G4 chain vs BBB

[aliddell]

I have a Muir 850 windlass with a gypsy that specifies 5/16 BBB chain. Wondering if I could use 5/16 G4 or would I be asking for problems.
Thanks in advance,
Andy

[Adelie]

Originally Posted by aliddell

I have a Muir 850 windlass with a gypsy that specifies 5/16 BBB chain. Wondering if I could use 5/16 G4 or would I be asking for problems.

Thanks in advance,

Andy

Probably work, they are supposed to be the about same. Check the specified link dimensions for BBB against what's advertised by your G4 supplier.

Push come to shove many suppliers will sell you a 1' section just to verify suitability. Lay the piece on the windlass gypsy to check. Also get a micrometer and check the 3 major dimensions for thssmple and what you already have.

[Adelie]

I just checked 1st Chain Supply. There's about a 2.5% difference in length per 12 links for 5/16" BBB & G4. Get the sample and then see how that goes. If you don't already have BBB on the boat the get a sample of that too.

Is the boat marginal for that size BBB or just up grading to be cautious?

[aliddell]

Old chain is BBB but is toast (rust) so I am looking at replacement.

[Adelie]

So what's the deal with BBB vs G4? Added safety?

I just checked your boat specs against the ABYC anchor load chart which is generally considered to be very conservative.

For 42kt you could use 1/4" G4 and still be "Safe". ABYC says 1800lb loads, for your boat, SWL for 1/4"G4 is 2600lb (33% of breaking) or 1950lb (25% of breaking). 5/16"BBB is 1900lb (25% of breaking)

My sense from reading a lot of accounts of anchor failures is that the chain, even somewhat undersized is the strong link (pun intended) in the anchoring system. Failure of the nylon rodes is a much more likely, either to chafe, age, heat damage from previous storme, poor bow roller set up, . . .

[JOHNMARDALL]

The issue here is not necessarily the strength of the chain, as it seems to be a bit oversized for your boat, but rather, how well it fits the pockets in the windlass gypsy. It is doesn't fit will, over time it will wear the shoulders off the pockets and the chain will start to bounce and slip as you retrieve your ground tackle. With the advent of chain from China and other Asian suppliers, this problem of chain fit is sometimes exacerbated by poor quality control related to link dimensions.
If you've already got the chain you can try it, knowing that you may have to replace the gypsy and other damaged components of the windlass, but if you still need to buy the chain, I recommend staying with Muir's recommendation.
Good luck
John Mardall
Vetus Maxwell Group

[Sailorbob8599]

Originally Posted by Adelie

Probably work, they are supposed to be the about same. Check the specified link dimensions for BBB against what's advertised by your G4 supplier.

Push come to shove many suppliers will sell you a 1' section just to verify suitability. Lay the piece on the windlass gypsy to check. Also get a micrometer and check the 3 major dimensions for thssmple and what you already have.

The Gypsy is very simple to remove from a Muir Windlass; Why not remove it and take with you to the chandler, or chain supplier; after all, what will you do with a useless foot of chain after you've purchased it?

[Cheechako]

If you are over chained with BBB, I would stick with that if it fits the windlass well.

[gjordan]

Unless your chain is very rusty, look into having it re-galvanised. I am sure there are places in Fl that can do that. ____Grant.

[Adelie]

Originally Posted by Sailorbob8599

The Gypsy is very simple to remove from a Muir Windlass; Why not remove it and take with you to the chandler, or chain supplier; after all, what will you do with a useless foot of chain after you've purchased it?

I presumed online purchase and assumed that would be apparent.

[Emouchet]

The G4 chain will not fit in the BBB gipsy: as soon as there will be some tension, it will trip over the gipsy.
Without load, you may have the feeling that it fits. However, trust me, it will not work when you really will need the windlass to take that hook off the ground.

[CdS2 Roland]

Good morning every body,
have a look to the attached list.

[gjordan]

Alidell, over on the anchor forum I had started a thread titled "dimensions of chain". I was given a lot of information and links to chain dimensions that I think will help you. How much actual wasting of your existing chain is there? Rust can look horrible and not be serious. Re-galvanising is often a good solution since you know the chain is correct, and it is usually much less expensive. Maybe something to look into? Good Luck. _____Grant.

[Mcglashan]

Originally Posted by Adelie

Probably work, they are supposed to be the about same. Check the specified link dimensions for BBB against what's advertised by your G4 supplier.

Push come to shove many suppliers will sell you a 1' section just to verify suitability. Lay the piece on the windlass gypsy to check. Also get a micrometer and check the 3 major dimensions for thssmple and what you already have.

What is the 3 major dimensions.
I see the pitch, the inner link diameter, overall width, overall length and the wire thickness. 11 link dimension
I seen two 3/8 bbb chains with different dimensions, Titan vs Acco
Pitch same, wire dia different, inner dia same, of course overall with and length different. Now does the diameter dimension affect the fit on Gypsy, as you mentioned 3 major, what three major dimensions? I cannot buy test chains.

[GordMay]

NACM WELDED STEEL CHAIN SPECIFICATIONS

6.0 DIMENSIONS

6.1: The dimensional requirements of the various chain sizes and designations are given in Tables I throughXI.
The inside length dimension can be measured either by individual link or by measuring the span of100 links and dividing by 100.

6.2: The diameter of the material from which the chain is manufactured shall be the diameter as specified inTables I through XI within the following tolerances: -3% for Grades 80 and 100, -7% for all other chains.Oversized material may be used for all applications.

➥ https://www.fehr.com/img/product/des...ifications.pdf

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