anchor connectors

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chuzzlewit

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Alarming accounts of failing anchor swivel connectors prompted me to look at mine. It appears OK. On one side is stamped 'KONG ITALY Brevettato' and on the other 'K INOX AISI 316 SWL Kg. 1250'
Is this a reputable make and is it suitable for a 35' sailing boat?
 
Agree. Kong is a good make.

It's always a good sign if a manufacturer puts their name and technical details on a product especially a small item like this. You wouldn't find this on a cheap 'copy'.
 
Kong is a good make. 1250 kg is somewhat less than the working load of 10mm (I just happened to look it up today in the chandlers and it is around 3000 kg). I've just bought a Plastimo connector with a SWL of about 10% more than the chain. Personally, I think you should rate the connector higher than the chain as the connector will wear especially if it is a swivel as wear leads to reduced strength.

Inox is stainless steel and it will be fine unless it ends up underwater without oxygen - stainless corrodes rapidly in the presence of an electrolyte in the absence of O2. So it isn't good in mud for long periods where the conditions can be anaerobic. As a guide, if you are using it to anchor for days or weeks at a time, you should be fine, but don't use it for moorings or if it will be down for many months at a time but if you suspect anaerobic conditions, don't use it.

AISI 316 is the correct grade of stainless steel for a marine environment.
 
10mm short link chain to DIN766 has a working load limit of 1250kg, a proof force of 32 kN and a breaking force of 50kN and don't let anyone tell you different.
 
[ QUOTE ]
10mm short link chain to DIN766 has a working load limit of 1250kg, a proof force of 32 kN and a breaking force of 50kN and don't let anyone tell you different.

[/ QUOTE ]Assuming you have have checked those figures, could be that the figure we looked up in the chandlery today was the "proof force". What is the difference between 'Working load limit', 'Proof force' and 'breaking force' - i.e. what are the definitions of those terms? Is 'working load limit' the same thing as 'safe working load'?
 
Fitting a stainless connector on our rather old anchor and chain caused incredibly quick corrosion of the end few links of chain.
 
[ QUOTE ]
Fitting a stainless connector on our rather old anchor and chain caused incredibly quick corrosion of the end few links of chain.

[/ QUOTE ]There is not (supposed to be) any electrochemical action of any significance between galvanised steel and 316 stainless steel. When you say 'corrosion', I suppose you do mean 'rust' (i.e. red Iron Oxide)? Galvanising works even when damaged but there comes a time when it gets so thin and patchy that the whole part rapidly rusts. I suspect that it was a coincidence that this happened just after you changed the connector.
 
[ QUOTE ]
Weren't these tested in PBO a short while ago (last 7 months)

[/ QUOTE ]
Yes, and the Kong connectors outperformed all other ones on test by a great margin.

Actually, Kong is a leading mountaneering-equipment manufacturer, so they are accustomed to think in terms of people's lives being - quite literally - dependent on their products, which are all built in-house (no cheap chinese copies, here).
 
I did the testing and wrote the article, which was in YM, not PBO. Not wishing to rewrite the whole thing again, I will only say that I use a Kong swivel.

The main problem with swivels is that in conjunction with certain anchors with flat shanks, e.g. Delta, the load can come on them in bending, as they cannot articulate in the connection point. In this case a shackle may be needed in addition to the swivel. The Kong swivel packaging explains this and gives some data on SWL in this case.
 
Chain and most associated items:

Terms:

WLL (working load limit) is the same as the SWL (safe working load) is the same as MWL (maximum working load)

DL = Destruction load (sometimes can be Deformation Load i.e the load at which it starts to change shape. This is not that common on the everyday stuff)
MDL = Minimum destruction load
Break load = if you can't figure that out stay, in bed /forums/images/graemlins/smile.gif

Proof load = the load applied in the factory test process. This is an actual load applied not calculated or anything.

The WLL is 1/4 of the rated break load.
Proof load is twice the WLL
The Proof load is 1/2 the rated break load
The Break load is 4 times the WLL.

10mm DIN766/A for example has a WLL of 1250kg (12.5kN), a Proof load of 2500kg (24kN) and a rated break load of 5000kg (50kN). A bit naughty there using a 1kN as exactly 1kg when it is not quite but damn close. The 10mm numbers are correct, I sell a 1000mts a week of the stuff. For our American viewers 10mm is close but not quite 3/8" which does have slightly differing numbers obviously. Don't confuse it with Hight Test either which is a grade 40 chain where the DIN is a grade 30. G40 is 25% stronger than G30.

So all chains and most bits associated will have been pulled to twice what the manufacturer says is the WLL. NOTE: there is some variations on this theme when talking other grades and/or applications. Generally these variations will give a greater safety margin, very very rarely be less. 99% of your everyday boating gear runs 4:1 safety margins. Chain is one of the oldest man made products so it's behaviour is pretty well known by now.

Obviously some stuff from the east does not get the same treatment as stuff made in Italy, for example. Many say and think is does but some just does not. This is well known in the industry. No-one I know in this game trusts eastern manufacturers Test Certificates. Not all is crap just most at this stage.

Swivels
Kongs are fine as are 1 or 2 others we know of. Most are crap.

The one below is a 16mm with a listed break load of 10800kg. This is what it looks like after only 4000kg have been applied. I'm willing to bet a large number of cold beers it wouldn't make it to 4500kg.
268a3d53.jpg

The real spooky bit, if the way dodgy break load was not enough, was that the 2 bits of the above 16mm swivel are actually held together with a 12mm bolt.

The one below this, again 16mm, has a SWL of 5000kg. This is what it looked like after having 23000kg applied during a test for a big boat classified under BV.
16mm_swivel_sml.jpg

FYI- this is held together with a 24mm bolt.

The top swivel is made in asia and the bottom one in NZ.

Anyone starting to catch on why some stuff is so much cheaper than some other and still thinking the cheap stuff is the way to go all the time?
 
Opps.. forgot
vyv_cox - there are some universal like the below which sorts out the sideload issue. Or you can just put a few links of chain off your anchor to the swivel then to the main rode.

The 2 on the left
swivel_seclection.jpg
 
Two really fine, useful posts, many thanks. I've copied them to keep in my 'useful bits of info' file.

The side load is an issue for me, having just bought a Delta. It is hard for me to fit a shackle as I have 'ears' either side of my anchor roller to help keep the chain on and I only have 40mm between them. Anyway, despite the accepted wisdom, I don't feel happy about letting the shank of a shackle take the edge of the anchor slot; surely there must be a risk that a small V will appear and cause a stress crack. A fixed round pin held at 90 degrees to the anchor slot feels much more sensible.

Anyway, after Vis's post above I took the Plastimo swivel I'd bought the day before back to the chandler and ordered the Kong - they had a small Kong on a card that gave their tech. details about side loads. I have ordered the 8 -12 mm and the side load is quoted as 2000kg and the straight load 5000 kg approx. At least they do quote side loads.

It seems to me that a 2000kg side load is going to be hard to achieve in practice with a Delta unless the anchor is actually trapped in something like rock or coral or maybe a wreck. Furthermore, I suspect (what do you think?) that a 2000kg side load on the connector slot of a Delta will bend the shank making it no longer a side load! I just cannot see it remaining straight so even if I fit a shackle or other means of achieving a universal joint, the anchor is going to bend long before a problem occurs. This bit is a guess, though, I don't have any metal loading tables and if I did I'd need to re-learn how to use them to calculate bending loads.
 
I think yours must be an earlier design but genuine - the logo and data look OK and I doubt whether a cheap rip-off would have that stamped on it. They are mechanical devices, and the swivel will wear, of course. Presumably they ought to be replaced from time to time.
 
Your swivel looks OK to me, clearly the same design as my Kong. It has a stamped SWL value and, more importantly, the chain load is not applied to the bolt that holds the fitting together. The one shown has the fixed body screwed together with a countersunk screw, which should be assembled with thread-lock.
 
[ QUOTE ]
..more importantly, the chain load is not applied to the bolt that holds the fitting together. The one shown has the fixed body screwed together with a countersunk screw, which should be assembled with thread-lock.

[/ QUOTE ]I can't see what you mean from the photos, could you explain?
 
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