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Old 21-03-2006, 19:01   #1
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G70 or G7 Galvanized Transport Chain Supplier?

In the process of upgrading my ground tackle and am searching for a supplier of GALVANIZED G7 or G70 transport chain.

Have searched high and low on the web and though this type of chain is readily available, have only found it in a finish called "yellow diachromate" which is not suitable for marine use.

Thanks,
Karl
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Old 21-03-2006, 19:43   #2
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Galvanising is just a generic name for the bath anodising process. "Yellow dichromate" (probably sodium dichromate) is just a material that can be used for galvanising. In my job I have specified sodium dichromate hard anodising for marine applications (specifically with Aluminium alloys such as 6061-T6).

If you particularly want G7 or G70, you could try talking directly with a galvanising facility - they should be able to do most any galvanising or anodising to your requirements.
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Old 21-03-2006, 20:01   #3
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Did you try www.1st-chainsupply.com?
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Old 21-03-2006, 20:41   #4
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Why G7?

It is very very very unusual to find a G7 galvanised due to em-brittlement and strength loss issues.

G7 transport chain is the yellow zinc one. If you galvanise this you end up with, all going well, a G5 or done by someone not very very skilled, a pile of metal shapes.

There are only 2 manufacturers we know of who have galv chain with strengths close to G7. One is Maggi Catene in Italy and the other is a specialist manufacturer in Sweden who will not deal with the public.

The question still begs Why a G7?. It will be way stronger than the anchor will ever hold, the winch hold, the cleat on the deck as well probably and cost a lot.

We do both the G7's mentioned above and it appears to be a US only thing where you get a big boat put on the biggest anchor that will fit and the smallest chain possible. Then 'cruise' from marina to marina.

A system like this is just both very strange, quite fragile and costs a lot more than a perfectly adequate system.

If you have been told a G7 is a lot lighter than an equivalant sized G30 then you have just fallen for an April 1st gag.

If you do galvanise a G7 make sure you load test it afterwards just to make sure the galvanisers did not 'over-cook' it. We have seen this happen more than once and with scary results.
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Old 21-03-2006, 22:12   #5
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Gmac,

Thanks for the reply. I was unaware of the metallurgical challenges in manufacturing a galvanized G70 quality chain.

You ask "Why a G7" chain. The simple answer is WEIGHT.

The boat is now equipped with 50 feet of 3/8ths G4 chain on the main rode and a 15 foot section on the second, both spliced to 3/4" nylon.

I'm swapping the main rode to all chain and was hoping to make the switch to possibly a 5/16ths G70 grade (4700lb WLL) in lieu of the current 3/8ths G40 (5400lb WLL). Doing so, I would realize a loss of approx 700 lbs of WLL but would save over 150 lbs in just this one rode.

The boat is 37 foot, of a low windage design but dry weights at 27,500 lbs. I like the lower price and reduction of weight of 5/16ths G40 versus 3/8ths G40 but I'm not confident the 5/16ths is up to the task of holding comfortably through a strong blow.
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Old 22-03-2006, 12:47   #6
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You're not alone with the galvanising thing, there are a few hidden traps. Things get up to 600 odd degrees C which does play with some metals.

One rule we quite like which seems to fit well and is reasonable is the US Coast Guards that says;

The WLL of your rode wants to be 1/8 of your displacement.

This is approx. 3400# on your boat. Acco G40 5/16" has a WLL of 3900#. This fits quite nicely.

While Acco run smaller WLL 'margins' than most others they are a good respected manufacturer.

The Acco 5/16 chain is the same as our 9mm which is used a lot for vessels in the 33-40ft range crusing the Pacific with no problems.

We sell 100,000's of mts of chain a year and can say with confidence chain failure is very very rare. I'm talking non-chinese made chains here obviously.

With a break load in the 10,000# area I would suspect a few other things will let go well before your chain in a big nasty, like your anchor and definatly winch (but you're not hanging off that anyway are you :-) )

Do the G40 5/16" thing. Save weight and yet more $$'s. Nice.
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Old 23-03-2006, 05:52   #7
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Gmac is not quite correct in his depiction of most American sailors.

Instead of "where you get a big boat put on the biggest anchor that will fit and the smallest chain possible. Then 'cruise' from marina to marina", it would be more accurate to say we get the biggest boat possible, put on the smallest of anchors with the shortest length of chain, and then mostly stay put in our own marina. <g>

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Old 23-03-2006, 14:42   #8
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G70 Zn chromate chain isn't suitable for marine use? I heard the passport 70 chain was DOT required because it could withstand the road salt. Would one of the knowlegeable people be willing to explain some of the finer points of chain? TIA
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Old 24-03-2006, 13:53   #9
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The yellow zinc has become a bit of a 'defacto' standard thing to do with transport chains.

The zinc just gives some resistance to weather, road grunge, rust etc. It is more like a etch primer than a 'coating' like hot dip galv or some other types of zinc coatings.

High grade chains i.e. g60 and up don't rust like lower grades anyway. Lower the grade to more rust is an issue. High grade will rust but being a lot 'harder' it is more just a surface rust than the one that gets right into the chain. Whatever you use will still make a mess of you boat.

Yellow zinc if used on a boat it would rust up quite quickly.

Euro Cruiser - yeah I forgot the mention 'short' lengths of chain, Thanks :-). I don't know about smallest anchor, most I've seen have been on the larger size. The odd one you could wack a small outboard on and use as your dink :-)

We have one here at the moment. 102ft yacht, 3/8" chain and 180kg anchors, big sexy stainless Mansons. Hope they don't have to rely on it at any stage.

Strangly Canadians seem to work more like us. So close to the US and yet so differant, bit like Aussies and NZers :-) Whats all that about??

I know your average Aussie secrectly wants to be a NZer (ducking for cover about now) so they can be good at rugby, yachting, sheep shearing (thats haircuts not group sex :-) ) and things like that. Canadian do or don't want to be Americans or the other way around??

sail safe everyone
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Old 24-03-2006, 14:54   #10
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GMac Thank you again for taking the time to explain the difference.


Jim
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