Cruising Anchor Chain Length

[s/v Jedi]

The 99% of anchoring rule: one anchor only, all chain rode, snubber, 1:3 to 1:5 scope.

Smaller boats have smaller anchors that don’t hold so well and they can get away with a bit more scope and still don’t swing that wide around the anchor. Bigger boats have big anchors that hold extremely well so get away with short scope 1:3 so that their swing around the anchor stays tight

[Dockhead]

Originally Posted by Black Eagle

And that it's the reason (or one of the reasons) why in strong conditions you can't use only one anchor, but maybe two, or rope on shore or in the mangrovias, or both!
Because if it not possible have enoght rode your anchor doesn't work at its best.

Nobody can persuade me that in the case of the pictures of Noelex, that it is what I'm talking about, with more rode the anchor doesn't work much better!

IF you have on board, and can deploy, enough more chain, to keep the last link on the seabed, then of course the anchor holds "at its best", as you say.


But the best is the enemy of the good. First of all, as I said, in some conditions no feasible amount of chain will prevent the chain from going bar tight and lifting off the seabed. Read all the stuff on this written by Dashew and Peter Smith and others. I have 330kg of 12mm chain, 100 meters of it, and the last link starts lifting with my boat when the wind is in the low 30's, when I'm in say 12 meter deep water. This will happen much sooner with shorter and/or lighter chains.



So you cannot count having 4 or 5 meters of chain on the bottom!


If your anchor is of good design, it will have nearly its ultimate holding force on as little as 5:1 scope, even if you have no chain at all and are using rope rode. If the anchor is big enough, then in many cases 50% of the anchor's ultimate holding power will be more than enough even in a big storm, so in some cases you can get away with much less scope, even in a storm.



Scope is great when it's available, but if it's not, it's basic good seamanship to understand what you can get away with in terms of scope in different situations. I've been through gales on scope of about 2.5:1, and for a very good reason -- the only good holding was in water nearly 35m deep, and I only had 100m of chain and no room to swing to more than that even if I'd had it. If I had believed an erroneous formula like "if you can't have 4 or 5 meters of chain on the seabed, you can't anchor" -- I would be dead. Because then I would have been forced to anchor in poor holding or too near a lee shore, as the only alternative in that place (which was in the Arctic above 71N). As it was, I knew my anchor would hold, and it did.



Don't make a fetish out of scope -- it leads to errors. Scope is not the only parameter which determines whether your anchor will hold or not. A different and better way to look at it -- not, "if you can't put out enough chain so that several meters are always on the bottom, you can't anchor", but rather, you should say, "if your anchor won't hold in a storm on 2.5:1 in deep water and good bottom, you need a bigger and/or better anchor".



And I would never use two anchors at the same time, which is a poor substitute for a single larger one.

[cuffy]

I think a very good illustration of diminishing returns of scope is by one of our forum contributers
https://pbase.com/mainecruising/anchor_scope&page=2
Anything past 6 to 1 and it appears very little gain.

[Yellow bird]

Originally Posted by Dockhead

IF you have on board, and can deploy, enough more chain, to keep the last link on the seabed, then of course the anchor holds "at its best", as you say.


But the best is the enemy of the good. First of all, as I said, in some conditions no feasible amount of chain will prevent the chain from going bar tight and lifting off the seabed. Read all the stuff on this written by Dashew and Peter Smith and others. I have 330kg of 12mm chain, 100 meters of it, and the last link starts lifting with my boat when the wind is in the low 30's, when I'm in say 12 meter deep water. This will happen much sooner with shorter and/or lighter chains.



So you cannot count having 4 or 5 meters of chain on the bottom!


If your anchor is of good design, it will have nearly its ultimate holding force on as little as 5:1 scope, even if you have no chain at all and are using rope rode. If the anchor is big enough, then in many cases 50% of the anchor's ultimate holding power will be more than enough even in a big storm, so in some cases you can get away with much less scope, even in a storm.



Scope is great when it's available, but if it's not, it's basic good seamanship to understand what you can get away with in terms of scope in different situations. I've been through gales on scope of about 2.5:1, and for a very good reason -- the only good holding was in water nearly 35m deep, and I only had 100m of chain and no room to swing to more than that even if I'd had it. If I had believed an erroneous formula like "if you can't have 4 or 5 meters of chain on the seabed, you can't anchor" -- I would be dead. Because then I would have been forced to anchor in poor holding or too near a lee shore, as the only alternative in that place (which was in the Arctic above 71N). As it was, I knew my anchor would hold, and it did.



Don't make a fetish out of scope -- it leads to errors. Scope is not the only parameter which determines whether your anchor will hold or not. A different and better way to look at it -- not, "if you can't put out enough chain so that several meters are always on the bottom, you can't anchor", but rather, you should say, "if your anchor won't hold in a storm on 2.5:1 in deep water and good bottom, you need a bigger and/or better anchor".



And I would never use two anchors at the same time, which is a poor substitute for a single larger one.

Ok we sail in two different planet, no probs.

[Auspicious]

Originally Posted by Black Eagle

Ok we sail in two different planet, no probs.

I'm glad @Dockhead sails on the same planet as me.

[Yellow bird]

Originally Posted by Auspicious

I'm glad @Dockhead sails on the same planet as me.

I hope to meet you two at a pub and have a beer together,
at the same time I hope never meet you with your boats upwind my boat on an anchorage

[Marekaofholland]

I don't want to burn my fingers on the topic "what's best". Been sailing since my 20-ies (now 70) and had all kind of anchors. With that experience in mind we now have 100m of 12mm chain, a 35 kg Ultra. If needed 100m of 22mm rope on our 21 tons 49 OysterPH. We are behind anchor 95% of the time in all kinds of weather. how you lay your anchor depends on wind, waves, anchorage, bottom etc. I want to sleep at night so I am conservative....that's why I like oversized anchor, heavy chain and length....

[Dockhead]

Originally Posted by Black Eagle

Ok we sail in two different planet, no probs.

If the normal laws of physics don't work on your planet, then there's nothing to talk about. If they do, however, it would be interesting to know what specifically you disagree with in Post #152.

[TheOffice]

As we walked the boat show in Annapolis last weekend we were appalled at the size of the anchors on the bows of the production boats. I'm guessing the chain is almost non-existent too.

[a64pilot]

Originally Posted by TheOffice

As we walked the boat show in Annapolis last weekend we were appalled at the size of the anchors on the bows of the production boats. I'm guessing the chain is almost non-existent too.

Chain, windlasses and anchors are expensive, and many boats never use theirs, new boats tend to be in Marina’s, not anchored out.
List price for my Windlass is about $5,700, easy to save save $2,000 or $3,000 for a manufacturer by having a windlass not really big enough. Then add a couple of grand for good anchors, and then chain on top of that. With shipping and if you pay to have it installed, it’s not hard to put $10,000 into anchoring.
Then as now your anchoring and need a way to shore, it’s not too hard to put say $6,000 into a dinghy. Then davits, Solar etc. etc.
for most people they way they use their boats, staying in Marina’s is the cheaper way to go.
Most of the big 50+ powerboats in the Marina I’m in have tiny CQR’s or other plows, I mean maybe 20 kg anchors at most. They aren’t ever going to be used I don’t think.

[wingssail]

Originally Posted by tgradyv7m

It just really comes down to how well will you sleep if you have anchor with 35 knots of wind in the forecast (or 40, or 50)? 100m and 30 m min rode. As big of chain as your boat can handle. Me'z think

Sorry, I don't want to be sleeping like a baby in that situation, I want to be awake or just napping. The argument that if I add enough ground tackle I can sleep through a storm is not persuasive.

[model 10]

Originally Posted by Dockhead

If the normal laws of physics don't work on your planet, then there's nothing to talk about. If they do, however, it would be interesting to know what specifically you disagree with in Post #152.

I can think of a couple. You make it sound like all bottoms are the same. I can think of some that if you don't have some sort of a plow, you will drag in 25+. It really doesn't matter how big your new gen anchor with a roll bar is. With others, the bottom is so hard, nothing will dig in and you use all the chain you have to help out. When anchoring near a reef it only makes sense to use a second anchor sometimes to handle wind shifts during the night. Again, it does not matter how big your anchor is. Thes short scopes I'm hearing about don't belong in any cruising we have done. It's not just me. We are anchoring just like everybody else I see and nobody anchors with just 3 or 4:1. That would be crazy unless you were in thick mud or it was deep.

[s/v Jedi]

Ignorance is bliss

I don’t know much about other anchors but the Bruce I know pretty good. Even when the rode goes up from the anchor at a 30 degree angle, the anchor will bury successfully. It is absolutely designed to be used at a 1:3 scope.

Here is some info:

The superiority of the Bruce's shape gives it tremendous efficiency, particularly on short scope over a variety of bottom conditions.

Based upon field testing and engineering studies, Lloyds of London approved the replacement of a 45,000 pound conventional oil rig anchor with a 14,331 pound Bruce. The Bruce has earned an Award of Special Merit for Engineering Products Award from the Design Council (London, 1978).

Constructed of a single piece of cast steel, each Bruce Anchor has no movable parts nor any flimsy components. This allows each to be covered by a lifetime warranty against breakage.

Absolute Roll Stability

Every anchor has an upright orientation at which maximum holding power is achieved. Changes in wind or tide cause the angle of pull to change and to roll the anchor onto its side. A good anchor resets itself quickly to achieve upright orientation.

The Bruce Anchor rolls upright. irrespective of initial drop attitude, within 2 shank lengths after engaging the sea bed and, at a rode-angle of up to 30 degrees (ultra short scope), begins burial.

Full Veering Capability

The curved wingtips and point are configured so that pull on the rode automatically rolls the Bruce to its optimum upright orientation, whether for initial setting or resetting.

This capability is important in minimizing dragging when wind or tide change. Instead of breaking out, the Bruce can remain embedded as it veers. The Bruce banks in the sea bed and maintains high holding power, even through 360 degrees.

Short-Scope Holding Power

The Bruce Anchor will bury in the sea bed at rode-angles up to 30 degrees (at the anchor shackle) where most other anchors require 10-15 degrees. In crowded anchorages or in deep water, this distinction means more than a peaceful night" it can become a yacht or life-saver.

The reason for the Bruce's better performance with short scope as its design: the center of fluke area is located much closer to the forward end of the fluke than is possible in other anchor designs.

Among Rocks and Coral

The Bruce works well in bottom conditions where many anchors are ill-suited. Among the worst conditions are rocks and coral. Here, the Bruce Anchor's three strong points let this anchor grab as easily as the Fisherman type.

And because there are no flimsy or moving parts, there's less risk of bending or jamming. In fact, the one-piece construction in heat-treated cast steel gives the Bruce greater strength than any other patented anchor of similar weight.

Easy to Recover and Stow

Despite the superior burying and holding power, the Bruce is easily broken out for hauling. The short, broad single fluke gives rise to small shear moments in the sea bed when the anchor is rotated upward during hauling.

The Bruce is very compact. Because of its inherent roll stability, it required no stock and thus is narrower. It has no moving parts to secure, and stows easily and conventionally in a bow roller system.

[Breaking Waves]

Originally Posted by s/v Jedi

Bruce

Here is some info:

J,

I also like the Bruce. Have also used it alot at 3:1 scope. Did some anchor testing and it did better at short scope than the 'usual next-gen suspects'

I dont know where you got your copied text - but just be aware that the commercial-sized Bruces are often a somewhat different shape than the recreational size ones. I would be careful about assuming comments/tests on the one carry to the other.

Here is a pic I just copied off the Bruce 'products' page -

[wingssail]

Originally Posted by CAVOK

Is there any consensus about what is the ideal anchor chain length to carry on a cruising yacht. We intend to cruise the Med then over to the Caribbean and possibly further, so there isn’t any specific cruising area. I intend to have only chain as I will be anchoring out as much as possible. Ideally the more the better, but cost, weight and it’s distribution also have some bearing. Thought there might be some long-term cruisers that may have an opinion based on experience.

Originally Posted by s/v Jedi

So many anchoring posts (I’ve done hundreds here) and still so many that didn’t get it right. Possibly they simply disagree. Your view is only one more opinion, not necessarily "right".Here is mine, just as valid as yours:

1. Determine the biggest anchor that fits on your roller, then try one that is one size up from there.No, size your anchor properly, and that does not mean whatever humungous anchor that will fit, then one size bigger. There are more things to consider on a sailboat than anchoring weight. Many people, and I as one of them, don't want more weight on the bow than is needed. Use any one of many charts for sizing your anchor. Then go up one size if you want to. This is where putting money in makes more sense than a more expensive insurance policy.

I've looked at the force applied to an anchor system in various wind strengths, including dynamic loads, FOR MY BOAT'S AREA AND WEIGHT, and I see no reason to go to a anchor much bigger than recommended by the manufacturers. My 44lb Bruce, not one of the top anchors based on holding power, still has more holding power than I normally can expect to need and my 66lb has vastly more than that. Using Alain Fraysse's calculators I'm good to more wind with my 44lb than I have ever experienced, (not considering the dynamic load, which I just have not seen much evidence of). Cruisers should take into account their actual frontal area of their boat and rig, add to it for yaw, and especially the dead weight which contributes so much to the dynamic load. If you have a light boat with less top hamper, your anchoring loads are much less. If your boat is light in the ends, does not pitch and plunge on every wave or swell that passes through, you'll experience much less shock loading and dynamic loads on your anchor. Size to your needs, not your you fears.

2. Get a strong, vertical windlass with enough room underneath for a high, narrow chain locker. If that needs to go further aft to get enough height, go further aft. Mine is 14’ aft of the bow.I agree with this advice. My windlass, 10' back from the roller, gets weight off the bow and provides more room for chain to drop. Most boats however do not have the luxury to reconfigure their interior and anchor locker. (They could however, buy a 64' boat). But look at options to make more room for the chain to drop. This Is VERY helpful when trying to retrieve an anchor in a hurry.

3. Between windlass and roller, create a strong point and mount a chain stopper like the one from Maxwell.Alternately run a strong line with a chain hook on it from a strong point farther aft.

4. Get at least G4 chain. If you can’t fit 400’ / 120m of that in the chain locker then go down one size and up to G7 grade. Get the shackle to match that grade, they do exist, or order the chain with enlarged end links at both ends (so that you can turn it over end for end to extend lifespan.G40 is fine, put as much on as will fit properly below the windlass. I carry 275' even though twice that will fit. I, again, am sensitive to weight, but less chain limits your ability to anchor in deep areas, such as South Pacific, high latitude, and some other cruising grounds, so get a lot of it but be cognizant of the impact that much weight will have on your size boat. I move my chain aft to a locker by the mast, and can carry more weight there without causing excess pitching.

5. Get 400’ / 120m of chain, no rope at all. For many people, 400' is excessive. I'd say that 300' is probably sufficient. If you can fit 400' of chain, part of it off the bow, and still get a good drop in the locker for than chain, fine.What I tie to the inboard end is small diameter, floating polypropylene rope to function as a marker in case the whole sjebeng goes overboard... intentionally or not.

6. Get a spare anchor, same size as the primary. Upsize your spare anchor. You'll need to carry it elsewhere than your bow, somewhere below, properly secured. You won't need it often but if a big storm is coming, or even in expected normal conditions become exceptionally bad, you can deploy it. This may never happen to you, but carrying too much weight on the bow will affect you every day 360 days a year.Consider the Mantus that can be disassembled for easy storage. You will use this when the primary anchor is lost, or in very rare cases like cat 4-5 hurricanes without even mangroves around to hide in. If you already have a Mantus then this is the excuse to buy the new model

7. Get a second (kedge) anchor. Consider a light weight Fortress that is easier to handle with the dinghy. OKThis will be used when anchoring on waters with tidal flow and little room, like rivers, or as a stern anchor on the beach when there is no palm tree, or when hiding in mangroves etc.

8. Get a second rode, consisting of 20’ of chain, spliced to 300’ of nylon.YES This will normally be used with the second anchor, unless the primary rode is lost.

9. Search this forum for the Jedi 99% anchoring rule

Some other comments (other than Jedi's):

There is no reason for a snubber to fail in Cat 1,2, or 3 winds if it is of the proper size and, most importantly, has proper chafe protection.

That’s it, no more worries. The snubber will work 100% but not break unless it is worn out. Checking for chafe etc. and replace in time. Don’t bother with chafing gear, the snubber itself is the chafing gear, the disposable component of the system. You need to replace it periodically anyway, before it has become stiff and lost it’s stretch. Without stretch it doesn’t work. Too large a diameter or too old and it’s a fail. Get it right

This is not correct. Nylon, under high loading, will heat up and chafe more easily, even inside of chafe gear. I've seen chafe gear melted by the heating of the snubber right at the bow roller, in a very short time.

I have used a non-stretchy piece of line, such as dyneema or even polyester, inside the anti chafe gear, and placed the nylon outboard of that, so that the nylon does not touch any part of the bow, including the roller, and this reduces chafe in high load conditions about 100% Still, this may not be the end of your worries. It is essential to check the anchor, rode and snubbers frequently in high load situations, and to have spare snubbers. Be sure to fix the anti-chafe gear to the snubber so it won't creep away from where it's needed.