Anchoring techniquesDec 28, 2017
A tool kit of basic anchoring setups for the voyager
Robin Urquhart’s sloop Monark anchored in Mexico.
We have learned many anchoring techniques the hard way. One of the worst occasions saw us wrap three times around an old mooring block during current changes in La Paz, Mexico. After hours of troubleshooting and a dive into brackish fast-moving water, we sailed around three times in a counter-clockwise direction and were freed. If we had turned the rudder from one side to the other after each current switch, we never would have had the problem in the first place. On another occasion, we rolled so violently in swell that we didn’t sleep a wink and I was tossed from the bed.
There are a few techniques for anchoring in swell, current, foul ground and strong wind that can improve safety and comfort.
Anchoring in swell
Anchoring in an area subject to moderate ocean swell can be very uncomfortable. The boat will roll violently in swell that is more than 45 degrees off the wind angle. It can also be uncomfortable with the bow or stern directly into swell, as the pitching and plunging causes the transom to smack the surface of the water. The most comfortable position for the boat is between 15 to 35 degrees off the direction of the swell. This can be accomplished in two main ways.
The winch bridle: The simplest solution is to set up a winch bridle. A line is tied to the anchor rode with a rolling hitch and taken back to a cockpit winch where it is tightened. This changes the angle of the boat relative to the wind. The downside of the wind bridle is that the boat may begin to “sail” forward due to windage on the side of the hull. In such a case, it is better to deploy a stern anchor.
Setting up a winch bridle:
1) Set the anchor.
2) Back down on the anchor to make sure it is secure.
3) Tie a line to the anchor rode using a rolling hitch and bring it back to a cockpit winch. Release approximately 20 feet of anchor rode. Winch in on the second line to change the angle of the boat relative to the wind. By playing around with the lengths of the anchor rode and winch bridle, you can adjust the angle of the boat.
The stern anchor: More effecting than the winch bridle but more work to set up is the stern anchor. The stern anchor provides more security and is better at creating a stable angle.
Setting a stern anchor:
1) Set anchor 1.
2) Back down on the anchor to ensure it is secure. Pay out more anchor rode than the intended scope to facilitate setting anchor 2 (stern anchor).
3) Take out anchor 2 in the dinghy to a minimum 5:1 ratio. Drop the anchor.
4) Take in the slack of anchor 2 and use a cockpit winch to set it. Winch in anchor 1 to the desired scope and pay out the line on the stern anchor. Keep both anchors relatively taught to maintain location and angle of the boat.
Anchoring in current
The Bahamian moor: This is an effective way of anchoring in a strong current. It consists of two anchors off the bow — one set upstream and one set downstream of the boat’s location. This method is most useful in river estuaries and bays with constricted entrances where there are high current speeds and frequent direction changes. It is also useful in crowded anchorages subject to current in order to prevent boats from wandering into each other.
Setting a Bahamian moor:
1) Set anchor 1 and back down on it at 3:1 scope to make sure it is secure.
2) Feed out twice the anchor rode that you require and drop anchor 2. For example, if you wish to be on 5:1 scope, then feed out 10:1.
3) Winch in the first anchor while paying out line for the second anchor until the boat is halfway between the two anchor locations. Tighten in on the anchor 2 rode to help it set by making a loop in the rode and putting it on a winch. Once set, take the loop off the winch and loosen the line.
4) When the current switches, the boat will be tethered by anchor 2. It might require some snugging of the now loose anchor 1 rode. Setting the rudder hard over to one side will influence the direction in which the boat turns on the current switch. Turning the rudder hard to the other side after each current switch will help prevent the two anchor rodes from twisting together.
Single anchor in wind and current: In areas that are subject to high wind and current, it is sometimes best to be on a single anchor, as boats tend to “dance” in such conditions. As with the Bahamian moor, it is advantageous to turn the rudder hard to one side. As the boat moves forward it will turn sharply to the direction indicated by the rudder and the forces imputing its motion will dissipate. It can be considered akin to heaving-to. Switching the direction of the rudder after each current shift will help avoid a snag on underwater obstructions.
Anchoring in strong wind
Scope and catenary are the first lines of defense in a strong blow. They work to absorb shock and reduce the angle of pull on the anchor.
Catenary: This is the curve in the rode caused by gravity. The more weight there is in the rode, the more catenary there will be at higher wind speeds. It is for this reason that many advocate for all-chain rodes. The catenary has two effects; it reduces the angle of pull on the anchor and absorbs shock from large waves hitting the bow.
Kellet: Catenary can be increased by adding weight to the rode. A simple but effective method of adding weight is using a kellet. A kellet is a weight, usually 10 or more pounds, that is tied or clipped to the anchor rode. The closer to the anchor that the kellet is attached, the better the effect on catenary. However, there should be a minimum distance of the depth of the water at high tide between the kellet and anchor to make sure you’re not trying to raise both at the same time.
Scope: When the wind is strong enough that the anchor rode no longer has any sag in it (i.e., it has lost all catenary), then it is very important to have adequate scope out. The more scope you have, the more the angle of pull on the anchor is reduced, making the anchor want to dig further into the seafloor rather than pop out.
While catenary and scope are important, sometimes more security is required. In these cases, it may be a good idea to deploy a second anchor. There are two main ways to set up two bow anchors: offset and inline.
Double bow offset: In ground with good holding, the most effective configuration is two bow anchors offset. The offset should be less than 45 degrees, as the function of the anchor will be reduced by side pull if the angle is greater.
How to set offset double bow anchors:
1) Set anchor 1.
2) Back down on the anchor to ensure it is secure.
3) Motor up to and over from the anchor 1 location and deploy anchor 2.
4) Back down on anchor 2 to ensure it is secure.
5) Pay out scope on both anchors until desired scope length is reached.
An alternative method is to use the dinghy to deploy anchor 2, similar to the stern anchor.
Double bow inline: Another method for setting double bow anchors is to deploy them inline. This is easier to set up, provided it is done correctly. It can be especially effective in anchorages with foul ground as anchor 2 clears a path for anchor 1 to set, though this requires some dragging to accomplish. The disadvantage of this method is that anchor 2 creates a furrow if dragging and it is harder for anchor 1 to set.
How to set inline double bow anchors:
1) Set anchor 1 (attached to the head of anchor 2).
2) Pay out a little more rode than the depth of the water at high tide and deploy anchor 2. Failure to put out enough rode between anchors will mean hauling in both anchors at the same time, which in a strong wind can strain a windlass.
3) Back down on anchor 2 and pay out rode to the desired scope. In strong wind, the more scope you have the better, as it will reduce the angle of pull on the anchor.
Urquhart at the anchor windlass.
Anchoring can be a stressful experience in non-ideal conditions, but with few techniques you can rest safe and secure and avoid many of the pitfalls into which we have fallen. Through practice, we have adapted and refined the above techniques to suit our boat and style and it is important to find the right mix for your boat.
Robin Urquhart is currently sailing through the Pacific with his wife, Fiona, aboard their 1979 Dufour 35 Monark. See more of his writing at www.youngandsalty.com, a website aimed at building sailing culture among younger generations.