Anchor snubber design.

[BelleSerene]

All that yanking before fitting the snubber may feel satisfactory, but as has been pointed out all it's doing is smoothing the force applied to the anchor while you're applying the force with engine and waves. So the peak force you apply is lower than it is if, unsnubbed, wave motion varies it every couple of seconds. So long as you bother to apply a reasonable setting force with engine or wind in the first place, the anchor will set fully so it makes no difference whether you've fitted the snubber first. But there's a force at which any anchor will break out - and by not smoothing the force it's more likely that a peak yank will loosen the anchor's hold and you'll never know it. So snubbing the anchor without snubber fitted really achieves very little to nothing, and runs a small risk of defeating its purpose.

Anyway, isn't the bigger picture this? Feels to me that the focus on digging the anchor in with such hard, unsnubbed tugs really deeply provides more peace of mind than real security. It distracts from the fact that once the tide changes, which will be within six hours of you anchoring, the pick is going to have to dig in the other way around (unless there's such little tidal force that it stays put, operating backwards, in which case giving it such an extreme yank was unnecessary anyway) - and this time it's going to have to do all the setting by itself, unaided by all that un-snubbed tugging with an engine. (I believe, BTW, this is the best reason for using a NG - and I do mean concave - anchor. You are going to check your anchor's initial set anyway, so what most defines your safety at anchor is the thing's oft-ignored ability to re-set on change of tide, without first dragging.)

 

[Polly's Kettle]

Anyway, isn't the bigger picture this? Feels to me that the focus on digging the anchor in with such hard, unsnubbed tugs really deeply provides more peace of mind than real security. It distracts from the fact that once the tide changes, which will be within six hours of you anchoring, the pick is going to have to dig in the other way around (unless there's such little tidal force that it stays put, operating backwards, in which case giving it such an extreme yank was unnecessary anyway) - and this time it's going to have to do all the setting by itself, unaided by all that un-snubbed tugging with an engine. (I believe, BTW, this is the best reason for using a NG - and I do mean concave - anchor. You are going to check your anchor's initial set anyway, so what most defines your safety at anchor is the thing's oft-ignored ability to re-set on change of tide, without first dragging.)

How very simple and well put. It's changed my view on anchoring. I've always been aware of this of course, but not in quite such clear terms. I have a Delta, with no plans to change it as I don't anchor that often, but the re-setting issue will make me think about it a bit more for sure.

 

[Neeves]

How very simple and well put. It's changed my view on anchoring. I've always been aware of this of course, but not in quite such clear terms. I have a Delta, with no plans to change it as I don't anchor that often, but the re-setting issue will make me think about it a bit more for sure.

This is the problem with an anchor that has a clogged fluke - it will not re-set until the fluke is sufficiently clear to allow it to re-set unaided. It is for this reason Morgan's Cloud removed their recommendation for a roll barred anchor they had initially praised.

Jonathan

 

[GHA]

Feels to me that the focus on digging the anchor in with such hard, unsnubbed tugs really deeply provides more peace of mind than real security. It distracts from the fact that once the tide changes, which will be within six hours of you anchoring, the pick is going to have to dig in the other way around (unless there's such little tidal force that it stays put, operating backwards, in which case giving it such an extreme yank was unnecessary anyway) - and this time it's going to have to do all the setting by itself, unaided by all that un-snubbed tugging with an engine.

Couple points, tide change the better anchors don't tend to reset, they "walk" round still set. Check out the huge amount of work noelex has uploaded for our perusal. http://www.cruisersforum.com/forums/f118/photos-of-anchors-setting-126073.html


Also, as per post 76 I prefer to not be too precise - drop the hook, doesn't matter what orientation it is just don't pile chain on it. Then when it takes the load it could be pointing any direction. Then when it bites with a load of momentum from heavy steel boat that I think a bit of confidence is allowed

Tide isn't likely to cause many problems anyway, it's the 3am squall as the boat shoots off in a different direction that will give you grief.

 

[Neeves]

Couple points, tide change the better anchors don't tend to reset, they "walk" round still set. Check out the huge amount of work noelex has uploaded for our perusal. http://www.cruisersforum.com/forums/f118/photos-of-anchors-setting-126073.html


Also, as per post 76 I prefer to not be too precise - drop the hook, doesn't matter what orientation it is just don't pile chain on it. Then when it takes the load it could be pointing any direction. Then when it bites with a load of momentum from heavy steel boat that I think a bit of confidence is allowed

Tide isn't likely to cause many problems anyway, it's the 3am squall as the boat shoots off in a different direction that will give you grief.

I would agree with most of this.

I have found that if the change of tension angle is greater than 150 degrees, which is what you might have in a tidal river, then the anchor will somersault if the tidal flow is sufficient. If the tension slowly moves through 180 degrees the anchor will turn - but this is not the effect in a tidal river where you will slowly drift and then the tension slowly increase possibly beyond the ability of the anchor to hold it. If the anchor is clogged with river mud - hope that it self washes quickly!

You will get that same 180 degree shift if a thunderstorm passes right over you or if you are in an anchorage subject to bullets at 180 degrees - the anchor will somersault.

So do not rely on that slow swivelling round - been there, done that (and tested it)

Jonathan

 

[GHA]

So do not rely on that slow swivelling round - been there, done that (and tested it)

Not had a problem so far, even on worst night ever getting hurled around an anchorage with 60Kt gusts coming from all directions. Most tidal resets was something like 300 in one place. I find twisted chain is more likely to cause difficulties getting the chain back up when in a tidal anchorage for a while

Not had a problem,,,,, so far........

 

[Neeves]

Not once had a problem, even on worst night ever getting hurled around an anchorage with 60Kt gusts coming from all directions.

Not had a problem,,,,, so far........

And may you continue to be lucky.

When we were subject to what you describe (Storm off the Southern Ocean funnelling through Bass Strait) we chickened out, went right up to the beach (easier in a cat), cat stern to, deployed 2 anchors off the bow in a 'V' and tied to a tree. Stable as a rock for 3 days. The other yacht did similar, one anchor, 2 stern lines in a 'V' to trees (they had sailed from the UK across the Atlantic, Panama, Pacific and had reached southern Oz).

We quite often use trees (or rocks) and carry gear to complete.

Jonathan

 

[noelex]

You are correct that the ability to cope with a change in direction of pull is a very important property of an anchor.

An anchor that is good at responding to a change in direction of pull if it is well set in a reasonable substrate, will almost always "shuffle" or remain engaged with the seabed and pivot around.

This is just one example where the Mantus has responded to a change in direction of about 130°. You can see the scrape marks of the shank as is has pivoted just below the surface.

I have seen anchors do multiple 360° rotations on some occasions and otherwise not move. It needs to be set reasonably for the anchor to rotate in this way.

I think anchors can occasionally somersault, but in over 2000 nights at anchor I have never seen my Mantus or the previous Rocna do this. I usually dive on the anchor if there is any significant change in conditions. So I think somersaulting is very rare if you choose an anchor model that rotates well and it is set reasonably.

 

[BelleSerene]

This is the problem with an anchor that has a clogged fluke - it will not re-set until the fluke is sufficiently clear to allow it to re-set unaided. It is for this reason Morgan's Cloud removed their recommendation for a roll barred anchor they had initially praised.

Jonathan

Can I suggest that whilst that could occur if you're unfortunate enough to jam a rock of just the wrong size 'twixt fluke and roll bar, it won't if it's just mud. Mud pushed up the fluke from the tip end just displaces mud in the fluke.

 

[GHA]

Mud pushed up the fluke from the tip end just displaces mud in the fluke.

Is that from observation? I've often wondered, seems pretty solid some days. Not just with a rocna, happens with a spade as well.

 

[BelleSerene]

Is that from observation? I've often wondered, seems pretty solid some days. Not just with a rocna, happens with a spade as well.

Solid when it's sunbaked forward of the bow, isn't it?! Perhaps not the same substance, and in the same watery environment, as the bit of mud that follows it.

No, I haven't observed - and would condemn any such observation that I made to the same small-sample insignificance as many observations on anchoring! But it seems far more reasonable to believe than that once there's mud in your concave fluke, other mud on the sea bed (a) circumvents it and (b) doesn't exert just the same force on it as the column of mud ahead of an anchor that's been buried for the first time?!

 

[Fortress Anchors]

You are correct that the ability to cope with a change in direction of pull is a very important property of an anchor.

An anchor that is good at responding to a change in direction of pull if it is well set in a reasonable substrate, will almost always "shuffle" or remain engaged with the seabed and pivot around.

This is just one example where the Mantus has responded to a change in direction of about 130°. You can see the scrape marks of the shank as is has pivoted just below the surface.

I have seen anchors do multiple 360° rotations on some occasions and otherwise not move. It needs to be set reasonably for the anchor to rotate in this way.

I think anchors can occasionally somersault, but in over 2000 nights at anchor I have never seen my Mantus or the previous Rocna do this. I usually dive on the anchor if there is any significant change in conditions. So I think somersaulting is very rare if you choose an anchor model that rotates well and it is set reasonably.

Of course, a massively oversized anchor (in this case 125 lbs / 57 kg) with minimal deep-burying capability (as previously noted with the shallow fluke angle) will be able to shuffle around, so to speak, on a pristine sand bottom with directional pull changes.

Additionally, an anchor which is this massively oversized for the boat might also insure a greater factor of safety during common straighter pull loads, and compensate for the design deficiency of a shallow fluke angle and the possibility of cracking the weld in the fluke.

In 20 years with Fortress, I have rarely, if ever, heard of anyone using an anchor of that size and weight aboard a boat that is less than 50 ft, so this example, along with the clear water & pristine sand, is unusual as well.

Concerning the soft or thin mud Chesapeake Bay tests, we certainly expected and even welcomed the scrutiny from a doubting boating public, which is exactly why the boating media (representing magazines with over 1 million readers) were invited aboard with complete transparency to witness these tests.

Over the course of 4 days / 60 pull tests, every anchor was pulled using the exact same starting scope and for the exact same distance, speed and time. Without exception, there was not a single follow up story that was written which hinted at any favoritism shown to the Fortress anchor.

In fact, with the test protocol we put our product at a distinct disadvantage by using an initial long starting scope, which we advise against with our Safe Anchoring Guide instructions:



And yes, surprise surprise (as Noelex mentioned) the Fortress performed the best, which really wasn't a surprise to anyone with knowledge of anchor design and performance in soft or thin mud.

Large anchor manufacturers such as Bruce, Baldt, the US Navy, and Vryhoff all make anchors with a wider shank / fluke angle to improve holding capacity in this type of soil, so the Fortress' superb performance at the adjustable 45° angle during this testing was, once again, no surprise.

Further still, the poor performance of the new and old generation "fixed fluke" anchors was also no surprise. Our consultant on this project was Bob Taylor, who has close to 50 years of experience in anchor design and soil mechanics with the US Navy and the offshore industry, and he has worked directly with Bruce and Vryhoff as well.

Bob stated that "Anchors which are designed and optimized for a harder soil will typically only have a holding ratio (holding capacity divided by anchor weight) of only 10-15x when used in a softer soil," and that is what we found in the Chesapeake Bay.

The 44-46 lb (20-21 kg) anchors typically held between 450-700 lbs (200-315 kg) during these pull tests, with a few exceptions.

 

[GHA]

Solid when it's sunbaked forward of the bow, isn't it?! Perhaps not the same substance, and in the same watery environment, as the bit of mud that follows it.

No, I haven't observed - and would condemn any such observation that I made to the same small-sample insignificance as many observations on anchoring! But it seems far more reasonable to believe than that once there's mud in your concave fluke, other mud on the sea bed (a) circumvents it and (b) doesn't exert just the same force on it as the column of mud ahead of an anchor that's been buried for the first time?!

Not being big on soil dynamics I've no idea what seems more reasonable to be honest. I've a rocna and spade onboard, both can come up with some fairly solid stuff in the flukes but both have always stayed very close to the same place when the direction of pull changes. No idea what's going on though

 

[noelex]

Concerning the soft or thin mud Chesapeake Bay tests, we certainly expected and even welcomed the scrutiny from a doubting boating public

Brian, in my view I think any time an anchor manufacturer designs the test protocol, determines the test conditions such as the rate of pull, and importantly picks the exact spot where the test will take place, then the test cannot be seen as independent.

I think it would have helped to at least have someone independent examine the raw test data and produce the graphs. I have looked at the raw data as supplied, and on my analysis I cannot see how the Fortress set at 32° beat the Danforth set at the same angle, as presented in your summary graph. Perhaps you could explain how the raw data was converted to the graph for these two results you have posted?

I have also been contacted by someone in the industry concerned that some results were discarded and not included in any of the the raw data. I have no idea if this true, but I have been puzzled about the widely reported (including by yourself) first pull of the Fortress that apparently developed almost no holding power. The description of this apparently very poor result by the Fortress does not seem to correspond to any published raw data. Is this pull included in the raw data and if so where?

Where any results simply excluded? If so, how was decided which results were excluded and who decided this?

This is off topic for this thread. Perhaps it would be better to start a new thread on these questions.

 

[Fortress Anchors]

Bob Taylor and Chuck Hawley, the former VP of Prroduct Testing for West Marine, reviewed the test by test individual performance graphs that were the result of measurements taken by a running line tensiometer and shown on computer monitors aboard the test vessel, and in full view of the boating media. Both gentlemen came up with similar results.

The 21 lb Fortress @ 32° and the 35 lb Danforth were very close, as indicated in the individual graphs and final performance chart.

While other anchor manufacturers might question all aspects of this soft / thin mud bottom testing, none have provided their own test data in this sea bottom condition to refute the findings. Maybe you should question them as well?

 

[noelex]

Brian, you have posted that you "welcomed the scrutiny from a doubting boating public" which is reassuring, but you have not answered any of my questions or concerns.

As an anchor manufacturer, if you post on this forum graphs of tests that Fortress have arranged and analysed, I think you should be willing to answer questions about this data.

 

[Fortress Anchors]

The testing was three years ago in August 2014 and I do not recall any pull test being discounted or excluded.

Meanwhile, you continuously promote the Mantus anchor while never mentioning that it was massively oversized for your former boat, nor have you ever addressed the images of the weld crack in the Mantus fluke. May I humbly ask why?

 

[noelex]

The testing was three years ago in August 2014 and I do not recall any pull test being discounted or excluded.

Brian, journalists on board during the tests Fortress conducted have reported that there were discounted or excluded results.

This was just one of the public comments:
"The test protocol called for discarding fouled anchors in making the final judgment."

If some results were excluded, it should be made clear specifically which results from which anchors were discarded. This is especially important when an anchor manufacturer is conducting the test and the analysis.

I am still puzzled why your graph shows that the Fortress at 32° beat the Danforth. Even ignoring the possibility that some results were excluded, and simply examining the raw data you present, I cannot see how this conclusion was drawn. Could you please clarify?

 

[Neeves]

Brian, you have posted that you "welcomed the scrutiny from a doubting boating public" which is reassuring, but you have not answered any of my questions or concerns.

As someone who has hundred if images of one specific oversized anchor which has no admitted faults maybe you can answer the questions previously raised.

The cracked fluke on the Mantus toe

The assertion that a well set anchor, I assume to be a Mantus, can be used at short scope

The contradiction that you say a modern anchor sets with the toe and shackle simultaneously but this is never, ever, shown with the Mantus

and an additional question

You claim the Mantus is as good as a Rocna - evidence?

Though I do admit you do not really welcome the scrutiny of the boating public - and any dissent is ignored or a mechanism devised to remove it.

Jonathan

 

[Neeves]

I'm not sure why, Noelex, the Fortress should not beat the Danforth. The danforth has thicker fluke plates that are not bevelled for entry. The Fortress has bevelled and streamlined shank. Why is the Vulcan shank, original Bruce, Spade shank chamfered if it does not improve performance. Why does the Mantus have a very sharp toe if it does not improve performance.

Just look at the 2 anchors side by side and examine the small differences - its not rocket science. Just powers of observation - which I think you demonstrated with your condemnation of the Kobra.

Jonathan