The Importance of Good Anchoring Technique
Few sailing experiences are as scary as waking in the middle of the night with the wind blowing hard and your boat dragging anchor toward rocks, the shore, or another boat. And one of the most irritating things for most cruising sailors is finding another boat dragging down upon them or getting tangled in their own anchor line.
Good anchoring technique is crucial for safety. Yet all too often even some experienced sailors are in too much of a hurry and skip one of the important steps for anchoring securely. Some new sailors never learn the essentials and just toss the anchor overboard and assume they’ll be fine.
But it is not difficult to anchor correctly and securely in most conditions. Follow these guidelines to help ensure your boat is safely anchored so you can get a good night’s sleep.
1. Prepare in Advance
- Pick your anchorage carefully using an updated chart and paying attention to conditions, including wind direction and speed, likely tidal or other currents, and the forecast. Pay special attention to the chances for a shift in wind direction or speed. If your boat is pulled in the opposite direction during the night because of a reversing tidal current or wind, the anchor may be pulled out.
- The ideal anchorage area should have some protection from the wind and waves and not be against a lee shore in case the anchor drags. The ideal bottom is sand or mud, not rock or heavy seaweed or grass. Most cruising guides and some charts show good anchorages that are protected and have good holding ground. Charts also show bottom characteristics when known.
- Get the anchor ready before making your approach. Whether on a bow roller or lowered by hand from the bow, make sure the anchor rode is free to run. If the anchor rode is not marked at progressive depths with tags or color codes, stretch it out back and forth on deck so that you know how much rode you are letting out when anchoring. To be safe, plan to put out a rode about 7 times the water depth (counting the height of your bow over the water) at high tide.
2. Pick Your Spot Carefully
- After studying the chart and choosing a general protected area, look for a spot with the right depth: from a few feet deeper than the draft of your boat (at low tide) to as deep as 30-40 feet if necessary—if you have at least 200-300 feet of anchor rode.
- Make sure you are well clear of any channel regardless of how the boat swings with wind shifts, and that there are no hazards if your boat were to swing in a full circle around the anchor.
- When other boats are already anchored nearby, follow good anchoring etiquette to stay safe without risking collision or entanglement. The general rule is that the first boat in an anchorage can choose its spot at will and each subsequent boat must stay clear of others already present.
- Calculate how much swinging room you may need if the wind changes, based on how much anchor rode you will pay out according to the water depth. If possible, make sure your swinging circle does not overlap with any other boat’s swinging room.
- In a crowded anchorage where your swinging room may have to overlap another boat’s, choose a spot among similar boats. Most cruising sailboats with a keel will swing in the same direction at the same time and therefore should not collide if not positioned too close together. But a shallow-draft powerboat will swing on the wind differently from a keel sailboat, increasing the risk of collision if their swinging circles overlap.
3. Approach Slowly
- Although you can learn to anchor under sail, most cruising boats lower or furl the sails before making the approach into the anchorage, and anchor under power. Using the engine also gives you more control if a last-minute maneuver is needed.
- Approach your planned spot into the wind, keeping an eye on your depthfinder or chartplotter to ensure you are where you want to be on the chart. If there is a strong current in the area that affects the boat more than the wind, approach into the current instead.
- As you near the spot, slow down to allow the boat to coast to a stop. If you come in fast and have to use the engine in reverse to stop, there’s a good chance the boat may pivot or turn during the reversing, and the boat then will not at first pull directly back on the anchor. There’s seldom any reason to be in a hurry at this point.
- Double-check to make sure you are not too close to another boat and are at the intended depth. If you decide you need to move to either side, circle back around to make your approach again to the new spot upwind or current.
4. Lower, Don’t Drop, the Anchor
- Wait until the person at the helm says the boat has stopped completely and is starting to move backward on the wind or current before lowering the anchor. (Watch your GPS speed if you’re not sure.) If the boat is still moving ahead, you may accidentally set the anchor in the wrong direction by pulling it ahead instead of drifting back to set it.
- It is important to lower the anchor gradually to prevent the anchor rode from falling down on the anchor flukes and possibly fouling the anchor. In that case you may not realize the anchor has not set well, and if the wind comes up later the anchor can easily drag if fouled. Never just toss the anchor over hoping for the best!
- You can tell when the anchor reaches the bottom because of the reduced strain on the rode. Pause a moment to let the boat move back and pull the rode tight. If the boat is floating motionless in the absence of wind and current, tell the person at the helm to put the engine in reverse to start the boat backward. Your goal here is to align the anchor correctly on the bottom, with its shank pulled back in the direction in which the boat will lie at anchor. Otherwise, the anchor chain may foul the shank or flukes and prevent the anchor from setting well.
5. Set the Anchor
- Making sure the anchor is well set (that is, dug in well in the bottom) is the most important part of anchoring. The anchor holds the boat by digging its flukes into the bottom, not by just lying there like a weight on the bottom. If the anchor is not set, the boat may seem well anchored until the wind comes up—when the anchor will then bounce along the bottom as the boat drags toward a hazard.
- As the boat moves backwards due to wind, current, or the engine’s power in reverse, gradually pay out the rode. Always keep a light tension on the line, but don’t yet clinch it tight. (If you tighten the rode too soon, the anchor will be pulled upward and out of the bottom and will not set.)
- Visualize the anchor rode pulling straight back on the anchor shank as the point(s) of the anchor fluke(s) dig in. If your anchor rode is all chain or has a section of chain at the anchor, the pull will be more nearly horizontal along the bottom. This is how anchors are designed to dig in and hold.
- When you have about 3 times as much anchor rode out as the water depth (a scope of 3 to 1), temporarily cleat or cinch the anchor rode at the bow and let it pull tight. Keep a hand on the rode to feel the tension. The boat should stop and the rode feel very tight, indicating the anchor has set. If the anchor has not set, you will feel the tension in the rode come and go or feel its pull changing as the anchor bounces along the bottom.
- If the anchor has set, continue with the next step of paying out scope. If it has not set, you can also continue but must be very careful to ensure the anchor digs in when you have the proper scope. If the anchor has not set yet with about a 3 to 1 scope, many sailors prefer to hoist it now and try again rather than letting out more anchor rode and having to bring it all back up to try again later.
6. Pay Out the Proper Scope
- Continue paying out the rode as the boat moves backward, until you reach the desired scope. Many factors affect the scope needed, including the type of boat, the type of anchor, whether the rode is all chain or a combination of chain and line, the characteristics of the bottom, and the wind predicted.
- As a general rule, most cruisers prefer a scope of 7 to 1 for safe anchoring overnight. For a lunch stop in a calm anchorage, a scope of 5 to 1 or less may be sufficient, assuming someone stays on the boat in case the wind increases dramatically. With higher winds or big waves, a scope as high as 10 to 1 may be appropriate. Remember that the scope should be based on the high tide water depth. If you anchor at low tide in 10 feel of water and the depth 6 hours later is 20 feet, your scope then would be only half of what it was.
- Once you have the proper scope, back down hard on the anchor using the boat’s engine to ensure it is well set. The rode should be very tight and not give at all while backing.
- Scope can be adjusted later if conditions change, simply by letting out more rode if desired. This increases your swinging distance, of course, so you should confirm you will remain far enough away from other boats or hazards.
7. Check the Anchor Periodically
- Even when you’re sure the anchor is well set, changing conditions can result in the anchor dragging. Before relaxing completely for the night, make sure you can tell later on if the boat is dragging.
- Your GPS or plotter can reveal changes of position, although small changes may not be noticeable or may be interpreted as just swinging in a different direction. If possible, take sightings on at least two features on shore (choose something that will be visible at night) and note the compass bearings to each. If these bearings change significantly later, you may be dragging. A smartphone or tablet app like My Anchor Watch can also help ensure you know it if your anchor is starting to drag.
- Another technique used by old-timers is to let down a small second anchor or weight from the stern just to the point where it rests on the bottom, and then drape it over the boom and dangle a noise-maker like a bucket or pot tied to the free end. If the boat moves very far, the line will pull the noisemaker over the boom to clang down into the cockpit, hopefully waking you to take action if needed!
- If you suspect you may be dragging, check the anchor rode at the bow. You may feel or see changes in its tension if the anchor is bumping over the bottom. If you have any evidence of dragging, monitor the situation very carefully. In calmer conditions the anchor may reset, but with gusty or heavy winds it will likely not dig in by itself, and you may have to hoist the anchor and move to a new position and start over.
- Finally, in an emergency situation if the anchor is dragging or a gale puts you at risk of dragging—particularly against a reef or lee shore—you can avert disaster by running the engine slowly in forward gear to take some of the strain off the anchor rode.
A common anchoring problem occurs if the anchor’s flukes hook under a rock, chain, or other bottom debris and prevent the anchor from being hoisted. Try backing pulling the anchor up from the opposite direction in an attempt to free it. The best solution is to use a trip line or the AnchorRescue retrieval device to prevent the risk of losing your anchor should it become snagged.
Anchoring involves a number of skills, which improve with experience. Many books have been written on the subject, and when cruising in unfamiliar waters or far from home where you may be caught in a tricky situation, it’s a good idea to have a book on anchoring or seamanship on board to consult for appropriate techniques in unusual circumstances.