Shackles

[rolandgilbert99]

Most cruising boats are heavy, mine is around 28,000 lbs. I am wondering if the shacles attached to the anchors are strong enough? What kind of shacled serious cruisers are using for 5/16" HT chain?

[ggray]

3/8 Crosby 209A

[beetle]

For 5/16" grade 40 HT chain, I use a 7/16" screw pin load-rated bow shackle:

Alloy SPA Shackles

- rob/beetle

[Cheechako]

I have used Wichard SS shackles (uh oh...here we go!) They are rated like...I dont know something like 20,000 lbs. Never had a corrosion problem.

[skipmac]

Originally Posted by ggray

3/8 Crosby 209A

+1, That's what I've got on my chain.

However, I tried an experiment with a SS shackle. Needed to attach a 1/2" chain to my tractor to pull some stumps. The only thing I had on hand that fit was a large SS shackle in my boat spares so figured why not give it a shot and if it breaks, no loss. It's not like putting your boat on the rocks.

I always thought SS was not as strong as good, alloy steel, more brittle, etc. Well 6 years and dozens of trees later that shackle is still there. Bent like a pretzel and would probably take a grinder to get the pin out but that shackle has dragged around green oak logs 3' diameter, 20' long and taken snatch loads that lifted the front wheels of the tractor off the ground.

I cannot imagine the loads on an anchor would be worse than what I've put it through. In fact I've never seen a shackle on a boat as distorted as this one. Makes me wonder if SS shackles might really be OK. Sure wish I knew who made this one. Wouldn't mind having a few more like it.

[David M]

Given everything else is equal, high quality steel is stronger than stainless. You see this with wire ratings of the same diameter.

[Laidback]

If the chain is 5/16" HT - then a shackle with a pin that will go through the chain tightly should be enough - But the Shackle must be of high breaking strength.
Have a look at this ite for detailed info := McMaster-Carr

[Cheechako]

Regular 300 series SS is slightly less strength than good low carbon steel. The Crosby are likely good steel, unless the bean counters have started running the company lately. The average anchor shackle at your local hardware or Marine store is likely not good steel...or a turkey shoot at best. Exotic stainless alloys like Wichard uses (on some things) are way stronger than 304/309 etc SS. However, as strength goes up in higher strength SS and Steel, usually it is more likely to break near the working strength rather than deform. That's the short version anyway!
FYI: Wichard forged 309 captive pin 10mm (3/8) shackle: 5200 KG breaking strength.

[barnakiel]

The shackle will be one size up from the chain. HT from e.g. Wichard, if you are the worrying type. In any case - avoid Chinese cheapo.

b.

[evm1024]

Originally Posted by ggray

3/8 Crosby 209A

+1 from me too. The 209a is a high strength alloy shackle. Buy them at your local industrial rigging shop for about the same price as a non alloy shackle. No need to use anything less.

Regards

[janders]

Originally Posted by ggray

3/8 Crosby 209A

+1

I no longer buy shackles at a chandlery.

[Mark Johnson]

I suggest the Crosby 3/8" HT shackle. They are the best!

M.

[foggysail]

Somewhere in my travels, I accumulated a couple of cheap shackles. Maybe they were the only ones available. THEY WERE TERRIBLE! Never again would I use a cheap/inexpensive shackle. My advice is be careful, use a good quality, drop forged shackle.

[Dockhead]

To get a complete picture of this issue, you really need to search the archives and read up on it. Shackles tend to be the weakest link in your ground tackle and so extremely important to get right. There are lots of differents views on it and you will need to spend some time reading before you start to get a grasp.

Some other good sources are Vyv Cox's site:

Connectors

And the stuff on shackles at Rocna:

Shackles (Rocna Knowledge Base)

Swivels (Rocna Knowledge Base)


The subject is complicated, involving the need to swivel or lack of such need, pros ad cons of stainless versus galvanized, the issue of getting the anchor connector over your bow roller, and the issue of where your connector should be attached.

I don't recommend making any decision on the basis of anyone's pat answer, but if you insist on a pat answer, mine would be:

1. Use best quality colored-pin galvanized shackle IF (a) you are able to deploy and retrieve your anchor without need for a swivel; AND (b) such a shackle will run smoothly over your bow roller.

2. Otherwise, use the best quality and most massive stainless swivel you can find, like a Kong.

I had both problems with a shackle on my own ground tackle -- anchor would come up wrong way around wthout a swivel, plus a shackle of adequate size would not fit over my bow roller. So I went with a massive (and massively expensive) Kong swivel. Since it's rated stronger than the chain even in a side pull, it seems to be strong enough to not be a weak point in any conditions. But if you can use a colored-pin galvanized shackle, this is safer (almost can't be put in a position to be under side loads), and besides that vastly cheaper.

There is no advantage to stainless over galvanized if you're talking about a regular non-swivelling shackle.

But swivels need to be stainless, because the moving parts will bind if they are not stainless.

Don't forget to mouse your shackle pins.

That's the way I see it, in a few words, but again, you would be better off reading up on the subject and making up your own mind.