Rocna or Manson Supreme??

[vyv_cox]

Bugel may be a different matter as the design is freely available and anybody can make one, from whatever they like. See my comments about the ones sold by Compass24 - their boat size/displacement table gives values very different from those I was told by a German manufacturer.

So far as strength of steel is concerned, I know that Rocna and Delta shanks are made from high tensile steels. I would suggest that any manufacturer who made a plate shank from low-carbon (= not heat treatable) steel would be asking for trouble, as they could not possibly sustain normal anchoring loads without bending.

On welding, it would be a very careless manufacturer who allowed poorly welded product to go out. Non-destructive testing, certificated welders and increasing QC standards will take care of this issue.

 

[Anonymous]

[ QUOTE ]
So far as strength of steel is concerned, I know that Rocna and Delta shanks are made from high tensile steels.

[/ QUOTE ]
On their website, Rocna say "The Rocna uses mild steel for the fluke and roll-bar."

When I tried to find the figures for my Delta in order to calculate the lateral force issue on the Kong I was unable to find any figures at all. I ended up doing the sums on the basis of the highest YM likely for that class of steel, as a worst-case scenario. Does anyone know what the Delta steel spec is?

Even on that scenario, the Kong should be very, very safe under lateral loading conditions unless the shank becomes trapped well up towards the connector, say trapped in rock. We don't generally anchor on that sort of ground. Even 1.5 tonnes, the max stated lateral load, is greater than many shackles that people would use. It doesn't follow, I suppose, that their quoted load is within the elastic limit....that might explain why DavidS experienced non-elastic deformation without component failure (and continues to use the product).

 

[AncoraLatina]

[ QUOTE ]
Never use a swivel connector directly on the shank of the anchor:
- they don’t turn under load
- they are not designed to support any lateral load

<span style="color:blue"> Not true. The Kong connectors are specified to take a defined lateral load </span>

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Right LEMAIN I should have said, “never uses MOST swivel connectors! The one manufactured by WASI can also take a lateral load...

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no anchor could survive that.

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Not true.. during my (long) experience, I’ve seen a lot of bent shanks on nearly all anchors. Never seen a bent tip on a CQR for example.
If you look at the distance between the tip and the root of the shank on the Supreme, it’s quite long.. Now compare the same distance on the RAYA anchor.. More the distance, more the chance to bend!..

[ QUOTE ]
Rocna's are made in NZ or under license in America.

[/ QUOTE ]
..and now also in China! It seems that the fluke is now cast!..

João

 

[DaveS]

Yes, it's definitely a Kong, the two part design where the load is not taken by the fixing bolt. I can't remember what markings it has, and I won't be near the boat for a couple of weeks. I'll take a picture of it when I can (provided I can find the camera which I carefully put somewhere safe some months ago...)

 

[Anonymous]

[ QUOTE ]
Yes, it's definitely a Kong, the two part design where the load is not taken by the fixing bolt. I can't remember what markings it has, and I won't be near the boat for a couple of weeks. I'll take a picture of it when I can (provided I can find the camera which I carefully put somewhere safe some months ago...)

[/ QUOTE ]A picture would be interesting, especially with some details of the size of the yacht, type of rode, depth, length of rode, weather conditions and bottom type if known. My Kong does not have the lateral or linear SWL marked on the product; that was marked in the catalogue and on the cardboard packing on the blister-pack that it was supplied in.

 

[Anonymous]

[ QUOTE ]

[ QUOTE ]
no anchor could survive that.

[/ QUOTE ]

Not true.. during my (long) experience, I’ve seen a lot of bent shanks on nearly all anchors.

[/ QUOTE ]I phrased that badly. What I mean is that if the anchor is trapped up to the top of the shank and you have a connector with, say, 1.5 tonnes lateral force then unless the torsional force is sufficient to bring the connector back into the direction of pull by bending the shank, then the connector might be the weak link and fail at (in my case) above 1.5 tonnes. If the shank is mild steel then 1.5 tonnes on the end of the connector might produce a moment great enough to twist the shank -- but you'd need to know more about the steel to be able to calculate it. 1.5 tonnes is quite a force, though. As I said above, many shackles will fail below that. Plastimo give the SWL for their shackles in their catalogue -- one of the few that do. That's why I try to buy Plastimo for vital applications such as anchoring.

 

[vyv_cox]

No reputable shackle of above about 6 mm is going to fail at 1.5 tonnes. The SWL of many shackles is the UTS/4 but for some of the rated ones intended for lifting and hoisting (usually the coloured ones, green pin, etc.) it is UTS/6. A yellow pin one that was tested had a SWL of 0.75 tonne but failed at 6.14 tonnes. Most of the stainless steel ones had a UTS that matched or exceeded the UTS of the chain. Almost all of the galvanised shackles were weaker than the chain. The weakest, an 8 mm one, failed at 2.4 tonnes, about 50% of the UTS of 8 mm chain.

(UTS = Ultimate tensile strength)

Probably the strongest shackles you can buy through any marine outlet are the Wichard 17/4 PH ones. The majority of stainless steel shackles are made from a 300 series stainless steel, either forged (more expensive) or cast (cheaper). 300 series SS is austenitic and cannot be hardened by heat treatment. 17/4 PH is a precipitation hardening steel that has equivalent corrosion resistance to a 300 series but can be heat treated for increased strength. Of the two Wichard 10 mm shackles tested, the bow failed at 5.4 tonnes and the 'D' at 6.7 tonnes.

 

[Anonymous]

I don't remember whether the Kong lateral figure is SWL or UTS, or what the failure mode is. Looking at the Kong you'd think that it would bend through 90 degrees before failing to secure the anchor. Regarding the figures for the shackles, the Plastimo ones are rated rather lower than you quote, I think, but don't have figures to hand -- but at least they are specified.

As for other shackles, I have asked several chandlers for coloured pin shackles but few people have ever heard of them so when people recommend using "a shackle" the average yachtie assumes that all they need to do is ask the chandler for a shackle. I wonder how many people here, who connect with a shackle, have any idea of who made it or the SWL? I haven't been able to source the coloured pin shackles in Spain and I haven't seen any in Italy. I think I tried without success in Chichester (Peters).

More importantly, in this context, is the effect of the sharp slot. When shackles are tested (or rated) is this with a sharp edge like a knife in direct contact with the pin? That's what could happen with a shackle on a shank. The stress at a knife edge is tens of thousands of times higher than you will get from a straight flat pull. The more radiused the contact (e.g. a thimble) the greater the area and the lower the stress but anchor slots tend to be sharp. Once you get a region of high stress, you are at risk of getting a stress fracture and this could fail at a far lower load.

The Kong connectors are designed to pull flat -- I can't see that they are likely to present the pin on an edge....but if they did, the connector pin is very much bigger than a typical shackle. If one is going to use a shackle then one ought to buy a branded shackle of defined strength -- and check that the pin will not be 'cut' by the slot.

 

[Goldie]

Colored Pin Shackles at Jimmy Green Marine: http://www.jimmygreen.co.uk/chandlery_pr...oloured_pin.htm

 

[vyv_cox]

That's the one that tested well. In the majority of cases it was the pin or its thread that failed first on galvanised shackles, so there is logic in increasing the pin size.

 

[Pete7]

Richard I don't think you should buy either of those old fashioned designs when you could have the latest idea,

http://www.stealthanchors.com/

Standing by for the barrage /forums/images/graemlins/grin.gif

 

[DaveS]

[ QUOTE ]
A picture would be interesting, especially with some details of the size of the yacht, type of rode, depth, length of rode, weather conditions and bottom type if known.

[/ QUOTE ]

Well, as I said, a photo might take some time to organise, but I will post it when I can. The rest of the details are in the blog reference I quoted (as are some thoughts on setting anchors which might be of interest), but in summary:

Date: 2-3/7/05,
Location: South Basin, Loch Maddy, North Uist,
Boat: Etap 30, about 4 tonne loaded displacement,
Anchor: 16kg Delta,
Rode: 35m of 8mm chain,
Depth: 5m,
Bottom: mud,
Wind speed: F9 gusting 10,
Wind direction: E veering SW veering NW.

 

[Chris_Robb]

Re: BUT IT THIS A MANSON?

[ QUOTE ]
[ QUOTE ]
Does anyone know the spec for the galvanising on the Rocna and Manson?


[/ QUOTE ]

I took these photos recently of a rusty Manson Supreme with a bent tip.

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I am not sure that the anchor show is a Manson - see the picture below, and look at the reinforcing along the tip. You must be careful to make sure that what you say it is, it really is.

Richard also wanted to see how it fitted, so I have added another 2 closeups of it on the bows of a Westerly Oceanlord.

Richard, because it is a tight fit, it need to be pinned in place 1) at the bow roller, and 2) halfway down the shank. This was the standard set up on the Oceanlord, and I had the shank drilled at the right place for the bow fitting.

 

[noelex]

Re: BUT IT THIS A MANSON?

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I am not sure that the anchor show is a Manson - see the picture below, and look at the reinforcing along the tip. You must be careful to make sure that what you say it is, it really is.


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I am 100% sure it is a Manson Supreme. The reinforcing along the tip is exactly the same as the photos of your MS (except yours isn't bent or rusty )

 

[Anonymous]

Re: BUT IT THIS A MANSON?

The label looks much the same, as well.

 

[Anonymous]

Just to recap -- we are talking about damage to the Kong connector apparently due to lateral force? If the bottom was mud, and the connector deformed, then we are wondering what happened? Could be that there was something like a concrete mooring block or rock down there preventing the anchor from turning? It will be interesting to see the pic of the connector.

 

[machurley22]

Re: BUT IT THIS A MANSON?

Do you have any idea how the Manson got into this state?

I see you are a Rocna man. /forums/images/graemlins/smile.gif

 

[noelex]

Re: BUT IT THIS A MANSON?

[ QUOTE ]
Do you have any idea how the Manson got into this state?

I see you are a Rocna man. /forums/images/graemlins/smile.gif

[/ QUOTE ]
No no idea. The anchor was on a charter yacht pulled up on the hard for the winter.
I recently purchased a Rocna anchor, so I guess you would say I am a Rocna man, but if the Rocna was not available I would have purchased the Manson Supreme which I think is also a very good anchor. My only connection with Rocna is that I bought one of their anchors.
When I saw the state of the Manson Supreme in the photos I took, I was, However, very glad I had chosen the Rocna above the Manson. There was a similar sized Rocna, in perfect condition, on a boat only a few meters away. This doesn't mean much as the anchor ages and use could have been vastly different, but it did provide a stark contrast.
I know people, for some reason, get very passionate about anchors, but I am only reporting honest findings. These anchors are relatively new and I think durability concerns are valid.

 

[Anonymous]

Re: BUT IT THIS A MANSON?

I think you're right. Some anchors have been designed and built in one place then the production farmed-out. Not a problem if the company has extensive contract manufacturing experience but the contract mfr market is one of the most aggressive and cut-throat in the world. Quality of materials, assembly, plating, finish are all big issues for anchors. You need a very experienced QA rep to ensure that you are getting good product. Many anchors are made in places you last heard of in a school geography lesson yet you pay prices that should allow them to be made by craftsmen in Sheffield.

 

[Chris_Robb]

Re: BUT IT THIS A MANSON?

[ QUOTE ]
[ QUOTE ]

I am not sure that the anchor show is a Manson - see the picture below, and look at the reinforcing along the tip. You must be careful to make sure that what you say it is, it really is.


[/ QUOTE ]
I am 100% sure it is a Manson Supreme. The reinforcing along the tip is exactly the same as the photos of your MS (except yours isn't bent or rusty )

[/ QUOTE ]

In looking at your photos, they don't seem to show the same tip shape. Looking at the right hand one, it is difficult to see the thickening at the forward end, but this may be the angle, light etc. Perhaps this was an early version, or even a copy. Looking at the label, I have to disagree with Lemain - I really don't think it looks like the original.

If it is a copy that has got a mild steel fluke are, then the bending is perhaps to be expected. Perhaps that is why some copies are cheaper. This is especially prevelant amounts CQR's - where some are Cast shanks, and not forged.

As for the galvanising, I really do not understand how an anchor that was properly galvanised at birth, and Mansons are, could end up like that.

I still reckon that this is not a Manson, but a cheap copy! Who ever heard of a charter company paying for an expensive anchor - which Mansons are!!!

By the way - Sorry to impute your integrity on this matter, I was not, is not intended.