Galvanised v, Stainless

[ccscott49]

Why do lots of people insist on using a stainless shackle to fix there galvanised anchor to galvanised chain? It's just a recipe for rust on anchor and chain?
Why not use a certified galvanised shackle?
I see/hear lots of people do this.

 

[charles_reed]

I suspect

it's because it's what's to hand.

In principle I agree, MS is stronger, less prone to fatigue and far, far cheaper.

It does, however, rust. Frequently immovably.

 

[Salty John]

Perceived strength, precision and suitability for salt water, I suppose.
Some chandlers quote the same SWL for both but some chandlers quote significant differences for s/s versus galvanised. For instance, Force 4 quotes 416kg for a stainless 8mm bow shackle and 200kg for a galvanised version. Faced with such information I'd choose the stainless shackle.
I would choose galavanised if I had the choice, but in my experience the rusting issue, caused by wearing the galvanising off the partner components, is not that serious.

 

[ccscott49]

The rust is not caused by wearing the galvanising off the chain/anchor it's a dissimilar metal problem, galvanic scale etc.
That's why I wondered, you can get certified galvanised shackles which are very strong.
I also wouldn't put my trust in what an average chandler says about the strength of a stainless shackle, he or his suppliers probably sourced in the far east.

 

[bluedragon]

I have a different observation to you on this topic. There are many boats on our pontoons where the chain and anchor are rust-free, but the shackle is completely rusted (all over). Walking on Cardiff Bay Barrage this morning, there are safety fences made of galvanised posts and chain. ALL the shackles are rusted, but not the posts or chain. Now, I assume the quality of mass produced galvanised shackles is now so poor, that people go to SS. The availability of certified versions (which may or may not have better quality galvanising?) is very limited in local chandlers in my experience. I've got some mail order from Jimmy Green, but not locally.

 

[srp]

Most so-called galvanised shackles you buy in chandlers aren't - they're electroplated, which is totally unsuitable for marine use. Proper galvanising involves dipping in molten zinc, and most chandlers don't seem to know or care about the difference. Decent galvanised shackles are hard to buy these days - as ccscott says you'd need to get certified shackles, probably from a decent rigging company (like Spencers if you're on the IOW).

 

[bluedragon]

Interesting! But are certified shackles necessarily properly galvanised?

 

[Channel Ribs]

I quite agree. /forums/images/graemlins/smile.gif

That is one of the reasons I carry mainly stainless shackles, when supplying chain which is of good quality and a hot dipped anchor the weak link is going to be a rough shackle.

The plated ones I do use tend to be for shore based things like attaching the landrover to things. /forums/images/graemlins/cool.gif

 

[srp]

No, unless you ask for galvanised certified shackles! The last ones I bought for my pontoon mooring chain were, and had a yellow paint mark on the pin. I've also seen green paint marks on non-galvanised ones, but I'm not sure what that means.

 

[Guest]

It is very simple there is not a galvanised shackle that will stand up to the life. In the UK OK probably, but elsewhere they can not stand the coral or salty hot conditions.

They have threads which can not be sealed and after a short time on the foredeck or down below they become seized and useless.

If it is such a problem why have we got anchors sitting in stainless bow rollers with aerated sea water washed onto them daily.

Just looking at the area difference between a chain and a shackle compared to a propeller shaft and its tiny anode.

Most galvanising is removed by use, sand and rocks not by electrolysis. Other wise the shank of my anchor would be more rusty than the blades!

PS what bolts do you use to attach the anodes to the hull? If it was a problem then you would be using up lots of your anode just to protect the bolts!

 

[pyrojames]

Re: I suspect

http://www.eyecochain.com/shackles_greenpin.asp for top quality chain shackles etc on the East Coast. By far the best galvanising I have found. No connection etc etc.

 

[misterg]

[ QUOTE ]
Decent galvanised shackles are hard to buy these days ...

[/ QUOTE ]

May I humbly suggest (again) Gael Force who seem to have a range of qualities / prices to choose from. (No connection, other than as a satisfied customer, etc. etc. )

I agree about cr*ppy, zinc plated stuff in chandelries. I would choose glavanised over stainless every time, unless you had a stainless chain / anchor. One thing to be wary of when looking at load ratings is that the 'failures' they are based on may be different: The SS one may well break at failure, whereas the galvanised one will probably have 'failed' due to distortion, and will continue to hold things together at much higher loads.

To stop the pin seizing, I put a few drops of blue Hylomar (non setting gasket goop) on the ends of the pin before doing it up. (Obviously no good for a shackle that's undone regularly, but has worked a treat on the one on our mooring strop for the last 2 years. It certainly beats hanging over the bow sawing through 1/2" or more of steel with a junior hacksaw to get the strop off at the end of the year.)

0.02p

Andy

 

[Salty John]

You are technically right regarding the galvanic scale and the potential for bi-metal corrosion, but before everyone rushes out and changes their stainless steel shackles for dodgy galvanised ones let me put it into perspective. In researching an article on anchoring I considered this problem and I asked the Association of Galvanisers, or some such august body, for their comments. They referred me to a report which said '....however, when austenitic stainless steels (300 series) are in contact with zinc (galvanising) neither material will suffer additional corrosion, or at the most, slight corrosion. The slight corrosion is usually tolerable when in this bimetallic contact.' They go on to say that where there is a massive amount of s/s and a small amount of zinc, such as a zinc rivit in a s/s plate there will be corrosion of the rivit. In the chain application the contact area is so small that there will be no noticable effect, except if the zinc surface has been eroded away.
I think this is a non-problem and the choice of gavanised or s/s should be made on the basis of other factors.
All IMHO, of course.

 

[ccscott49]

To answer one of your questions, I use galvanised bolts, special ones, for holding my anodes on, dont you?
I certainly wouldnt use stainless. I also have no problems with rust on my shackles as I use galvanised certified shackles for my anchor and yes my anchor does take some hammer and a lot of galvanising has worn off.
I also know the threads rust and sieze, but I dont find this a problem, because I only very, very infrequently want to undo the anchor shackle and if it's siezed, cut it off and put a new one on. Not too difficult a job with a hacksaw, piece of wee wee with a dremel.

Tell me this, why is it the links closest to the anchor and stainless shackle rust like hell and the rest of the chain doesnt? and the anchor at that point also rust like blazes? tell me also why galvanised shackles rust like the devil, when used to connect stainless wire in rigging or other jobs, when you explain all that to me, I'll listen with wide open ears!

 

[alec]

Interesting thread.

I use s/s simple because my anchor has to be located on deck. With galvanised shackles the rust bleed soon makes an awful mess.

I have obtained and used galvanised shackles with the BS standard etched into them. I find that they soon go rusty as well. Agree that galvanised shackles from chandlers are normally very poor quality. But not easy to source good stuff these days.

I used to help lay and check moorings. It was very common to see one duff link on say the ground chain. This one link would be about half the thickness of the rest. Have no idea why this should happen.

 

[Guest]

I only have one anode other than the shaft. It is held on with a stainless bolt. Also MG Duff sell stainless bolts for the very purpose.

Not that I have ever lost even 10% a anode either.

I have 3 anchors for different bottoms. OK the fisherman's has only gone for a swim once but to swap the chain in a critical time just needs a large Allen key.

The last links of my chain rust because they are the only ones that are exposed every day. The rest is in the anchor locker or tube.

As I said my anchor is most rusty on the bottom of the blades. So no, I do not see the problem.

When it is a zinc shackle in amongst a lot of stainless then that is not the same thing at all. But I have never done it so I do not know. It does not seem right since galvanized rigs are covered in gunk anyway.

 

[Guest]

The use of Galvanized over Stainless has one argument of real merit IMHO .....

Stainless gives no indication of imminent failure.

Galvanized will shows signs of detoriation and wastage - leading to eventual failure. It's why it's a preferred material for keel lifting cables etc.

In case of anchors - I have to admit I have a stainless shackle joining my galvanized Holdfast to galvanized chain ... why ? I do actually disconnect my anchor more than 1x per annum ... and I also do not like the average Galvanized shackle spreading its gunge over me deck !

To those who advocate cutting old shackles out when rusted - I suggest you do it well away from anyones boat ... as no matter how careful you are to brush up after - a speck of metal will be left behind to remind you of that deed when it rusts and stains the deck ...... I know to my cost !!

 

[ccscott49]

Maybe the difference is in the hull material, but there is no way I would use stainless through hull studs to hold my anodes on, mind you I have nothing stainless steel under the water on my boat anyway.

 

[GMac]

From someone who buys 20,000 plus assorted shackles at a time from Italy, China and the Netherlands.

From Italy I buy Stainless steel. Made there and good gear. They also make damn good steel ones as well but only zinc plate them, we just don't do zinc here sadly.

From the Netherlands I buy Green pin Shackles from Van Beest. These are certified hi load and bloody strong but hate shock loads. Yellow pin was mentioned above, there is also orange, blue and many more all made in china. Crosby (Canada) do a red pin but I'm still not 100% sure they are actually made there but at this stage think they probably are. I have not heard of any issues with the chinese or Crosby versions but we stick to the genuine green pin as we do value our customers more than many and the price differance is bugger all.

From china I buy the most. These are mostly your bog standard ones seen in almost every single chandler (and everywhere else) in the entire world. They are OK if used with thought i.e. biggie upsize babe. The quaility of galvanising is crap though as a general rule. They 'wash' the zinc plating to make it look more Hot Dipped, cunning buggers. The loads on these shakles are low and not that reliable. Saying that millions of them are in use right now without any issues.

I also occasionally buy stainless out of china as well but specifically for our on land customers like parks departments and so on. On a boat they tend to pit and look like they are rusting after a wee while. We use the Italian ones on the boats.

Using a SS shackle between your anchor and chain is perfectly fine as long as sized right. The Italian SS are stronger than the chinese steels. We believe the numbers our Italians tells us, we don't believe the chinese numbers unless we verify them here ourselves. Chinese Hot Dipped will be rusty long before non-chinese, we see this frequently with our (and others) chinese and Italian chains.

The meter or so of your anchor chain next to the anchor rusts quicker as it's dragged on the seabed and the rest isn't so the galv wears faster.

And the biggy - why don't we have all the BS, well galved, well made and other shackles we used to have? Simple really, the end user wants cheap. Now they have got it the guys making the good gear can't compete so are shutting down.... gone gone and not coming back. Remember that next time you're in a shop saying "Damn I saw that down the road for 1/2 the price, I'm off there". There is usually a very good reason one is twice the price of the other apart from the accountant in the back room.

Not having a go at anyone, I'm as guilty as most hunting the cheapest option. I've since learnt that the cheapest is often far from the best value for money.

See it at work each day. Punter goes for 'cheapest' and buys chinese, we see them again in 12-18 months. Punter buys Italian and we see them again in 7 + years if at all. The price differance is usually less than 20%. Something to ponder don't you think.

 

[ccscott49]

I picked up a load of Italian stainless shackles, locking carabineers and loads of other stainless stuff when I was there, all stamped and certified and cheap, good stuff. The only place I've found good galvanised shackles, was bogey knights in plymouth and woods at crediton, both ex navy stores, but I may be coming to you for some for my anchor chains. I normally centre punch the exposed ends of the shackle pins and sieze them to stop the coming loose.