you could drop a second anchor and hope it holds. We keep two bow anchors ready to deploy, our primary and our backup.
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