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Training Wheels · 05-06-2017, 10:45

Quote:

Originally Posted by Bluebeard

Only Benz has really commented on the dissimilar metal corrosion that you will get using SS onto galvanized chain.
Whichever SS you use it will be noble with respect to the chain, and anchor.
But the chain being the thinner component will be the weak link if it is allowed to corrode.
The chain link attached to the shackle will act as an anode and corrode in preference to the shackle.
Why not use a good quality galvanized shackle like a Green Pin?
And you side step concerns about grade of SS and its WL/Breaking strength.

There's not a galvanized shackle that meets the breaking strength of 1/4" G70 chain that will fit the chain. A 5/16" Wichard HR has a BS of 9700#.

**Dockhead** · 05-06-2017, 10:49

Quote:

Originally Posted by estarzinger

mmmm . . . . .we used a wichard HR shackle for about half a decade. I put it on when a prior rated galvanized one started rusting badly and we were in the middle of no-where.

We had previously bent/broke a high end SS swivel, so it was not like we were babying our ground tackle.

This is not to suggest it was the best/perfect material, but it was fine, no problem. I used it simply because I had it on board, it had a nice flush Allen key head which ran smoothly, and it seemed sufficiently speced to do the job. When we got new chain, we swapped it out for a new rated galvanized one - but not because I had any real concern about it.

I use the exact same Wichard shackle in my ground tackle. I change it every few years.

I am aware of the potential drawbacks of stainless, but I chose it because it was the only shackle of adequate strength, which I could get to fit. I would have preferred galvanized proof tested, but there wasn't any such thing. It was also much easier to use it with the flush Allen key head, compared to cutting the ears of a normal galvanized shackle and drilling a mousing hole etc. -- bleh . . .

Like Evans, I've had no problems of any kind. I think crevice corrosion is probably a bigger problem on (a) lesser quality goods; and (b) shackles which are constantly underwater, that is, constantly oxygen deprived, like on a mooring. For an anchor shackle which spends most of its life in air, it doesn't seem to me like it's as much of a problem. I'm not an expert, but my experience is one data point.

In any case, quality is important, and the forged Wichard stuff is really top notch, and not all that expensive for what it is.

Bluebeard · 05-06-2017, 12:04

Quote:

Originally Posted by Training Wheels

There's not a galvanized shackle that meets the breaking strength of 1/4" G70 chain that will fit the chain. A 5/16" Wichard HR has a BS of 9700#.

I may be barking up the wrong tree, but 1/4in chain has an inside width of .46 /.48in ie greater than 7/16 or 11mm.
Also G70 has a BS of 4 x WLL or 4 X3150 = 12,600 lbs

A 1tonne WLL Green pin has a pin diameter of 11mm so fits and a BS = 6 x WLL or 13,200 lbs

All of which confirms my intuition that high alloy carbon steel is as strong or better than any stainless. If the opposite was true then the heavy lift boys would be using SS alloy shackles, and they don't they use Green Pin or Crosby.

Can I also ask why you are using G70? By using lighter chain you are losing one of the real benefits of using chain - the catenary effect.

Training Wheels · 05-06-2017, 13:08

I tried a 3/8" galvanized alloy shackle, wouldn't fit.

Weight, weight, weight! A multihull thing ya know, we even use backpackers plastic and aluminum utensils......... I know, I need an intervention. But, I'd rather go smaller diameter chain but carry a longer length, for the same weight. Did I mention I am the windlass?

Thanks everybody for the brainstorming! Please, any more ideas or experience? So far, I'm leaning towards using the Wichard HR shackles, love the idea of the soft shackle back up, and change them out every year or two.

**estarzinger** · 05-06-2017, 13:10

I was told once that you could take a large tapered steel pin and hammer/hydraulic press it into the middle of a chain link, to make it more round/less oval, so it would then take a bigger shackle pin, and it would do no damage to the strength of the chain link - anyone know how true that is and does it still apply to g70?

knockabout · 05-06-2017, 13:38

we fitted 50kilo of 6mm short link 316 anchor chain approx. 12 months ago / connected to the galv claw anchor with a 8mm 316 anchor swivel and 2 8mm 316 shackles / moosed with 316 moosing wire so far all going well.
we had a cast stainless shackle approx. 6mm fail through corrosion it was the bottom shackle on the bobstay fortunately we were in the mudpen not sailing when the rig made a noise and the stainless bobstay was left dangling from the bowsprit / replaced with 316 and still going well but will check for wear on the curved part of the D
the cast shackle failed through the threaded eye by corroding and crumbling apart/ we have been using stainless anchor swivels in galv chain for 15years without any problems they outlast the galv chain / that's why we changed to stainless chain / some shackles stamped 316 look like they are cast / we had a stainless thread eye fail causing the top 2metres of our at the time fractional rig to break and fall forward due to the pull of the headsail / the eye had corroded inside where the pin had worn it slightly and didn't give any warning sign / we hacksawed the broken top of the mast off cleanly while at anchor behind cape flattery and sailed with 1 reef in the main to Darwin where we fitted the existing rig / close inspection of all rigging screws at the time / the screws connected with cast shackles had wear / the softer 316 shackles weren't wearing the eyes in the rigging screws as much it might come down to the pins in the cast shackle being a different alloy and hardness / as a precaution weeded out the cast shackles and used them in places of less stress when fitting the masthead rig we are still using/ off topic a little that was in 2006 / some of the cast shackles are still in use on the dinghy / we gave 2 to a friend connecting an ornamental chain at his house / they looked alright but due to suspicion of dissimilar metal corrosion between different types of stainless it was easier to stick to all 316 / are you confused yet?/ a solid quality marine stainless shackle that's been proofed by the manufacturer should be o.k

Bluebeard · 05-06-2017, 13:57

Quote:

Originally Posted by Training Wheels

I tried a 3/8" galvanized alloy shackle, wouldn't fit.
. . . . . .

Just goes to show you should believe very little you read on the internet.

Snowpetrel · 05-06-2017, 14:04

Quote:

Originally Posted by estarzinger

I was told once that you could take a large tapered steel pin and hammer/hydraulic press it into the middle of a chain link, to make it more round/less oval, so it would then take a bigger shackle pin, and it would do no damage to the strength of the chain link - anyone know how true that is and does it still apply to g70?

I've done this with g30 and g40 chain 6mm and 8mm chain. I used a big steel Marlinspike, big hammer and a vise.

It took a fair bit of force to open it up by 0.5mm to 1mm or so and may have damaged the galvanising slightly, but being able to get a decent sized rated shackle through the chain is nice.

There is some variation in each link. So its worth measuring and cutting back to the widest link you can find first.

Not sure about any strength loss. In theory prehaps it seems like there might be, in practice I don't think its a big factor.

Snowpetrel · 05-06-2017, 14:10

It seems there would be a market for this type of anchor shackle. It has an ovalised Pin for far greater strength.

Common in big sizes, we use these and kenter shackles on ships anchor all the time, but Ive never seen a small galvanised one.

**Dockhead** · 06-06-2017, 00:14

Quote:

Originally Posted by estarzinger

I was told once that you could take a large tapered steel pin and hammer/hydraulic press it into the middle of a chain link, to make it more round/less oval, so it would then take a bigger shackle pin, and it would do no damage to the strength of the chain link - anyone know how true that is and does it still apply to g70?

You can also have your chain made with an enlarged end link. I actually have this, but a larger shackle than what I have wouldn't run well through my bow roller.

stillbuilding · 06-06-2017, 01:23

Quote:

Originally Posted by Glenn.Brooks

Iam curious, has anybody ever seen a SS shackle with the remotest hint of crevice corrosion? 45 years commercial fishing in Alaska and sailing, I never have.

Sure, dredge something up off the bottom after 40 or 50 years, it's gonna be corroded. But, really, anchor rode needing a small 1/4" shackle? small craft with such light weight rode is likely never going to be in a position to put such a strain on that size shackle that it will deform. Use either galvanized or SS, it won't matter. You will be safe either way.

[CanATTACH]149265[/ATTACH]

You mean like this shackle?

Attached to the anchor, not used for 1 year and broke open on first use - damn near lost me the anchor. Chinese of course.

**Dockhead** · 06-06-2017, 02:48

Quote:

Originally Posted by stillbuilding

[CanATTACH]149265[/ATTACH]

You mean like this shackle?

Attached to the anchor, not used for 1 year and broke open on first use - damn near lost me the anchor. Chinese of course.

That does not look like crevice corrosion to me. Looks like a simple case of poor casting.

Another good lesson to never ever use something cheap or unbranded or of questionable quality anywhere in your ground tackle!!

double u · 06-06-2017, 03:14

Quote:

Originally Posted by Training Wheels

It seems those are no longer available from Maggi. As I understand, they bought them from another manufacturer and had them galvanized, which the manufacturer recommended against.

as of ~2 months ago they still quoted them to us...