Tidbit: Anchor Chain Splicing Considerations [Updated Oct-2024]

This is one of a series of brief, no nonsense posts that we call a Tidbit:

noun; small and [possibly] particularly interesting items of gossip or information...

The purpose is to share succinct posts about lessons learned, or things we use or do that work [or don't...] that are common to many of us boaters. 

The goal is to garner feedback from those of you having first-hand experience with a better approach/ solution/ product...  

We never assume what we are sharing is the ideal or only; it just seems to best suit our needs [and/or habits and/or budget] from our experiences thus far...

Sometimes these Tidbits originate from a topic of discussion on one of the forums we participate in, and this happens to be one. [The original forum response- which includes additional details- is appended below.]

Since we encounter this question fairly often- and since it may affect other boaters- it made sense to post a more detailed response for future reference.

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Alternate title: Extending the length of chain anchor rode

This article relates to ground tackle and chain sizes typically used by cruising vessels today up to, say, 60 feet in length.  

e.g., 1/4 — 7/16 inch (and metric equivalents) Grade 43 (ISO and DIN) anchor chain. 

Grades higher than 43 (e.g., Grade 70) are a different matter and require different connectors than those discussed here.

For our needs, splicing two or more lengths of anchor chain together requires a joint at least as strong as the chain being spliced, and the joints need to pass through the windlass gypsy smoothly. 

Note: Our requirement to smoothly pass through the windlass under load limits our choices somewhat. Therefore we will only discuss what we have used and tested in our windlass. 

There are other options available that are at lease as strong as the chain including:. Omega links; 2 shackles; soft shackles; etc., but these options won't pass through our windlass under strain. [Note that I didn’t include Quicklinks as they are not strong enough for our use case…]

Additionally- under the heading of other options- we don't hesitate to use an appropriately sized and constructed soft shackle as an emergency ground tackle joiner, or as back-up for [installed in addition to] shackles or other chain joints. 

What to use?

Most of us immediately think of C-Links for joining lengths of chain:

Unfortunately, even quality forged C-Links [matching chain size] are weaker than our G43 chain. [Substantially weaker in fact; more below...]  

Are there options that will meet our criteria of being at least as strong as our G4 chain, and work with our windlass?

We are fortunate that our horizontal anchor windlass tolerates a twin-clevis link matching the chain size: 

We realize this may not work in some (many?) windlasses under load.
But it is cheap to test, and we think they are worth having on hand anyway...

Following are a couple of short videos of a double-clevis traversing our windlass gypsy under load:

The next video is in slow motion and shows a worst-case scenario of our worn 10 year old chain jumping on the gypsy under load.  Close scrutiny reveals it is not the double-clevis connecting to the length of new chain causing the jump; in fact, it is what catches after a one link hop.  Also note the chain tries to jump a second time, but the double-clevis holds despite being the link connected to the hopping link…

Note: We have since encountered one double-clevis orientation that sometimes stalls the windlass: when it is oriented with the cotter pins facing the chain stripper. [i.e., cotter pins facing the center of the gypsy.]  If this happens under a fair load, the double-clevis jams at the stripper, necessitating reversing it out and rotating the orientation 90° in either direction.   

This doesn’t seem to happen unless under relatively high load. Therefore I try and watch for this orientation, and stop the double-clevis before the windlass and rotate the chain slightly before proceeding; a fairly uncommon event.

You can find good forged and galvanized twin-clevis links  [with SS cotter pins…] in the US$10-$15 range for the typical chain sizes we are talking about here.

The twin-clevis has the added advantage of being quick and easy to install and remove.

Some additional comments about C-Links: 

We haven't used C-links since we have always had very good results using a twin-clevis links, and prefer not to introduce known weak links into our ground tackle system. 

But we do keep some C-Links on hand in case they are ever needed. [If we used one, we would back it up with a soft shackle to back-up a C-Link as mentioned, above...] 

Tip: If you do end up using C-Links, be aware that peening the 'rivets' removes the galvanizing from the rivets, so those tiny rivets soon begin rusting away. 

I have heard from several other cruisers over time thay they found the two halves of a previously peened C-Link loose on their chain because the tiny rivets rusted off over time. 

It has been suggested [credit to Evans Starzinger] that gluing the two halves together with 5200 when installing [before peening the rivets] will likely help mitigate the risk of them separating.

I would also back them up with a soft shackle if I used them on my G43 chain. 

Lets compare these two chain joiners for strength, but first we need to decide which relative strength values to compare.

Tensile [minimum breaking] Strength is more important than Working Load Limit [WLL; Maximum (safe or suggested) working load] for evaluating the strength of components in our ground tackle system.

This is because WLL is based upon an arbitrary Safety Factor [ratio of Tensile Strength] which can (and does) vary by product, country, and sometimes even reselling vendor*. 

But the Minimum Breaking Point [Tensile Strength] is fairly consistent among similarly manufactured components.

We cannot always easily find the Tensile Strength for specific ground tackle components, but the WLL is often listed. 

But what may not be readily available is what safety factor [e.g., 3:1? 4:1?, etc.] that was used to establish the WLL. [e.g., 1/3rd or 1/4th of minimum breaking strength...?]

When doing the math to make sure a component is at least as strong as your chain, remember the connecting links we are discussing [forged C-Links and forged twin-clevises] are listed with a 4:1 safety factor, but our [US made G43] anchor chain is- for some reason- listed with a 3:1 safety factor. [A more conservative 4:1 ratio is used in Europe for G43 chain...] 

Note for reference [again in the US...] that G30, and G70 chain and above are listed using a 4:1 safety factor... [Perhaps to stay consistent with the vagaries of our archaic system of measurement?] 

See the Practical Sailor article in the Additional Resources section below for further elucidation.

Matching our chain with joiners of adequate strength:

We use 5/16" G43 ACCO [US made] chain listed with a 3,900 lb WLL.

With a 3:1 [US only] safety margin for G43 chain; 3,900 x 3 = 11,700lbs Tensile strength. [Minimum breaking strength; nominal]

A 5/16" forged Crosby C-Link is listed using a 4:1 safety margin and a 1,950 lb WLL. Therefore, Minimum Breaking [or Tensile Strength] = 4 x 1950 = 7,800 lbs. [vs. 11,700 for the chain; 33% weaker than the chain; your call...] 

See the C-Link Testing by Cox Engineering for more information.

Now do the math for a 5/16" forged twin-clevis link: [4,700 lb WLL @ 4:1] and you will find it is much stronger than the sames size G43 chain.

Bottom line: if a twin-clevis link will work on your windlass, that is the next reasonably priced, and substantially stronger choice [i.e., not weaker than the chain it is joining...] for joining our size G4 anchor chain [This applies up to 1/2 inch G43 chain size- which is as far as I looked...]

Don't forget to apply this same principle when selecting which anchor shackles to use in your ground tackle system... [There is a similar shackle discussion with product links on our Ground Tackle page if you desire more details.]


Another use for the double-clevis: 

We also use a double-clevis to attach the rope anchor rode [warp] to the main anchor chain.

We splice the 12 plait Dacron warp [Sampson Tenex] to a short piece of anchor chain. [e.g., 2 ft] 

From our Ground Tackle page
[which includes splicing instructions and many other references...]

We then connect that short piece of chain to the bitter end of the main chain rode using a double-clevis. 

This saves us having to redo the rope-chain splice whenever we end-for-end the anchor chain. Instead of cutting the rope and re-splicing to the chain, we only have to remove one cotter pin and replace it when reassembling. 

This works especially well for us because the rope-chain splice is rarely- if ever- deployed...

We are also experimenting with splicing the rope directly to the pin in a double-clevis; eliminating the short piece of chain.   

Why? Because sometimes the chain link the rope is spliced to rusts prematurely- perhaps because it is often kept wet with salt water from the saturated rope- eventually requiring a re-splice. 

If the pin the rope is spliced to in a double-clevis rusted, it could be removed and replaced without having to re-splice the rope. A small but useful gain.

Please let us know if you know of or have used other types of chain connectors that meet our two basic criteria. Thanks!

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Related Resources:

• All about chain types
• *Making Sense of Marine Chain Standards [Practical Sailor Article]
• ACCO Grade 40 [G4] ISO windlass [anchor] chain specs and source [occasionally the best prices I have found in US...]

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Link to original post [13-Dec-2018] which includes additional details...

Quote:

Originally Posted by GrowleyMonster  What make of windlass do you have? The double clevis rides properly in the wildcat in both the horizontal or vertical orientation, or do you have to make sure that it is horizontal?

GM,

Your question makes me realize I didn't provide enough clarity- sorry about that...

I have a horizontal capstan windlass [Lighthouse 1501] with dual 5/16" ISO chain gypsies. [Here is that project— with photos and links— if you are interested...]

What I intended to say is I only have experience with the twin-clevis chain links on my horizontal windlass. [~90° chain wrap.]

If I understand your question correctly, you are asking if the twin-clevis needs to be oriented horizontally in order to feed through the horizontal wildcat. I have tested it both ways and orientation of the twin-clevis doesn't seem to matter. It is worth noting that the twin-clevis link doesn't quite nest into the wildcat like a link of chain does, but it does well enough not to cause the chain to skip/jump- even under load. [However, I will add further link orientation testing to my list next time I have to end-for-end the chain on the docks. The windlass has a manual kedging socket (>10k lbs pull) so I can easily/safely perform some higher load tests...]

You didn't ask, but to close the thought and extend this question to using a vertical windlass: I have no experience, and have not tested it. However, since the chain wrap is typically greater on a vertical windlass [e.g. ~180° compared to ~90° on a horizontal windlass] I would speculate that it would work just as well— if not even better than a horizontal capstan. [i.e., more links to grip, ostensibly further reducing the risk of the chain slipping/jumping.]

It is certainly a cheap experiment to try on any windlass, and I believe some forged twin-clevis links [and C-Links] are handy to have in the cruiser's groundtackle tool box at any rate...

Please let me know if I misunderstood.

Cheers,  Bill

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