Setting Two Anchors

[barnakiel]

We use 2 anchors as a rule, except:

- if/when we have to swing in synch (tight anchorage, many boats),
- if not leaving the boat and the weather is fine (some night-overs),
- when there is plenty of open water behind the boat (e.g. many Carib anchorages),
- when the bottom is known to be excellent holding and we are on all chain rode.

Given the number of exceptions one might think that we never use the second anchor. Yet, time-wise, I think we used the 2nd hook about 50% of all anchor time.

b.

[outdoor]

in all these discussions on using 2 anchors or not, nobody seems to discuss the benefit of using a second anchor on the same rode. Would it not improve the first anchors holding power by almost double (similar to Kiwi Anchor Rider) since it should keep the anchor rode horizontal?

As well would it not reduce your swing?

i recently was anchoring in an area that to me was crowded and i like to put out the minimum 5:1 but with that to me it would allow too much swing. Some boats near me must have been using some different setup since their rode seemed to go straight down almost into the water, yet mine was pulling out front more.

[AquatiCat]

It is simpler! And if your dink doesn't mind, why should the neighbors :-)

[craigsmith]

Originally Posted by outdoor

in all these discussions on using 2 anchors or not, nobody seems to discuss the benefit of using a second anchor on the same rode. Would it not improve the first anchors holding power by almost double (similar to Kiwi Anchor Rider) since it should keep the anchor rode horizontal?

It was discussed in posts 5, 6, 19, 20, and 21 of this very thread.

[Condor-cnd]

Originally Posted by Eleebana

Rocna advises having the secondary anchor forward of the main anchor. So the seconadry hits the dirt first, don't set it but keep paying out chain until the primary anchor hits dirt and then set it.
Greg

we dont have a rocna; but we do have a second anchor. The problem is that we have a small main anchor with a light chain. The second anchor is smaller, but has a short heavy chain.

My idea is to drop the first anchor 20 foot, then attach the short chain from the second anchor to the main anchor chain.

The advantages of this should be 1] to keep the main chain down on the sea bed. and 2] to save having to use a weight (5 litre water bottle full of wet sand) to keep the chain down. 3] the second anchor should add some bite.

Yesterday we tried anchoring with 2 anchors at 45 degrees in the bay of Espalmador in Formentera. We dragged horribly and eventually had to up anchor and go down the coast the bay of Sabina, which incidentally is less congested ... which meant that we could let out all the chain, that seems to have solved the problem for the moment.

[craigsmith]

Condor, have you read any of the above?
Your problem is as you said from the start, your main anchor is "small". You fix this by making it bigger. Anything else and you will continue to have problems. Doing what you suggest is not a good idea in any respect.

[Randyonr3]

along with our anchor, one size larger than what is recomended, we've added a series of weights that we use if the weather gets rough..
The weights, at about 20 lbs each, are attached to the chain about every 30 feet.. they simply attach to the chain with a shackle.
with a 25 Rocna and a dozen of the lead weights, we've never had a problem with moving around in a storm,

we do use a second and anchor at times but only off the rear......

[nautical62]

On my last 3-month Bahamas cruise, I only deployed 2 anchors on one occasion, and that was the second off the stern to keep me head into the waves on one particularly rolly occasion.

I used to use to use the 180 degree bahamian anchoring system fairly frequently, but have mostly abandoned that in favor of setting one anchor well and just ensuring I anchor where I have room to swing with the tidal changes.

[Rou-Coo]

For these late posters read the link referred to in post #21! It carefully reviews the fallacy of weights or second anchors set part way down the rode.

[Randyonr3]

Originally Posted by Rou-Coo

For these late posters read the link referred to in post #21! It carefully reviews the fallacy of weights or second anchors set part way down the rode.

You are incorrect...... the post refers to added anchors and NOT to weights added to the chain....

[craigsmith]

It does in one section, but the article on just kellets is here where the topic is covered thoroughly:
Kellets or Anchor Angels / Sentinels: Uses and Applications

[Rou-Coo]

Originally Posted by Randyonr3

You are incorrect...... the post refers to added anchors and NOT to weights added to the chain....

In the article I referenced, the use of kellets (anchor rode weights) is described as follows:

Don’t bother with kellets (AKA anchor angels or buddies)

Kellets are supposed to increase the holding capacity of an anchor system by holding the rode low and hence keeping the angle of pull on the anchor closer to the ideal of parallel to the seabed. In practice, their effect even when deployed in an optimal point on rode (close to the anchor) is very minimal and the high loads which must be expected on a tandem rig will straighten the rode very quickly. They have negligible effect on ultimate anchor performance in a regular anchoring set-up, and even less when tandems are deployed. For more on kellets, study the article “Anchor Rode Kellets”.

The article on Kellets is the one also mentioned by Craig Smith just above this.

It is also addressed in the first article mentioned where it says: "study the article on caternary and scope in anchor rode":

Catenary & Scope In Anchor Rode: Anchor Systems For Small Boats

In 'Caternary and Scope in Anchor Rode' it is says:

The most important conclusion emphasizes the importance of scope. If the graphs above are studied, it is obvious that the benefit of catenary is mostly lost in strong winds, with the exception of very deep water, and since the anchor is probably quite capable of holding given an adequate angle of pull, the sole remaining thing you can do to help the anchor is veer more rode.
If you want to increase the potential holding power of your system for the same scope, then the answer is to put the focus back on the anchor. If you have adequate scope deployed yet your anchor tends to drag, consider upgrading to a superior modern design. At the same time you could also increase the size of the anchor. Taking a few kilograms of weight out of the chain and putting it into the anchor results in a significant increase in holding power.


So, before you say that I'm 'wrong' read the material and make sure you understand it. I may well be wrong but I at least like to have that pointed out in a way that I can actually learn something from it.

[thinwater]

Condor:

To further explain, setting 2 anchors at 45 deg does not add any holding; eventually the wind shift a bit and all of the strain comes on the weaker anchor, it drags, and often they both foul. In fact, simple trig will show that the wind only has to shift about 15 deg for 100% of the strain to be on one anchor. If the angle is greater than 45deg, this problem is worse.

I'm also less than convinsed that tandem anchoring will help much; there are simply too many ways for the second anchor to interfere with the primary in a shift. My personal expereince, rock climbing expereince, and my engineering "sense" suggest that a wind shift, even slight, is generally at the root of a failure... unless the anchor never set at all.

I do use 2 anchors with some frequency, but it is NOT to compensate for having small anchors.

• I often anchor in small creeks with no room to swing. The water is shallow, and I have a very fast system for setting the 2nd (it is on its own 40 rode--I lower it off the stern and connect the rodes near the bow--no tangles and no fiddling). Generally I am well out of the wind and holding is a secondary concern.
• I anchor in some areas where the bottom is extremely variable (patch of sand, then a patch of grass or hard-pan so tough a screw driver won't go in). If I expect a thunderstorm, I don't want my anchors to have to re-set, because there is little margin for doing so. If I had a big Rocna, perhaps I would not feel this is required, but it is a habit in a few places I know to be very bad. In some of these, the anchor must be hand placed. Yes, anchoring elsewhere would make sense, but I like the spots very much, so there.

However, either anchor can easily hold in 60 knots and has done so. I can see no engineering reason how a second anchor will reliably improve holding in any more general case. The "hammer lock" idea (a small anchor on very short scope, not intended to hold but just to reducing yawing) is interesting, but I've never had a boat that horsed around at anchor, so I have no experince.

Now that windlasses are common, light anchors have limitied use, IMHO; the "lunch hook" is going to be what ever is on the windlass anyway, and that will be the big boy. I like a big Fortress to take in the tender to kedge off, but that's it.

Yes, Craig can come off as self-assured and high-handed, but I find the engineering information on his web site to be clear and well founded; I am an engineer and I can find no serious faults in his presentation, only small differences in opinion that no doubt come from differnces in sailing location and expereinces. He's a bit conservative in spots, though he also states as much. It is a great resource. My compliments.

[Randyonr3]

In the graph it shows a 33 lb weigh on a 6 to 1 scope if I'm reading it right,
In 30 feet of water, you have out roughly 180 feet of chain.. and the kellet is 30 feet from the anchor....
In my post I stated "in storm conditions" my scope would be at 7 to 1 or better, and the total weight of my Kellet would be 120 to 180 lbs with the same scope...
I would like to see a graph on the use of a kellet or weight effect as the weight is increased and along the length of the chain..
The weight of your Kellet is 33 lbs....... What is the effect when raised to over 150lbs

[speakeasy]

Originally Posted by Randyonr3

In the graph it shows a 33 lb weigh on a 6 to 1 scope if I'm reading it right,
In 30 feet of water, you have out roughly 180 feet of chain.. and the kellet is 30 feet from the anchor....
In my post I stated "in storm conditions" my scope would be at 7 to 1 or better, and the total weight of my Kellet would be 120 to 180 lbs with the same scope...
I would like to see a graph on the use of a kellet or weight effect as the weight is increased and along the length of the chain..
The weight of your Kellet is 33 lbs....... What is the effect when raised to over 150lbs

Good question. I'd be interested too. One other benefit to tandem anchoring, I have two 44# bruce, is that besides not fouling as a 45 degree double can, they can reset easier and quicker being inline should they drag. Is that assumption true?