Anchor chain size advantages

[Safari38LH]

I have a 38 footer that weights 22500. We currently have a 35lb CQR and 40 feet of 3/8 G4 chain plus rope (came with boat). We have cruised extensively the Canadian Maritimes, Bay of Funday, and Maine and have never dragged or had a problem with the anchor. We are currently outfitting for a year in the Bahamas and later the Caribbean. I have settled on a Vulcan 44lbs as our new bow anchor and am going to an all chain rode of 200 ft. (Spades are too exspensive and I don't like the single bolt holding it together. I also like the larger surface area of the Vulcan.) I was planning on staying with 3/8 G4 chain but the chain recommended for the 44lbs Vulcan is 5/16 G4. I like the idea of less weight and less cost but am wondering what I am giving up by going to a size smaller chain - 3/8 to 5/16. Any ideas? TIA

[a64pilot]

Your giving up a lot of weight.
Some will say that weight in the rode is beneficial which is true, just I believe in putting the weight in the anchor.
I am same weight and size and use 5/16 G43 chain, likely when it comes time to replace it, I will go with G70.
You may look at buying a half barrel of chain, it may be that you get more chain for less per foot that way as opposed to buying a set length.

[roverhi]

Your 35# CQR is woefully undersized for your boat, 45# is marginal for 25,000, A 55# would be more appropriate for 25,000# displacement. 5/16" chain is also pushing the strength necessary for a boat of your displacement. G70 will mitigate the strength issue but I'd like more weight in the chain for catenary when the wind kicks up. In the Bahamas anchorages will be shallow so you'l need a snubber to get elasticity in the rode.

We did fine including a tropical storm with 50 mph winds using 3/8" chain and a 45# CQR on a 20,000# boat.

[Stu Jackson]

Size the SYSTEM, not the bits & pieces and not just the vendor's tables

Anchor System Sizing Tables (Reply #6) & Why Swivels are a bad idea Ground Tackle & Anchor System Sizing TABLES & Swivels

Only YOU know what criteria you are using.

[DDabs]

My boat is 40 ft., ~25000 lbs., and the recommended chain from the builder was 5/16. I used to have that and a 35 lb. claw, upgraded to 3/8 with a 65 lb. Mantus and couldn't be happier.

[a64pilot]

I have asked a few times if people have stretched chain to the point of it being unusable and didn't get any replies, same for if anyone has broken chain.
I believe in most cases the attachment point at the boat is weaker than 5/16 chain.
Still I would prefer G70, but think my G43 is adequate

[thinwater]

Originally Posted by a64pilot

I have asked a few times if people have stretched chain to the point of it being unusable and didn't get any replies, same for if anyone has broken chain.
I believe in most cases the attachment point at the boat is weaker than 5/16 chain.
Still I would prefer G70, but think my G43 is adequate

From everything I can determine (I've done a good bit of load cell testing for articles) the ONLY way you are going to test the strength is if you get yourself in shallow water. At that point, if you are hitting the anchor with WLL bangs (over 2 tons) every few seconds and the anchor is going to drag and you are going to ruin the bow roller. Thus, avoid the problem:

1. Avoid shallow water if it is open to long fetch. If you are in impact zone it will not end well.
2. Use a LONG snubber, at least the length of the boat. 200 feet of any chain you are willing to carry is not going to give enough catenary to matter when the wind gets over 30 knots. I've done the testing, it gets bar straight an stops working as a shock absorber just when you are starting to need it, no matter what folks say. In deeper water, with more chain, the rules are different, but not with what you are taking about. I have a cat, and like you, I anchored on chain/rope for many years. One day I got a new anchor (Manson Supreme--works well) and all chain. The first night out I still had my old polyester bridle (with rope it was just for centering) and when the wind came up, "bang, bang, bang...." I immediately set to splicing up a 30' nylon bridle from a spare warp. It took all the sting out.

As for G70, make certain you have match connectors. Most chandleries will sell you the chain but don't have the connectors. Comical, or pitiful, depending on how you look at it (they will sell you G70 chain and a shackle only 1/2 as strong).

---

To me, your anchor and chain selection sound fine. Carry a back-up on rope and make a long snubber.

[Safari38LH]

Originally Posted by Stu Jackson

Size the SYSTEM, not the bits & pieces and not just the vendor's tables

Anchor System Sizing Tables (Reply #6) & Why Swivels are a bad idea Ground Tackle & Anchor System Sizing TABLES & Swivels

Only YOU know what criteria you are using.

Thanks Stu, based on your tables the chain should be good to about 50 kts. The 44 lbs Vulcan sizing is also based on 50 kts, with surge and poor holding.

I believe this is based on working load not breaking load.. does that mean I have huge safety factor as the breaking limit is 11700 lbs for 5/16 . Or I don't really understand the difference between WLL and MBL.

I feel comfortable with 50 knots. I am a careful at anchoring and as I said I have never dragged with a 35 lb CQR - the Vulcan is a much more powerful anchor.

[Orion Jim]

I have a 12,000 pound displacement 31 footer with a 35# Spade and 5/16 BBB. I sleep very well.

[Suijin]

I'm 40' and probably 25k fully loaded, and my 5/16 chain has been through a few serious storms with a 45 lb. CQR. Added a 44 lb. Ronca, which holds better than the CQR for sure. I can't see any reason to move up to 3/8 chain as I'm pretty if it ever fails it will be due to a flaw, not it's inherent load capacity.

I took my swivel off when I switched to the Rocna because it's only advantage was letting me spin the CQR around when I was cleaning it before bringing it aboard.

[Herreshoff]

I'm of the school of thought that chain weight is of more importance than anchor weight (though obviously both are essential). The way it was explained to me that made the most sense was this.
Imagine two people take opposite ends of a 20 metre piece of rope and walk away from each other. With effort they will be able to get it fairly tight, but not completely. If we now replace the rope with chain we can see it would be very difficult, and more difficult the heavier the chain gets. This is what I feel is happening at anchor most of the time. As your boat moves backward it's trying to stretch that chain from a curve into a straight line from the anchor to the bow. I would think most of the time it would never get tight enough to actually put much of a load on the anchor itself. Its only been in really heavy blows, or when I don't have enough scope out, that I feel the chain completely tighten. It's at that point I feel the anchor is doing most of its work. If this way of viewing it is accurate then chain weight would seem to be of the upmost importance.
I might be completely wrong but that the way I see it.

I would suggest keeping the heavier chain.


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[brianlara 3]

What Herreshoff said.
At 24' X 9' beam and a total weight of 6,700lbs I probably live on the smallest (at anchor 24x7) boat on CF. Been on board for 7 years
FWIW. My (bow) ground tackle consists of:
a. Muir Easy Weigh 1100 watt horizontal windlass.
b. 250 ft G40 5/16" chain.
c. 35lb Manson supreme.
d. 480Ah AGM (4X120).
e. Rocker switch in the cockpit.
f. 2 X 100ft nylon snubbers which I can crank from the P&S sheet winches.
never, ever again...will I have an anchor swivel.

Stern gear: 25lb Manson Supreme, 26ft 3/8 short link, 30 meter rode.

Just depends on how badly you don't want to get out of bed for ANYTHING.
Cheers. BRIAN

[Elie]

Originally Posted by a64pilot

Your giving up a lot of weight.
Some will say that weight in the rode is beneficial which is true, just I believe in putting the weight in the anchor.
I am same weight and size and use 5/16 G43 chain, likely when it comes time to replace it, I will go with G70.
You may look at buying a half barrel of chain, it may be that you get more chain for less per foot that way as opposed to buying a set length.

I have a different opinion on this matter. One of the main function of a chain is to help the anchor to set kwicly and provide a significant damping effect during gust of wind a therefore reduce the violent chocks on the anchor.
My chain is 12 mm G4, and i would'not replace it by a lesser chain. Mt boat is 12,5 tons 47 ft sloop and I find my chain well suited for the job, of making me sleep well.
We shall keep in mind also that chain has a much less working load capacity than an adequate nylon rode.

[wrwakefield]

Originally Posted by Safari38LH

I have a 38 footer that weights 22500. We currently have a 35lb CQR and 40 feet of 3/8 G4 chain plus rope (came with boat). We have cruised extensively the Canadian Maritimes, Bay of Funday, and Maine and have never dragged or had a problem with the anchor. We are currently outfitting for a year in the Bahamas and later the Caribbean. I have settled on a Vulcan 44lbs as our new bow anchor and am going to an all chain rode of 200 ft. (Spades are too exspensive and I don't like the single bolt holding it together. I also like the larger surface area of the Vulcan.) I was planning on staying with 3/8 G4 chain but the chain recommended for the 44lbs Vulcan is 5/16 G4. I like the idea of less weight and less cost but am wondering what I am giving up by going to a size smaller chain - 3/8 to 5/16. Any ideas? TIA

Safari,

I went through the same chain exercise a couple of years ago when faced with replacing our windlass.

We are cruising higher latitudes these past 20 years and therefore 'deep' anchorages are the norm [and our preference... e.g., 50-90 ft.] This means we typically can get away with less scope than in shallow anchorages [e.g., 4:1 is storm scope vs. 5 or 7:1 in shallower water] and the catenary curve is totally different from the shallow water curve.

Since our main bower is tested at holding 5000 lbs in sticky mud, and I wanted to carry as much chain approaching that WWL on the primary and secondary anchors as would fit in the locker. I went with 5/16" G4 on our 44k lb cruising weight 43 footer. With Crosby forged shackles, everything in the ground tackle has the same working load capacity.

I have investigated upgrading to 5/16" G70 chain in the future, but that would require oversized links on the ends so appropriately sized forged shackles could be used. A couple of chain manufacturers will add those links, but they won't heat treat them, so they remain at G4 strength... A conundrum that so far negates the benefit of the 5/16" G70 chain for me. [This issue may resolve itself with larger G70 sizes, but I don't want larger chain...]

While on the topic of G4 vs. G70, it is worth noting the WWL safety factor is only 3:1 for G4 and 4:1 for G70. [i.e., WWL is calculated at 1/3rd of breaking strength for G4 and 1/4th for G70 meaning G70 is even stronger than first glance might assume...]

If you are interested in more details about our arrangements, here is our ground tackle inventory which has lots of details, links, and an external resource section.

Best wishes deciding what is best for you.

Cheers! Bill

[Cheechako]

I used 3/8 G4 on my 33k lb boat. I imagine 5/16 will be fine. Never hurts to have a bit on the more robust side though. Have you calculated how much more weight the 3/8 is?