BBB Anchor Chain: Is it the Best Choice for Cruising Boats?

BBB anchor chain - or 3B as it's also known - is certainly a good choice of anchor chain because it's calibrated for use with most modern anchor windlass gypsies (aka 'wildcats'). It may be the most commonly used anchor chain on cruising boats, but it's not the only choice...

Whatever chain you choose, don't forget to mark it at regular intervals...

It's heavy stuff, anchor chain, which is exactly what you want when it's holding your anchor firmly on the seabed - but exactly what you don't want when it's stowed in its locker in the bow of the boat.

Here it will increase the boats tendency to pitch, affecting both crew comfort and boat performance - particularly so for today's lighter displacement cruising boats.

Fortunately you don't have to trade strength for weight. Some types of anchor chain are both stronger and lighter than others.

Let's take a look at the three basic types - Proof Coil, BBB and High-Test anchor chain...

Proof Coil Anchor Chain

All welded steel chain is categorized into one of several grades.

Proof Coil is Grade 30, indicating that it's manufactured from low carbon steel - the lowest grade for anchor chain.

Proof Coil chain is not calibrated, and is therefore unsuitable for use with anchor windlasses.

However, it's perfectly suitable for rope/chain anchor rodes for small boats - providing you're happy to haul it in by hand.

sketch showing anchor chain link dimensions

Size

1/4"

5/16"

3/8"

1/2"

L

1.02"

1.15"

1.45"

1.56"

W

0.50"

0.49"

0.60"

0.81"

t

0.275"

0.330"

0.397"

0.520"

BBB Anchor Chain

Like Proof Coil, BBB anchor chain is manufactured from low carbon steel, but there are two differences that make it more suitable for use as anchor chain:~

BBB chain is calibrated for use on anchor windlasses;

BBB chain has shorter links than Proof Coil chain.

It will usually have been hot dip galvanised during the manufacturing process to improve its resistance to corrosion, although electro zinc plating is sometimes offered as an alternative.

It's marginally stronger than Proof Coil due to its slightly greater thickness.

Size

1/4"

5/16"

3/8"

1/2"

L

0.87"

1.00"

1.09"

1.34"

W

0.43"

0.50"

0.62"

0.75"

t

0.281"

0.343"

0.406"

0.531"

High-Test Anchor Chain

High-Test Anchor Chain is much stronger than BBB chain, and is also slightly lighter.

It achieves this through the use of a higher grade steel with increased carbon and manganese content.

High-Test Anchor Chain is produced in 3 grades:~

Grade 40
Grade 43
Grade 70

Grade 40 has been widely replaced by Grade 43, the sole difference between the two being the shorter links of the Grade 43, which makes it more flexible and ideal for use with anchor windlasses.

Size

1/4"

5/16"

3/8"

1/2"

L

1.02"

1.15"

1.30"

1.56"

W

0.50"

0.49"

0.60"

0.81"

t

0.274"

0.330"

0.397"

0.520"

Grade 70 Anchor Chain is 20% stronger than Grade 43 chain.

It's manufactured from the same steel as grades 40 and 43, but is then heat treated which gives it its increased strength.

It's the strongest, weight for weight, of all anchor chains.

However, there is a risk that re-galvanising it will put it through a further heat cycle which could weaken it.

But re-galvanising any chain isn't always successful and is seldom cost effective.

Size

1/4"

5/16"

3/8"

1/2"

L

1.24"

1.12"

1.30"

1.56"

W

0.46"

0.48"

0.60"

0.81"

t

0.274"

0.334"

0.392"

0.510"

Fascinating stuff, but what does it all mean?

The meat of this article is set out in the table below, which shows the weight and strength of the three main types of anchor chain currently in use.

Let's say we've got a 40ft ocean cruising boat with 200ft of worn-out 3/8" BBB anchor chain in the chain locker. What do we replace it with?

We could simply replace it with similar chain, or

Replace it with 200ft of High-Test Grade 43 or Grade 70 chain of the same size, benefiting from the increased strength and resistance to abrasion of the High Test anchor chain, or

Replace it with the same length of High-Test Grade 43 or Grade 70 chain of a reduced sized, whilst maintaining the strength of the chain whilst minimising the weight of the chain stowed in the chain locker, or

Replace it with an increased length of High-Test Grade 43 or Grade 70 chain of a reduced sized, without increasing the total weight of the chain stowed in the anchor locker.

Chain size:

BBB

Wt/100ft:

SWL:

Grade 43

Wt/100ft:

SWL:

Grade 70

Wt/100ft:

SWL:

1/4"

72 lbs

1,325 lbs

69 lbs

2,600 lbs

74 lbs

3,150 lbs

5/16"

113 lbs

1,950 lbs

100 lbs

3,900 lbs

103 lbs

4,700 lbs

3/8"

165 lbs

2,750 lbs

145 lbs

5,400 lbs

145 lbs

6,600 lbs

1/2"

272 lbs

4,750 lbs

234 lbs

9,200 lbs

264 lbs

11,300 lbs

So is BBB Anchor Chain the Best Choice?

Looking at the table above you might be persuaded by the increased strength of high-test grade 43 and grade 70 anchor chains to decrease the weight of the chain stowed in your anchor locker, or alternatively carry more of it - both without sacrificing strength. (see points 3 and 4 above)

In either of these two scenarios, BBB isn't the best choice - Grade 43 or 70 is.

But when at anchor, the weight of chain suspended in catenary contributes significantly to overall security, which would seem to give BBB anchor chain the edge over its stronger, but lighter, cousins. So unless you want to go up at least one size in one of the High-Test grades to maintain the weight, from this viewpoint BBB anchor chain is the best choice.

Well I didn't say there was going to be a simple answer!

And I haven't mentioned cost - you can guess in which direction that goes...

Stainless Steel Anchor Chains

If your boat sports a nice shiny stainless steel anchor, it's essential that you attach it to a stainless steel anchor chain, using a stainless steel shackle to make the connection.

Otherwise dissimilar metals and galvanic corrosion will do what galvanic corrosion does - and fairly rapidly too.

Best stick to a galvanised anchor and chain in my view, and leave all the shiny stuff to the powerboaters.

But before you replace your anchor chain...

Make sure that it's compatible with the gypsy on your windlass. If it isn't, does your windlass manufacturer offer one that is?

And finally...

All data - dimensions, safe working loads and weights etc - stated in this article are approximate and are likely to vary according to the chain manufacturer. Before buying new chain, always check out the specification with the supplier.

Cruisers' Questions...

Should I Use Rope, Chain, or a Combination for My Rode?

A combination is ideal. Here’s why:

Chain Weight: A length of chain (often 20–30 feet at the anchor end) gives the rode weight, allowing it to lie along the bottom and reduce shock loads.

Rope Flexibility: The rope portion is easier to handle and provides some stretch to absorb sudden loads. However rope bulks up more than chain taking up more space in the chain locker than chain would.

Overall Benefit: The chain-to-rope combination gives you the best of both worlds—the chain’s dropping power and the rope’s shock absorption—resulting in a secure, adaptable anchoring system.

What Is the Rule of Thumb for Anchor Chain Length?

A practical rule is to have the chain make up about 10–20% of your total rode length. This ensures you have enough weight at the anchor end to keep the rode lying flat on the bottom. For many vessels, that translates into roughly 20–30 feet of chain at the end of your rope—though specifics can vary with vessel size, water depth, and sailing conditions.

How Long Should Your Anchor Chain Be?

While chain length depends on your setup, a common guideline is to use enough chain to satisfy the rule above (roughly 10–20% of your total rode length). In many cases, this means having about 20–30 feet of chain before the rope begins. This chain length is critical to add weight so that the rode doesn’t “catenary” excessively and can lay properly on the seabed.

What Is a G3 Anchor Chain?

A G3 anchor chain is typically a chain designated under a specific strength and load-bearing standard. The “G3” rating tells you that the chain has been engineered to provide consistent performance and a reliable weight for helping the rode lie on the bottom. It’s designed to offer sufficient durability and abrasion resistance for regular anchoring in common conditions.

What Is the Difference Between G4 and BBB Chain?

The differences generally come down to their tensile strength, construction, and weight:

G4 Chains: Often have a higher strength rating and increased load capacity. They may be thicker or built with different alloy compositions, making them ideal for harsher conditions.

BBB Chains: Are designed to balance cost, weight, and sufficient strength for everyday anchoring.

Always review the manufacturer’s specifications to see which chain fits your vessel’s needs and the conditions you face.

More about Anchors and Anchoring...

Flowchart: How to Anchor a Boat
This flowchart sets out the six key steps in anchoring a boat securely
Anchoring in Tidal Creeks and Estuaries
Anchoring in Tidal Creeks and Estuaries presents unique challenges for boaters. Learn essential techniques to secure your vessel safely in these dynamic environments.
Is an Anchor Snubber Line really Necessary?
If you have an all-chain rode then yes, you definitely need an anchor snubber line. But what's best, a single snubber line or a bridle? Well, it depends...
Methods of Joining Anchor Chain
Here’s how to go about joining anchor chain, either to another length of chain or by a rope/chain splice to a warp, and by a swivel connector to the anchor.
What anchor chain length is needed to keep your boat secure?
Too little anchor chain length and your boat is likely to go walkabout; too much and you're likely to swing into other boats. Here's how to get it right...