Any Preference to which tested anchor shackle to use

I use an ordinary galvanised steel bow shackle which I assume is a bit weaker than the chain. The idea being that if something is going to break I'd prefer to lose the anchor and the shackle and save the chain.
 
Ive just been looking and a grade 80 8MM chain and it has a WLL (working load limit) of about 2000kg
and for a shackle that fits that 8mm chain it needs to be a 10mm pin size shackle, which has a WLL of one ton, so even if you fit a tested shackle the chain will still be stronger.

I stand to be corrected,,, as they say : )
 
Neeves is the authority on high strength shackles. Check out his recent posts, particularly the thread about anchor dragging. Crosby make high tensile shackles with high WLLs, a Google search will find them.

Grade 80 chain is pretty specialised stuff, I know several people who use grade 70 but the vast majority is either grade 30 or 40.
 
Ah right standard chain is 30 or 40 ok,,,,, for some reason I had 70 or 80 in my head

Thanks will check out Crosby,,,


vyv_cox said:
Neeves is the authority on high strength shackles. Check out his recent posts, particularly the thread about anchor dragging. Crosby make high tensile shackles with high WLLs, a Google search will find them.

Grade 80 chain is pretty specialised stuff, I know several people who use grade 70 but the vast majority is either grade 30 or 40.
Click to expand...
 
Thanks Vyv.

I'm puzzled by the reference to G80 chain, its not normally galvanised by HDG as the heat of the galvanising will degrade the strength, by 20%-30% - so I would be cautious of the WLL quoted. I've then looked at the OP's 3 posts and one says a 16mm pin is acceptable (I'm guessing for the anchor??) and the other says the application is 8mm chain - there is a slight contradiction as 8mm chain will take a 10mm pin (note Maggi chain will not take a 7/16" pin - but it has been discussed that maybe the last link could be hammered open to take 7/16" - comments???.

The best shackles come from Peerless and are part of their Peerlift range and are Grade B shackles. They are listed with their G80 and G100 lifting components (not to be mistaken for their confusingly Grade A shackles, also Peerlift in their marine section!!). I simply do not know how you access them in the UK but Peerless are now selling metric marine chain out of Germany (I think out of their new parent company office, Kito) - so contact their international sales, in America, and you might make progress. Campbell and Crosby also make Grade B shackles and Crosby G209A shackles are available from Tecni Lift in the UK (but there are other UK suppliers - I'm too far away to recall them:(. These shackles cost peanuts. :) Peerlift make from tiny to large, both Campbell's and Crosby's smallest Grade B is a 3/8" (7/16" pin)

Grade B shackles - as an example - a 3/8" Grade B has a WLL of 2t and (depends on the manufacturer) a Min Break Strength of 10t-12t. Grade A shackles, like Van Beests Green Pin for a 3/8" shackle have a WLL of 1t and a MBS of 6t. Most shackle makers degrade strength by 50% if shackles are to be loaded at 90 degrees.

Bow shackles, bow through shank, offer a better chance of articulation - achieving that straight line pull.

Shackle pins need to be secured, monel wire is one option. Vyv has options on his website (and I use the same Loctite as Vyv recommends).

The big problem with high tensile chain, galvanised G70 being the most common (and available from Maggi/Jimmy Green), is that there are not compatibly strong connectors. A Grade B shackle of a sensible strength will simply not fit into a metric link. The historic option was to weld larger links onto the chain. This leads to all sorts of questions, who welds the links, are the welds tested, if the welds are done by a subcontractor (who is, say, reliable) how do you have these extra links galvanised. Maggi (and I think Peerless in America) have added the extra links (to order) and included the chain with big extra links as part of the galvanising - but this then becomes a special order with cost implications. In America its not such a big issue as imperial chain has bigger links (a 5/16" chain has a bigger link (hole) than its 8mm equivalent). Maggi are now offering galvanised connectors, check their website. These are G100 Rud, omega shaped, connectors. They are expensive (Stg70 for 8mm) and enormous, so check your bow roller for size. No specification is quoted (and galvanising G100 is unusual, to say the least), but Maggi says strengths are adequate. The pin in the connector is secured by a hammered in lock pin. I suspect the only way to detach the anchor will be to cut the connector off (I don't know how easy that will be (they really are large). I will be testing a 8mm version of Maggi's gal Rud connector in the forseeable future (my schedule has suffered a 4 week delay). Maggi's connectors will need to change as Rud have discontinued the omega shaped connectors for a new design - to the same Rud specification. I checked, Rud do not endorse galvanising G100. However I assume (and assumptions can be wildly wrong) that Maggi accept that there will be a strength degradation from the heat of galvanising but being so strong to start with G100 vs the chain at G70 - the resultant strength is still adequate (I'd like to see some data).

Commonly you then have G70 chain with big links welded on. These then take the appropriately sized shackle that fits the shank of the anchor. Maggi's option is chain, their omega shaped connectors, which take an appropriately sized shackle (there is plenty of room for the pin) and the shackle (bow through shank) fits the anchor.

Normally the chain is the weak link, everything else is stronger.

Caution needs to be taken when trying to fit all these various components together, shackle pins, chain holes etc do vary - so you need to check that each component actually does fit - cut a link off and take/send it before you buy the shackles etc.

Colin if you can clarify exactly what you are trying to achieve - help could be more focussed.

Jonathan
 
Artic Warrior said:
even if you fit a tested shackle the chain will still be stronger.
Click to expand...

My 8mm chain has a break load of 4000kg, and the shackle is 6000kg. The shackle also had to be very narrow to fit through my bow roller, so finding it wasn't straightforward, but they are available. It's a stainless shackle with a countersunk pin, again to fit through my narrow bow fitting.

(Note I'm working with break loads here rather than WLL, as different industries apply different safety factors whereas breaking is breaking.)

Pete
 
I'm twitchy about stainless shackles.

I tested a stainless bow shackle with a recessed pin, I think the break load was specified at, a strange, 4.75t. it failed at less than 4t. Failure was due to gross distortion with the recessed head pulling through the eye but the thread had almost pulled out of the other eye. The bow had stretched. So if you overload the shackle you will certainly see it! I have seen the same sort of failure with unrated galvanised shackles, pin simply pulling out of the thread and gross distortion of the bow.

The Grade B shackles I have tested, and I have tested a number now, show little distortion (in comparison to stainless) and shear where the pin enters the thread.

HT stainless shackles appear to have disappeared from Witchsrd's catalogue (or had when we looked about 1 months ago). Vyv might have more upto date information.

Note the cautionary comment - in the unlikely event the shackle is side loaded the break strength is halved.

Metric chain, G30 and G40 has a safety factor of 4. Maggi's G70 has a safety factor of 5 (I recall). Lifting shackles commonly have a safety factor of 6 but Crosby use 4.5 for their Grade B. Stainless shackles have a whole range of safety factors - you would need to check with each manufacturer.

Jonathan
 
FWIW, I use one of these, 80 grade, BS higher than the chain and they easily go through the link

16-Maglia-giunzione-connessione.jpg


After having tried all sorts of mixtures of shackles (coloured pins, etc), swivels, connectors etc, this piece solved all my problems: runs smoothly through the bow roller cheeks, does not remain twisted against the shank no matter what direction of pull, it's short enough as I have the windlass very near to the roller, etc etc.
The boat is used for training purposes we often anchor up and down several times a day, three years so far and it has just begun to very lightly rust. Cost 8-9 euro at fishermen shops.
 
Good tip Roberto, and jogs my memory. A number of people use these devices, sometimes called hammerlocks (as the HT pin is hammered in). There are many manufacturers, Van Beest, Rud, Peerless, Gunnebo to name but a few (lots made in China). They are readily available from lifting tackle suppliers. I have seen galvanised versions but only in larger sizes, far too big for us (and I have no idea who supplies nor what sort of strength they achieve). I have seen them used on large commercial fishing boats (and other items from the lifting industry). But I do not know how long they last.

The big fears are corrosion and how strong the pin is, its key to strength, after it has both corroded and been eroded through abrasion. The pins are very thin, compared to any other pin 'we' use. The other down side (not a massive issue) is that they are difficult to disassemble if you need to take the anchor off. I suspect the pin locks in, sand, corrosion, and needs hammered our or the whole cut off.

But a number comment on successful use.

In the fullness of time I have intended to test them after leaving them on the seabed to abrade and corrode - but they have not been a top priority.

They, like Maggi's connecting links, illustrate that there are options outside the conventional shackle. If you check Van Beests catalogue you will find they make something they call an Omega link, same design as that from Maggi, but for strength much smaller and neater. Other companies making for the lifting industry have different designs for connection, or shortening 2 chains, there are quite a few options - in time we might find out which is best.

The nice thing about lifting components is that they match. Buy a G80 chain and for that size you can buy various design of connectors and hooks all of which match in size, so they all fit, and they match in strength. Its worth making a visit to a lifting tackle retailer - it might spark an idea and their harnesses make an excellent harness for anyone doing a lot of mast work.

Jonathan
 
China is a common source of Grade A shackles, lots of them here in Oz. That's a 3/8" shackle with a 1t WLL and 6t min break. They are about half the strength of a Grade B. I have only tested a few Grade A shackles from China and they meet and exceed specification. But in many cases I have no idea where they are actually made. What I have noticed is that some of them have the same brand name but are different, the embossed script is different. So I think there are some common and reputable names and everyone, and I think there are lots of manufacturers, is copying.

CMP, of Rocna and Vulcan, make chain under the Titan brand name. I have only tested G30, it easily exceeds specification for strength but has, along with many suppliers, galvanising that might be prone to flaking (Vyv might have a test for gal on his website - but its cut, twist and look to see if the gal flakes). CMP also supply Titan shackles both Grade A, yellow pin, and Grade B, black pin. The, one, yellow pin broke at 8t vs the spec of 6t but the, one, black pin I tested which should have been better than 10t broke at 8t. One shackle is not statistically sound, in fact one test has no statistical relevance but though they cost peanuts testing, say, 5 or more from different batches, - the costs add up (as there is the cost of testing as well). Note Peerless, Campbell and Crosby were adequate (so its not a function of testing). I know of 2 other companies in Oz selling Titan shackles (from a source different to CMP, different embossing). I have another CMP Titan shackle, black pin, Grade B, 3/8th", to test.

Currently for Grade B I would stick with Crosby (or Peerless or Campbell - if you can get them).

One difference between stainless and gal shackles is the length of the pin, stainless have longer pins, they are thus more prone to being loaded - not in a straight line.

Jonathan
 
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Many years ago I used to test galvanising adhesion on steel sheet used for industrial cladding. The British Standard test, I certainly don't remember its number, is a 180 degree bend back over itself, which we simply did by bending it 90 degrees in a vice, then continuing the bend by squeezing the two ends together. Galvanising should take this treatment without flaking. My chain test, cutting a link on the side opposite to the weld, then bending the link laterally though 90 degrees, has not yet been recognised by a Standards Institute (!) but it gave a very useful guide to galvanising adhesion and to the quality of the weld, subsequently backed up by tensile testing.

I used one of those connecting link shackles many years ago and found it to rust quite badly, although it was not used regularly and would have benefited from fresh water washing. It suffers from the same problem as countersunk shackles, i.e. cannot be moused, but Loctite seems to be the answer.
 
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