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Anchor swivel or not?

rwthomas1

Sustaining Partner
The new rode/chain/anchor package isn't fitting together as smoothly as I would like. The 5/16" HT chain is supposed to have a 1/2" ID on each link. I selected a shackle with a 7/16" pin specifically for this reason. Guess what, the pin binds in the chain. Can't quite get the pin tight enough and even if I did, it would rotate with the chain link. I have a few options:
-Lightly grind the shackle pin
-Lightly relieve the first chain link
-Use a smaller shackle.

None of these solutions give me a warm fuzzy feeling. The reasons should be obvious? I'm considering using a stainless swivel like this one http://www.defender.com/product.jsp?path=-1|10391|33872|34760&id=1527514 at the end of the 5/16"HT chain, then 5 or 6 links of 3/8"HT then the shackle to the anchor. The failure problem with swivels appears to be when they are attached directly to anchor shanks. They fail when not pulled in a straight line, like when the tide or wind shifts and the anchor rode pulls the anchor in a new, non-linear direction,they are not intended to side load. The swivel in between chain sections should take care of this issue, offer the additional dubious benefit of "swiveling" and allow the use of a large shackle. The shackle is still the weakest link it the whole system.

What say the crowd?

RT
 

u079721

Contributing Partner
Well of course I can't find the reference right now, but IIRC I once read that a tempting solution to this vexing problem is to use a stainless shackle that has the same WLL but a smaller pin than a galvanized shackle. BUT, the reference (I think one of the Dashew's books) said that one ought not to mix galvanized and stainless in the same rig, as it leads to galvanic corrosion, and of course stainless is subject to crevice corrosion if buried in the mud and depleted of oxygen . But then how does one even attach the various stainless or aluminum anchors out there?

I like your solution to use the swivel isolated from the end of the shank, as that should address the main failure mode of these (though I've also read that their working load is not as great as the rest of the chain). I personally would probably keep it simple and grind down the pin of the shackle slightly and then see if I could get it re-galvanized before using.
 

Sven

Seglare
We use a shackle before the swivel, both stainless. We set it up that way because the beautiful swivel specifically said not to connect directly to the anchor for the reasons you state.



-Sven
 

MarkA

Please Contact Admin.
I made the bad mistake of using a stainless shackle to connect a galvanized chain to a galvanized anchor. After a couple years in the chainlocker, the swivel and several links of chain were toast, and so much rust contaminated parts of the nylon rode that I had to cut out 3-4 sections and splice it back together.
 

lbertran

Member III
3/8 Shackle

Have you considered using a 3/8" Crosby shackle? I believe that's the customary shackle size for 5/16 chain. Crosby red pin shackles are quite strong.
 

rwthomas1

Sustaining Partner
I have a 3/8" Crosby shackle. The pin is slightly oversized or the chain is slightly undersized. Dunno which but it is irritating. Have done some test anchoring but nothing more, the pin is firmly stuck in the first link and rotates with it. Can't seize it like that..... RT
 

lbertran

Member III
I See

Sorry, I just re-read your OP and realized the 7/16" is the pin not the shackle. I have a 3/8" Crosby on my 5/16" G4 HT chain and it fits well. There must be some variation in tolerances though I wouldn't have expected that. I was forced to use two shackles, the 3/8" shackle connects to a larger Crosby that was necessary to properly fit my Manson Supreme anchor. But this arrangement seems to be working well.
 

rwthomas1

Sustaining Partner
Sorry, I just re-read your OP and realized the 7/16" is the pin not the shackle. I have a 3/8" Crosby on my 5/16" G4 HT chain and it fits well. There must be some variation in tolerances though I wouldn't have expected that. I was forced to use two shackles, the 3/8" shackle connects to a larger Crosby that was necessary to properly fit my Manson Supreme anchor. But this arrangement seems to be working well.

That is interesting. I too have a Manson Supreme with the Crosby "red pin" shackle and 5/16" HT G4 Acco chain. Clearly there are some variances in manufacturing. My question would be why do you need a larger shackle for the Manson? The 3/8" shackle fits the Manson fine, at least it seems too....

RT
 

lbertran

Member III
Interesting

It very well may fit. Truth is, I just moved up to the 5/16" chain rode from my previous, undersized, 1/4" chain (I was obsessing about weight forward for a while). The 5/16" shackle that fit that chain wouldn't fit the Manson. When I got the larger chain, I didn't even check if the 3/8" shackle would fit the Manson. Thanks for the feedback. But as I said, this arrangement seems to be working well, the anchor usually comes up to the roller in the correct position for storage.
 

Sean Engle

Your Friendly Administrator
Administrator
Founder
I just used galvanized shackle to galvanized chain - no swivel. I looked at it, and the small amount of metal the load would be transferred to made me nervous - and I have enough trouble sleeping as it is.... I figured if the boat turned all the way, the anchor would just re-bite. I had a Bruce - and was in several big overnight blows (Puget Sound/San Juan Ise) - no issues whatsoever (great anchor!)...

I think it's better to go simple and keep your eye on your hardware - and never mix metals....

//sse
 

rwthomas1

Sustaining Partner
I'm still trying to decide what the correct solution is. I'm not too concerned about the dissimilar metals issue. If this was a constant load situation, or the anchor was being used for extended periods, then I might be. But up on the deck, open to weather, the loose almost constantly moving contact points, I just don't see it happening. I have read plenty on failing swivels, usually attached directly to the anchor shank, but never heard/read a peep about dissimilar metals corrosion in this application. RT
 
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