Boat Anchoring Techniques Explained (Illustrated Guide)
The basics of anchoring in calm conditions in an anchorage with good holding aren't difficult to master, and you should start with basic anchoring techniques if you haven't read it already and practiced setting your hook.
This article is for when anchoring isn't so easy, but you still have to stop your boat and stay secure. There are several approaches you can take for anchoring in tricky bottoms, bad weather, or in other special situations where conditions are less than ideal.
Your tools are skills and equipment, and a little advance preparation can give you a lot of options.
In this article:
Solve Difficult Bottoms with Different Anchors
We can solve most challenging bottoms with a different choice of anchor, but that's not always an option since you can't stock your bow locker with every type of anchor on the market. Most sailors have two anchors - a primary all around anchor, and a backup. When choosing your backup anchor, make sure it's different from your primary, since two anchors of the same type don't buy you anything with varying bottom conditions.
With most tricky bottoms, more scope is always better than less. So if your anchorage has the swing space, add an extra helping of rope or chain when you set.
Most difficult bottom: rocks
Rocky bottoms and solid rock are probably the most difficult anchoring, since it's nearly impossible for an anchor to cut into the bottom and set. Solid rock is trickier than a rock strewn bottom, and nearly impossible to get a good holding without a lot of weight. A spade or plow can find something to dig into with a rocky bottom, but not much can hold on solid rock.
The fisherman's anchor is a good choice for rocky bottoms, since it relies more on weight and catching than on digging in like fluke and spade anchors. Mushroom anchors can work, but both mushroom and fisherman's anchors must be heavy to hold, since the weight of the anchor has to do a lot of the work.
As an alternative to anchoring, consider using things on shore like trees and other fixtures with a deep water stern anchor. If you can get a stern anchor to set outside the rocks, you can run a line to shore and keep your boat in place.
Use a trip line instead
And if you know you're anchoring in rocks, consider using a trip line. Or if you have a slotted anchor shank, like you'll find on a Rocna, Manson, or other modern anchor, be sure to move the shackle there before you drop anchor - it will help you recover it and decrease your chances of getting stuck fast.
Anchors don't dig in in soft silt
Anchors tend to just sink into silt and soft mud, then drag through without digging in when you try to set them. Thick silt isn't much thicker than water at the top of it, and your anchor has nothing to catch. Anchoring in a really soft bottom requires patience, since your best technique is to let the anchor settle into the soft mud before you try to set.
Drop your anchor in the selected spot, but when you get some scope out, let it sit for a while. A long while - in some places it can take fifteen to thirty minutes for your anchor to sink through the ooze to reach med think enough to catch.
Once you're gotten your anchor nestled into the silt, try setting it gently. Idling back on it in reverse should help it catch in the thicker mud under the soft stuff. Avoid a final "hard set" with this bottom type unless you're expecting some wind.
Avoid false sets in weeds and grass
Like rock bottoms, your best choice for a weedy bottom is an anchor which works well in weeds. Some anchors can not cut through the tough mat of roots and fiber under a weed bed, or have flukes which tangle in the vegetation instead of digging in.
Roll bar anchors will work
Modern roll bar anchors do pretty well in weeds and grass, but some plow and fluke anchors can be quite difficult to set. If your primary anchor is a CQR, fluke, or other anchor known to fare poorly in grass and weeds, try another anchor if you have one.
One caution - even the best anchors for grass and weeds may "false set" on you. They can catch on the grass and weeds and feel like they've caught bottom, but if they load up or the wind shifts, you may have troubles. Take extra care to back down hard to make sure your anchor is dug into the bottom.
Avoid coral heads if you can
Coral heads or "bommies" are in tropical anchorages all over the world, and some remote atolls give you no choice but to anchor near or among them. Anchoring badly among bommies can cause a mess - your anchor chain will get snaked and wrapped through and around the coral heads. Not only is this hard to get out of, but it is terrible for the coral and you should avoid it.
Set up floats
The first thing to look for around coral heads is a large patch of clear sand to drop your anchor. It may be tough to find, but you don't want to drop your anchor on top of hard coral. You won't be likely to find enough open sand for your whole swing range, so you'll need to rig up some floats to keep your chain out of the coral.
Your goal is to get the last 1/3 of the chain to hold you on the bottom, but use your string of three or more fenders to keep the rest of the chain suspended in the water above the coral heads. Your fenders will almost completely sink while you do this, but they will keep the chain from getting tangled.
Start by making your initial drop on that patch of clear sand and let up from one third to one half your expected rode out. Then tie a fender to the chain with a stout line and let out another 1/3 of the remaining rode. Tie on another fender, and let out another 1/3 of the remaining rode. Tie on a third fender, and let out the remaining rode and snub it.
Dealing With Tough Anchoring Conditions
Anything which reduces visibility and hearing, adds shifting forces on the boat, or increases the loads on your anchor will add a challenge to your successful anchoring. If you plan and practice, you can get through it and get a good set.
Communication is key when you have someone on the bow and someone on the helm, and well-practiced hand signals are a must. Headsets can help, but if you use them, make sure you have hand signals to back them up.
Prepare in case of heavy weather
Anchoring in bad weather is fraught with difficulty. Driving rain cuts visibility, howling winds can make communication near impossible even with headsets, and heavy wind will drive you out of position quickly as you try to get the anchor down to the bottom.
The best first step to anchoring in bad weather is to talk your plan out ahead of time. You may have trouble communicating with the person on the bow, so if everyone on board knows the plan for anchoring, you'll do better if you can't hear each other or see hand signals. Heavy weather anchoring cuts across a lot of the tough conditions in our list, but if you're trying to escape a bad weather system, you may have little choice but to deal with it once you've ducked out of open water into a more protected anchorage.
High wind will make positioning hard
High wind causes several problems anchoring. The first is the effect on the boat - with a lot of wind, your boat's windage is much more pronounced, and as you slow down to anchor, it becomes harder to hold the boat on station and put the hook where you want it. Your bow is much more likely to fall off, and while idling into position you may even get blown to a stop or pushed backwards. If you stop, you lose the ability to steer and the wind may push you out of position.
When holding station to drop anchor, try these tips:
- Use a little more engine power and come up to your anchor drop point with a little more speed to maintain steerage. Not a lot more, but an extra knot can keep your ability to steer.
- You will blow backward quickly, so don't let the boat fall back until you've got enough rode out to hit bottom. Use small pulses of the engine forward to stay in place without overrunning the chain.
- If you have main furling, cheating a tiny amount of sail out can help keep you pointed into the wind, like an anchoring sail on your stern might. You don't want too much sail area, since it may start driving the boat forward or even cause heeling. But a small triangle can help keep the boat in irons so you aren't swinging all over as you drop.
Communication will be harder
The other complication is communication - wind won't affect your hand signals, but wind noise can mess with radios by causing a loud hiss in your microphones that drowns out voices. If you use headsets with foam wind mufflers, make sure they're installed. If you don't have them or are using handhelds, a little piece of cloth can cut that wind hissing right out. A thin sock slipped over a handheld radio looks silly, but does a great job muffling wind noise.
Low visibility requires lights or radar
You can lose your visibility in heavy rain, fog, or darkness. Your solutions for each are a little different, as is the impact.
The primary risk of using hand signals without radios is lost visibility; if you can't see the bow, you can't communicate. In darkness, the fix is easy. Make sure bow and helm people have lights, and shine them on your hands when signaling (and not in each other's eyes!). Headlamps work well for this, since helm and bow both need their hands.
Lights won't help you in driving rain or fog, there you will need to do your best with hand signals or use a waterproof radio on the bow. Fortunately, rain and fog are rarely heavy enough to block vision from the helm to the bow, but if it is talking, your plan out first is critical.
If you have radar, make sure it's on when you come into an anchorage in poor visibility, and zoom it in far enough to distinguish boats and estimate distances. While everyone should have lights, we all know there's no guarantee of it. And judging distance from anchor lights in the dark is difficult. Whether it's fog, rain, or dark, your radar can light up the boats around you and give you a clue about their relative positions as you pick your place to drop anchor.
Tidal currents may cause drag
Dropping in tidal currents isn't difficult, but staying anchored can be. A strong pull in one direction can give you a great set, but when the tide changes and starts ripping a couple of knots in the other direction, it can pull your anchor out and cause you to drag.
When anchoring in a tidal zone, always note where you are in the tidal cycle - how much time until the next high or low, and which way it's moving. For the most extreme tidal currents, consider a Bahamian Moor with your two anchors in line with the current. For more details, see our article on using two anchors.
REMEMBER - most places with tidal currents also have a pretty big tidal swing. When you figure out your scope, you need to calculate your ratio from the top of high tide, so you don't get caught up short if you anchor near low tide.
If you anchor with only one anchor, take care to set extra hard, and use extra scope if there is room. Expect your anchor to reset every tide cycle, so the extra rode will give it time to re-bury itself, or even keep it from resetting.
Avoid anchoring in deep water in bad weather
Anchoring out in deep water always feels like standing on the edge of a cliff; there was never quite enough grip to really rest or feel comfortable. But sometimes, you have no choice - it's all there is, but it may be a little nerve-wracking.
If you have an all-chain rode, you can anchor in water up to about 1/3 of your rode length in calm and settled conditions. The conditions are the key - if you can not get out enough scope for wind and weather, you should not stay in a deep anchorage if bad weather develops.
For more detail, check out our article on deep water anchoring:
How to Anchor a Boat in Deep Water (like the ocean)
Other Situations That May Prove Difficult
Sometimes, anchoring isn't so hard, but once you get settled in, you realize things aren't as comfortable as you hoped. When we dropped anchor at Santa Cruz in the Galapagos, it was comfortable when we arrived. But a few hours later, the ocean swell started coming in, and the wind on our bow kept us pointed across the incoming rollers, resulting in a sickening side-to-side roll as the boat swung at anchor.
This is avoidable.
Roll and Chop
If you're in an anchor with a lot of roll in it, set a stern anchor to point your bow into the roll and chop instead of letting your boat swing in the breeze and roll side to side. The up and down motion is much easier on your inner ear and will let you sleep at night. Don't worry about swinging into the wind unless you're expecting bad weather. But if you're expecting bad weather, an anchorage subject to swell isn't a good place to be, anyway.
The key is to keep the roll from hitting the side of your boat and creating that horrid motion.
Anchorages can be tight in two ways - they can be crowded, or they can be small or narrow. For crowded anchorages, look at our specific advice on handling a crowd.
With a tight anchorage, you don't want to risk swinging into shallows or bumping into rocks or other hazards. Fortunately, there are a few ways to deal with this.
- Use a stern anchor
- Try a Bahamian Moor if there is room; it should keep your boat swinging on a single point.
- Tie one or more lines to shore to stop you from swinging.
The goal of these approaches is to keep your boat fixed in position or in a very limited swing radius. The best tool will depend on where you are anchoring and how much space you have with sound things to tie off to.
Special Gear (How & Why to Use It)
The market is awash with products to help you anchor more easily, but do they all work? The short answer is that some of them can help you, in some circumstances, but the effectiveness of some of them is debatable. And you can cause difficulties if you misuse them.
A kellet is a weight you attach to a midpoint in the catenary on the anchor rode. The theory is that it pulls the rode down more sharply to the bottom and gives a better angle of attack for pulling loads on the anchor shank. This is supposed to help increase holding power. Evidence and testing shows that once the wind blows hard enough to straighten out the rode, the effect of a kellet goes almost to zero for adding holding power.
That doesn't mean they have no value, especially with rope/chain combination rodes. A kellet can reduce the swinging and dancing your boat does at anchor by holding the rode down. But don't expect it to perform any miracles for you while anchored out in a forty-knot blow.
Anchor swivels eliminate twisting in the rode when you pull up the anchor. Some anchors are prone to spin like propellers when they hauled through the water, and this can put an undesirable twist in chain and rope. Too much twist can cause binding and knotting, and make pulling the anchor up in the right orientation to slide into the bow roller challenging.
If you are experience twist in your rode, look into swivels. Some manufacturers suggest them for their anchors, so heed their advice if you choose their anchors.
But an unnecessary swivel adds another weak point to your anchor rode, so if there is no need for one, don't add it. It's one more moving part to corrode, seize up, or break.
Trip lines are handy ways to get leverage on our anchor from points other than the end of the shank where the rode attaches. Many anchors provide extra loops, rings, and attachment points for a trip line, and they can be very helpful with obstructions on the bottom. Everything from rocks to discarded junk can catch on your anchor, and pulling a plow from the front may be a better way to dislodge it than hauling straight up on the shank.
You can rig trip lines with a float, or a line can be secure to the rode when the anchor is set. Either way, you need to take some care that the trip line doesn't tangle into the anchor or break loose until you need it.
Marking a trip line with a float is an easy and convenient way to keep your trip line clear of the business end of the anchor, while making retrieval easier since you'll know exactly where your anchor is.
But they will make you very unpopular in a crowded anchorage, and you should only use them when there is plenty of space around you.
Remember - everyone swings together in a crowded field, and there will be times when your boat will swing right over someone else's anchor. If that anchor has a floating ball and a line on it, there's a risk it can bang your boat or get fouled on your rudder or propeller. A marker float increases how much open water you and your boat take up, and few people use them for this reason.
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