Anchors - Bigger is Better ?

[JonJo]

Trying to keep all of this positive and not to be accused of reiteration, again

(Some) Members are not convinced by manufacturers data.

(Some) Members buy bigger anchors.

(Some) Members swear by Crosby shackles

There is some consensus that snatch, dynamic loads are an issue.

Can anyone quote the sort of snatch or dynamic loads they would look their ground tackle to resist and what sort of safety margin they think they are building in?

If you are going for 'bigger is better' you must have some concept of orders of magnitude, or you would not be quite so vociferous.

I'm thinking in orders of whole tons and safety margins of 2, 3 or 4 times whatever. In order to comment you need to add detail of your anchor, type and size and size of yacht, maybe length and weight - otherwise its all a bit of a waste of time.

If you think for a 50' yacht that the worst case scenraio is a 1t snatch load - I frankly think going 'bigger is better' looks questionable - so what's the story?

[DumnMad]

Congo: This quote from the Bisalloy website;

"It can be seen in figure 6.10 that for butt welds when R = -1 (equal tension and compression) the fatigue strength of BISPLATE® 80 is reduced by more than half its base material value (fig 6.9) and to substantially the same values of AS3678-Grade 250. This indicates that there is very little advantage in using high strength steels under such loading condition. On the other hand, for conditions where R is positive, i.e. high static loads with a superimposed pulsating load, there is a distinct advantage in the use of high strength steels."

Not all load conditions will give you the results you want!

[JonJo]

Listen to experienced cruisers?

A couple of days ago I gave a list of experienced cruisers, so experienced they had all won awards for their exploits - and they all used CQRs

Here is another one:

John Simpson, established the Lanzarotte to Caribbean, Christmas Carib Rally. Did the ARC last year, has 20,000nm under his belt in his current yacht a Warrior 40. Ought to know something about anchors? (but) carries a 45lb CQR. Warrior 40, 16t, 40'.

[JonJo]

Originally Posted by DumnMad

Congo: This quote from the Bisalloy website;

"It can be seen in figure 6.10 that for butt welds when R = -1 (equal tension and compression) the fatigue strength of BISPLATE® 80 is reduced by more than half its base material value (fig 6.9) and to substantially the same values of AS3678-Grade 250. This indicates that there is very little advantage in using high strength steels under such loading condition. On the other hand, for conditions where R is positive, i.e. high static loads with a superimposed pulsating load, there is a distinct advantage in the use of high strength steels."

Not all load conditions will give you the results you want!

Maybe you need to check the product first as Excels are not butt welded.

[congo]

Noelex wrote:

Rex you are far more of an expert on anchor proof load tests than me, but I don't really see your point.
This is a photo of the Rocna and Super sarca attachment points. There does not look to be much difference in the distance from the tip to the attachment point, at least to my eyes.

The Rocna video shows a 55kg anchor that withstands a 17 Tonne force without perminant deformation.
Your website claims a a 185 kg (over 3 times bigger) Super Sarca anchor withstanding a 10 Tonne force.

We consumers are a bit jaded by anchor manufacturers promotional videos so I am not sure it means much.
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Gee Noelex I am going to bottle your opening remark, and thanks for taking another look at the proof testing procedure,

The correct method of proof testing is as what you see with the big Sarca, 185 KG, 10 ton is the basic load required, on our test certs show it was taken to more than twice that, no point in a destruction test to prove constructional design. we have been through all of that over twenty years and destroyed many anchors finding the yield failing points.

Now if we moved the anchor strap back until it is square with base of the shank as is the Rocna video clearly it would then be a lateral pull, not vertical, you would probably max out that machine at around 30 ton and do no damage at all to the Super Sarca, leave the strap where it is in the verticle and max out that machine you would be getting some movement for sure between the end of the shank and the end of the fluke toe.

This vertical test gives you max leverage the big destroyer, more importantly it gives you shank strength seperation of weld strength and just as important the fluke plate.

The critical meauserment for prmanent set is not taken along the shank as is the Rocna test. Before our anchors are tested the distance from under the front of the shank down to the front of the toe is recorded, after releasing the proof load the measurment is re taken to record -prove any deformation.

Really no different to the link John Kettelwell posted. It is wrong to put Lioyds and Rhina on a video that they would certainly not support as a proof test, the loads they are giving you are totoaly false in the spirit of what proof testing is all about, to verify my claims post Rhina AND LlOYDS THE VIDEO AND WATCH THE FEATHERS FLY.

Missus is not arround so excuse the spelling.

Regards Rex.

[congo]

Like Isaid Dumad, jump in our factory for a week and I will educate you.

Regards Rex.

[Shanaly]

Some here anchoring in coral weld a rounded shoe to the bottom of the pointy end of a plough. Also they add lead. Holding is great anywhere, and it doesn't cut and 'plough through' coral.

[DumnMad]

Read the Bisalloy link JonJo. Note they take care to compare strength with Gr250 and not Gr500. Note also its welding in general that affects the parent metal.

I'm picking the anchor manufacturers have designed around this susceptibility making the failure point away from the weld but they are wrong to make big claims about steel superiority.

http://www.bisalloy.com.au/applicati...20bisplate.pdf

[congo]

Dumad you are sounding like our Prime Minister, promissing a budget then cant deliver, as I have said we have been manufacturing anchors for twenty years under the watch full eye of the marine authories, never had a shank brake or a shank bend at the weld.

Isn't it funny how when I come on to defend a comment the whole thread lites up, must be good for buisness.

Regards Rex.

[JonJo]

Noelex,

I might be with you on this one.

The Proof tests are not designed for our anchors. They were established donkey's years ago to test large commercial anchors (think of any 100,000t ocean going vessel). They really are not focussed toward 'our' anchors. However no-one least of all the Classification Societies have come up with a test method that suits what we use. But do not knock the CS, its our industry - we pay for the tests (unless you think Manson pay from the goodness of their hearts) - its upto us to come up with something and make sufficient noise to have someone take notice (unless you think it not necessary).

Proof testing tests strength, of the shank, longitudinally and it tests the weld, or in the case of big commercial anchors - the articulated joint. Its all well and good, we do need to know the welds are strong enough and we do need to know, in the case of a Fortress, that the articulated joint is strong enough. However the test takes no account of lateral loads, which are quite common for yachts, but not for commercial vessels. 'Proof Testers' say that the test actually also tests for lateral loads, which might be true for big commercial anchors whose cross sectional area is roughly square, or at most 2:1, but our cross sectional areas, of the shank, are commonly 10:1 - and that is not tested.

The reality is that welds and joints do not fail, or so seldom not to merit comment, but shanks do bend. They do not generally bend at the junction of shank and fluke but at the end of the horizontal lever arm - and a lever arm built from thin mild steel will bend earlier than one made from ASTM 514 and Proof Testing does not measure for a 90 degree load factor.

Proof Testing is important - but there is something missing and that is some form of 90 degree stress test - especially when anchor makers do not define from what their anchors are made (and do not conduct proof tests either)

Why would anyone buy a proof tested shackle, a tested chain but an anchor without any mention of proof testing nor quality of steel - beggars belief.

[JonJo]

Originally Posted by DumnMad

Read the Bisalloy link JonJo. Note they take care to compare strength with Gr250 and not Gr500. Note also its welding in general that affects the parent metal.

I'm picking the anchor manufacturers have designed around this susceptibility making the failure point away from the weld but they are wrong to make big claims about steel superiority.

http://www.bisalloy.com.au/applicati...20bisplate.pdf

Looking at 'failed' anchors - failure does not occur at the weld, or shank/fluke interface it occurs, as above (previous post), at the end of the lever arm. In fact the 'vertical' section of failed flukes is usually 'sound' or straight. The strength is needed at the end of the long 'horizontal' section of a typical 'L' or Delta shaped shank (rather than the short vertical section). If you have high tensile strength you can resist bending, if its thin mild steel it will bend like wet MDF.

ASTM 514 is worth shouting about because its almost indestructible - which is why its used in boilers, nuclear submarines and Manson and Anchor Right anchors.

I visited Bisalloy last week, their steels are used in the fins of keels for performance yachts. They suggest that if the engineering is sound and the weld is completed correctly then the weld should be as strong as the strongest of the 2 pieces of steel being joined.

[noelex 77]

Originally Posted by congo

This vertical test gives you max leverage the big destroyer, more importantly it gives you shank strength seperation of weld strength and just as important the fluke plate.

That suggests to me that if the fluke was jammed especially if caught near the tip you believe the force on the fluke/shank weld would be much higher on the Super Sarca than on the Rocna by virtue of the leverage imposed by the design.

I am sure the Super Sarca is strong enough, but I don't see how that is a positive attribute.

As I indicated I really don't place much faith in Rocnas video, but both the Rocna video and your photos of proof load testing show the force in a very similar and logical point.
To advocate moving the attachment point when testing your anchor to even out the distance from the shank because the design of the Super Sarca imposes more load on the joint does not make sense to me.

Reading between the lines, if I understand correctly, you believe if the attachment point is left in the same place the permanent deformation point for the 185kg Super Sarca to be a bit over 20T. If I misinterpreted my apologies, what is the correct figure?

If we believe Rocnas video the 17T withstood by the smaller 55Kg Rocna looks impressive if that is the case (and we believe them).

[Snowpetrel]

Originally Posted by Andrew Troup

I was going to gloat about the guy lying to two anchors without a tangle, but when I read more carefully, he did have to untangle the kedge on two occasions when the winds had fallen light.

When the winds were strong, he was sheering a lot less through lying to two anchors...

Good job he was using rope rode for the second anchor, It's almost impossible to untangle two chain rodes if it's blowing... I would never use two chain rodes unless I had a stern anchor or shoreline out, or a continuous anchor watch like we always had on the ships.

Being paranoid in nature (and not owning a New Gen anchor) I often use second (and occasionally third) anchors if it's blowing and find them very useful to reduce sheering at anchor, but I always use rope (except for the first few meters or so). Also my rodes are all cut to about 50 meters which makes it very easy to untangle or ditch in a hurry, and easier to manage in general.

[congo]

Noelex, I think there is somthing else thst stands out like dogs b----Iam sure you can understand this, have a look at the substancial lugs welded to the fluke, this is a reinforcement on the very pulling area, simply cannot, not possible , not allowed any welding to any part of the anchor in question when performing a proof test, this all has a ring to it.
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I can remember someone saying their shanks were made out of this and then we found out they were made out of that, what is the message hear, don't some people learn.

Regards Rex.

[Snowpetrel]

Originally Posted by Shanaly

Some here anchoring in coral weld a rounded shoe to the bottom of the pointy end of a plough. Also they add lead. Holding is great anywhere, and it doesn't cut and 'plough through' coral.

Very interesting! got any photo's or diagrams?