3/8 BBB or 3/8 G4 HT dilemma

[skipmac]

Originally Posted by GordMay

“G70" Transport Chain is usually finished in Yellow Zinc Chromate, What brand is your galvanized G70?

Acco makes a "marine" grade galvanized G70 and I believe also the Italian chain company Maggi as well.

https://www.peerlesschain.com/produc...ndlass-Chains/
'

[evm1024]

Originally Posted by GordMay

“G70" Transport Chain is usually finished in Yellow Zinc Chromate, What brand is your galvanized G70?

Not transport chain.

As noted in the prior paragraph it was Acco which I sourced through West marine

5/16" G70 (acco) feeds quite nicely

[hpeer]

Give this source a try.

Fairly practical and knowledgeable.

I think he will s ll you 1’ pieces to try put.

https://www.1st-chainsupply.com/chai...lass_chain.htm

[GordMay]

Originally Posted by evm1024

Not transport chain.
As noted in the prior paragraph it was Acco which I sourced through West marine
5/16" G70 (acco) feeds quite nicely

Interesting.

... The most common chain grades used for anchor rodes on recreational boats are G30, G40, G43, and G70. Chain marked as G30, G40, or G43 is made from carbon, or mild, steel. Chains denoted as G70 are heat-treated steel, commonly quenched and tempered (the same process used for some anchor shanks).

Quench and tempered steels are made to specific chemical tolerances, as determined by manufacturer. The tempering temperature fixes the strength of the steel. If some post-manufacturing process, such as galvanizing, raises the chains temperature to the one used for tempering, then the chain is weakened.

Although you can galvanize the high-strength, tempered steel used in G70 chain, tempered steel should never be re-galvanized-a major drawback for anyone who plans to extend the life of their chain by re-galvanizing it. Although there are higher-strength chains- G80, G100, and more recently G120-galvanized versions of this chain are either non-existent or too new for us to recommend.

A confusing array of names applies to the same or similar chains. Some examples: G43 sometimes goes by High Test, HT, or HT4; G70 is often called transport or trawl chain ...

Excerpted from: Making Sense of Marine Chain Standards
➥ https://www.practical-sailor.com/sai...hain-standards

[s/v Jedi]

Early 90’s Steve Dashew specified hot dip galvanized 3/8” G7 chain for the Sundeer 64’s and same in 5/16” for the 60’s and 56’s. Since then, ACCO Chain had this as a special order option. We ordered it to replace our chain in 2004 incl. Enlarged end links and got that, incl. X-Ray report on the end links for $7.xx per foot. They welded the chain and end-links, then galvanized it.

I believe it has become much more expensive even without special ordering.

[Training Wheels]

We have used G70 ACCO chain, the problem is it seems the galvanizing isn’t as good. After 3 years I’m having to replace it because it’s so rusty. I’m replacing it with G43.

[evm1024]

Originally when I sourced the chain I did a bunch of research (that was back in Jan 2011) and the 5/16 G70 cost $4.50/ft.

Here is a link to the current HDG chain specs from Peerless:

https://www.peerlesschain.com/produc...G70-ISO-Chain/

Anyway (and don't quote me on it it has been some time and my memory grows faint) as I recall G43 and G70 chain used the same spec steel (or close to the same) with G70 getting heat treatment for improved strength.

The thought here is that when you re-galvanize G70 you remove some or all of the strength that heat treatment gave it. But because it is made of G40 spec steel then you chain at worst ends up with G43 strength.

And in my case because 5/16 G70 feeds in my windlass (and 5/16 G43 does not) were I to re-galvanize I would still have 5/16" chain that exceeds 3/8" BBB strength.

(let's not pettyfog over my use of the word strength please)

Here is the WLL in KG from the peerless site:

5/16" G70 WLL 1910 kg
5/16" G43 WLL 1770 kg
3/8" BBB WLL 1262 kg

[a64pilot]

I believe worst case if you regalvanize G70, you have close to G43

I also believe that the WLL for grade 43 and higher chain is derived at differently than it is for lower grades, that it’s stronger, but not as much stronger as the numbers should indicate.

On edit, the MBL or minimum break load for G43 and higher should be I believe four times the WLL.

[skipmac]

Originally Posted by hpeer

Give this source a try.

Fairly practical and knowledgeable.

I think he will s ll you 1’ pieces to try put.

https://www.1st-chainsupply.com/chai...lass_chain.htm

Agree. I got a lot of help from these guys when I was trying to figure out chain.

[rslifkin]

If I'm remembering this correctly, WLL is 25% of MBL on BBB, G70 and most other grades. WLL is 33% of MBL for most G43 chain. For 5/16 G43 vs 3/8 BBB, the MBL is 11,700 for the 5/16 G43 vs 10,600 for the 3/8 BBB. But WLL is 3,900 for the 5/16 G43 vs 2,650 for the 3/8 BBB.



Personally, I'm using 5/16 G43 on my boat and I figure there's no way I'd manage to exceed the WLL with this boat short of a direct hit by a Cat 2+ hurricane.

[GordMay]

Originally Posted by rslifkin

If I'm remembering this correctly, WLL is 25% of MBL on BBB, G70 and most other grades. WLL is 33% of MBL for most G43 chain.



For 5/16 G43 vs 3/8 BBB, the MBL is 11,700 for the 5/16 G43 vs 10,600 for the 3/8 BBB. But WLL is 3,900 for the 5/16 G43 vs 2,650 for the 3/8 BBB.

Personally, I'm using 5/16 G43 on my boat and I figure there's no way I'd manage to exceed the WLL with this boat short of a direct hit by a Cat 2+ hurricane.

Thanks for your patience.

Grade 43, 70, 80, 100 and 5/16" (8.4 mm) and larger Grade 30 chains shall have periodic embossing for identification purposes.
The number seen after the letter can be read as Newtons per millimetre squared or N/mm2. It represents the chain’s maximum stress, at ultimate strength.

Working Load Limit (WLL) is the maximum working load designed by the manufacturer; ie: the maximum load which should ever be applied to the chain, even when the product is new, and when the load is uniformly applied – straight line pull only. Avoid side loading.
This load represents a force that is much less than that required to make the lifting equipment fail or yield.

The WLL is calculated by dividing MBL by a safety factor* (SF).
* Working Load Limit is often 1/3 or 1/4 of the breaking strength (SF often = 3 or 4); but check your manufacturer's spec's.
Design Factor (safety factor) is computed by dividing the catalog Breaking Strength by the catalog Working Load Limit and generally expressed as a ratio.

Breaking Strength is the average force at which the product, in the condition it would leave the factory, has been found by representative testing to break, when a constantly increasing force is applied in direct line to the product at a uniform rate of speed on a standard pull testing machine. Proof testing to twice the Working Load Limit does not apply to hand-spliced slings.

The Proof Test Load (usually twice the Working Load Limit) is the load which the product withstood without deformation when new and under laboratory test conditions. The Proof Test Load does not mean the Working Load Limit should ever be exceeded.

NACM WELDED STEEL CHAIN SPECIFICATIONS
DEFINITIONS
3.1 Working Load Limit (WLL)
The "Working Load Limit" (rated capacity) is the maximum load that shall be applied in direct tension toan undamaged straight length of chain.
3.2 Proof Test
The "Proof Test" (manufacturing test force) is a term designating the minimum tensile force which has been applied to a chain under a constantly increasing force in direct tension during the manufacturing process.
These loads are manufacturing integrity tests and shall not be used as criteria for service ordesign purposes.
3.3 Minimum Breaking Force
The "Minimum Breaking Force" is the minimum force at which the chain during manufacture has been found by testing to break when a constantly increasing force is applied in direct tension. Breaking force values are not guarantees that all chain segments will endure these loads (see Section 5.2). This test is a manufacturer's attribute acceptance test and shall not be used as a criterion for service or design purposes.

More ➥ https://www.nacm.info/specifications...pecifications/

[vpbarkley]

My boat is equipped with 3/8 BBB chain. Links are stamped with the letters 3B.
I am changing over to 5/16 HT G43 ISO chain.
An 8mm-5/16" gypsy for my Quick windlass costs $342. It's 5 minute replacement.
The new chain in a 300' length is 200 lb lighter, 47% stronger and is less expensive.

[TBear60]

Some straight up comparison. Your existing 350 ft of 3/8" BBB weighs 560, or 1.6 lb/ft.
The 3/8" G4 weighs 1.49 lb/ft, so 560lbs of G4 gets you ~376ft.
This is not much gain, since you only get 8.7 ft more anchoring depth at 3:1 scope.
Putting in 400 ft of 3/8 G4 only increases your total weight by 36 lbs! Plus the G4 is 35% stronger.
But the extra 50 feet (over what you have) only gains you 16 more feet of anchoring depth.
However, if you install 425 feet of 3/8 G4, you get 25 ft more anchoring depth and only increase the weight (over what you have) by about 73.25 lbs. Good luck!

[a64pilot]

Originally Posted by vpbarkley

My boat is equipped with 3/8 BBB chain. Links are stamped with the letters 3B.
I am changing over to 5/16 HT G43 ISO chain.
An 8mm-5/16" gypsy for my Quick windlass costs $342. It's 5 minute replacement.
The new chain in a 300' length is 200 lb lighter, 47% stronger and is less expensive.

I think rlfiskin is correct, it’s stronger but not by a whole lot, but it’s certainly a lot lighter.
I know from working on the farm with chain that you’ll stretch and deform it long before it breaks, and who has stretched chain on a boat before? I’m sure it’s happened, everything has happened, but I bet it’s exceedingly rare.
I’ve never heard of it, or broken chain that wasn’t some kind of very suspicious chain, as in where it came from was unknown, likely pulled from some junk yard.

[Jim Cate]

I’ve never heard of it, or broken chain that wasn’t some kind of very suspicious chain, as in where it came from was unknown, likely pulled from some junk yard.

Yep! This is the point I was attempting to make in an early post. Agonizing about small differences in chain WLL or ultimate strength is a waste of energy for yotties.

Jim