Bolt type pin shackles

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Boo2

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Hi,

I am thinking of using galvanised bolt type pin shackles on my mooring see here, and I wondered whether there is any possible corrosion issue with using stainless split pins to secure in the marine environment ? Obviously I don't want to give the galvanising a harder time than I need to but equally I don't know a source for galvanised split pins either.

Does anyone happen to know about this and whether the shackles in the link are supplied with galvanised pins ? Or is there no issue with this in practice ?

Thanks,

Boo2
 
In galvanic combinations the issue is not only with which is anodic compared with the other, but also their relative sizes. The example we use in training is a steel rivet in an aluminium plate and an aluminium one in a steel plate. The aluminium rivet will corrode rapidly as it has a big area of steel driving the reaction. In the reverse case the aluminium plate will corrode slowly because the rivet is so much smaller. I suspect that monel, stainless or brass wires/split pins would fall into a similar situation, so the steel shackle would not corrode appreciably. I did see a letter or article recently in which a shackle fitted with a monel mousing wire corroded quite badly. The writer of the piece believed the monel wire to be the culprit but it was my opinion that the pin and shackle body were probably of different compositions and that was the cause.
 
Colvic Watson said:
Use Monel wire instead. Some use cable ties but most aren't UV resistant or that strong.
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vyv_cox said:
In galvanic combinations the issue is not only with which is anodic compared with the other, but also their relative sizes. The example we use in training is a steel rivet in an aluminium plate and an aluminium one in a steel plate. The aluminium rivet will corrode rapidly as it has a big area of steel driving the reaction. In the reverse case the aluminium plate will corrode slowly because the rivet is so much smaller. I suspect that monel, stainless or brass wires/split pins would fall into a similar situation, so the steel shackle would not corrode appreciably. I did see a letter or article recently in which a shackle fitted with a monel mousing wire corroded quite badly. The writer of the piece believed the monel wire to be the culprit but it was my opinion that the pin and shackle body were probably of different compositions and that was the cause.
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Interesting. I am categorically not going to use monel wire because that is what I used the time before when Sunrunner went adrift and the shackle came undone anyway. I got the advice to use cable ties from the Langstone Harbour people who use them themselves and I also took your advice, Vyv, to use threadlock.

If I can't find a source of galvanised pins for the safety pin shackles then I will just use ordinary shackles. I asked similar questions of Tecni-lift and got a reply as follows :

Re. your questions, we have answered to the best of our technical knowledge:

1. Are they suitable for use in the marine environment ?
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The shackle body is galvanised steel and the pin is red painted alloy steel. Both have a good degree of corrosion resistance and are frequently used offshore for lifting applications. The shackle will rust however with long term exposure to a saline environment and would require regular inspection and cleaning to ensure that corrosion is minimised.

2. Are split pins supplied with the shackles and if not what size is required for what shackle size ?
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The correct sized zinc plated split pins are supplied with the G-2130 shackles (1 pin per shackle).

3. Are galvanised split pins available and if not what are the consequences for corrosion on using stainless ones ?
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Zinc plated split pins are supplied with the G-2130 shackles and these offer a small degree of corrosion resistance - better suited for on-shore applications. The standard split pins are not galvanized - they are zinc plated which is not as resistant to corrosion. Stainless split spins would offer good corrosion resistance but would not be compatible with the shackle pin material in a marine environment (the saline environment would speed up corrosion between the two materials). The stainless split pins would be acceptable in an on-shore application.

We do stock stainless safety shackles if you are interested. We can supply them tested or untested and they are dimensionally the same as G-2130 type shackles.
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Can anyone tell me the difference between galvanised and zinc-plated in this context ? Also, does anyone know where I can get galvanised split pins suited to the marine environment ? I don't want to introduce stainless into the system at all : as I said if I can't use safety pin shackles I will just carry on as before with ordinay shackles, threadlock and cable ties.

Thanks,

Boo2
 
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Boo, you may be asking the wrong question of the suppliers. Whilst use in a mooring is in a marine environment, the fairly careful wording of their reply suggests to me that they are considering their use in lifting gear which would not include long periods of immersion in sea water. I'd suggest asking them if they consider the shackles suitable for use as part of a mooring.
My understanding of the difference between zinc plated and galvanised lies in the process used. Zinc plating is done by electro plating a very thin layer of zinc on to the metal, whilst galvanising is where the metal is dipped into molten zinc, which gives a much thicker coating of zinc. No doubt someone else will be along shortly to confirm or deny my understanding.......
 
I have found mousing with monel wire or cable ties to be hit and miss on a swinging mooring, above water, due to the considerable agitation in certain sea states. Though I have never lost the boat, regular eyeballing has shown either one or the other to be broken or missing.

I feel you are on the right lines with the bolt up type with split pins, and personally would not now use anything else.

I think the supplier is suggesting that the shackles are hot dipped and the split pins are electroplated. As they suggest, the electroplated items will quickly rust in seawater. I have never found this matters and would even use a mild steel pin in this application. Just insert with waterproof grease and inspect every couple of months. However, for peace of mind use a stainless pin grease it and fully turn back the legs. In terms of the overall material in the pin any additional corrosion will never lead to failure.

Just my view but it is from experience, hard won.
 
What you might be looking for is called a Pin & Forelock shackle . A split pin is to weedy for moorings, s/s split pins tend to weld themselves in the hole.
 
I have always considered mooring shackles to be for one use only, so there is another option available so long as the pin extends beyond the nut. Locktite on the threads not only locks the thread, but helps minimise ingress of water between the surfaces. Mousing can be done with galvanised fencing wire, although it should be checked and replaced on a regular basis. Once made up, hammer the end of the pin so as to upset the profile so that it can no longer be withdrawn - belt, braces and sewn to the jacket!

Rob.
 
When I had a mooring, I was always told to never use a galvanised shackle, but rather a black metal one from an agricultural merchant. It certainly seemed to work and the black metal shackles outlived the galvanised ones.
 
oldsalt said:
When I had a mooring, I was always told to never use a galvanised shackle, but rather a black metal one from an agricultural merchant. It certainly seemed to work and the black metal shackles outlived the galvanised ones.
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I would love to know exactly what these are. I have been given the same story in the past, regarding chain, shackles and other things. Have never managed to find exactly what they are, other than maybe my guess wrought iron. Some types have better corrosion resistance.
 
If you are not happy with locking the nut on the shackles with a split pin you could add a second nut and lock the both together or replace the nut with a nylock or aerotighte locknut.

You could also use a normal shackle (threaded one side ) and replace the pin with a galvanized bolt with the full diameter the same length as the full length of the existing pin then add a nut to lock the bolt in to the shackle body.

I have also made shackles with an internal threaded pin with setscrews screwed from either end that locks the pin so it cannot cone undun.
 
Boo2 said:
Hi,

I am thinking of using galvanised bolt type pin shackles on my mooring see here, and I wondered whether there is any possible corrosion issue with using stainless split pins to secure in the marine environment ? Obviously I don't want to give the galvanising a harder time than I need to but equally I don't know a source for galvanised split pins either.

Does anyone happen to know about this and whether the shackles in the link are supplied with galvanised pins ? Or is there no issue with this in practice ?

Thanks,

Boo2
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Your boat used to be moored in front of mine in Pwllheli on the pile moorings. I used to use bog std 5/8" "farm" shackles. Zinc plated, siezed with monel. One on each line so there were two forward and two aft. They were cheap as chips and I used them on a one season use only basis. The zinc came off in a matter of weeks but the thickness of the material is what I based the strength on. I used to slather grease on the threads and tighten them with a ten inch movie spanner. I never had an issue with them, they stayed tight, corroded a bit but there was enough material in them to keep them strong enough for a season. I was on the piles for about 6 years and never worried about them.
S
 
vyv_cox said:
I would love to know exactly what these are. I have been given the same story in the past, regarding chain, shackles and other things. Have never managed to find exactly what they are, other than maybe my guess wrought iron. Some types have better corrosion resistance.
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I used to buy them from Morgans in Oswestry.
Stu
 
We often bed our shackle pins in stockholme Tar ( obtainable from Horse tack shops & used for horse hooves)
We also use very thick cable ties.
We often find old shackles have worn around the pin & the bit of thread coated in tar is in good nick. if we do not use tar we often find that the thread on sub standard shackles fails so even if the shackle is a big one the relatively smaller thread area fails quickly making the shackle useless
The galvanised shackle we use are EU tested & marked as such. We have used non galvanised & they last just as long but I do not sell many because buyers think galvanised must be better. However, the galvanising wears where the chain rubs so it does not last longer. Make sure that you do not buy low grade farm shackles.
 
I can not say if the lifting shackles the OP linked to are suitable, but Van Beest Green-pin shackles with bolt and stainless locking pin are most certainly used for moorings. Gael Force in Inverness - who have oddles of experience and an excellent reputation and name to protect - designed and supplied my riser assembly in Plockton, and these use Green=pin shackles. I also went out on the local mooring service / dive boat and watched what they did on other peoples moorings: use green pin shackles with stainless split pins.
 
Daydream believer said:
We often bed our shackle pins in stockholme Tar ( obtainable from Horse tack shops & used for horse hooves)
We also use very thick cable ties.
We often find old shackles have worn around the pin & the bit of thread coated in tar is in good nick. if we do not use tar we often find that the thread on sub standard shackles fails so even if the shackle is a big one the relatively smaller thread area fails quickly making the shackle useless
The galvanised shackle we use are EU tested & marked as such. We have used non galvanised & they last just as long but I do not sell many because buyers think galvanised must be better. However, the galvanising wears where the chain rubs so it does not last longer. Make sure that you do not buy low grade farm shackles.
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When I was in Africa in the early 80s I was with an American civil engineer watching them building hi rise buildings, scabby cement jobs etc. I said to him why dont they fall down, he said its the steel, they grossly over size it and it keeps them safe.
Its the same as the farm shackles I used to use, grossly over size for the job, change every year, not a prob!
S
 
I think it best to use ordinary shackles ie witha pin that screws into the shackle body. When you tighten it up the pin can not rotate in the body. If you used a shackle type with a bolt and nut or even just a pin you will get movement of the pin in the body of the shackle. This movement will quickly remove galvanising and also quickly rmeove any protective rust that occurs on the faying surfaces. The result will be wear or enlargement of the pin holes. There is quite alot of tendency to rotate the pin in the constant jerking of a mooring hence the need to mouse a screw in pin but also the need to tighten the pin as much as possible to avoid any rotation. (also use thread locking goo) That then leaves wear on the pin itself and the bale of the shackle where at least it is easily seen. As said use the biggest shackle you can fit in, forget galvanising or high strengt, youh just need bulk metal at the wear surfaces. good luck olewill
 
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