Photos of Anchors Setting

[kas_1611]

Thing is on a large ship there will always be someone on the bridge and at least 1 engine will be running to provide electrical power so if there are any signs of movement whilst "anchored" action can be taken quickly.

Well that's the theory at least and in my experience on deepwater drill ships anchored in harbour it is exactly what happens. Not that we dragged whilst on the hook in Singapore Bay.

Keiron

[noelex 77]

Here the throttle was shut off. The anchor was never stationary, but may have managed that given a longer distance:

Unfortunately, in weed like this it is very hard to tell from a photograph how well the anchor is set. I rely mostly on feeling with my fingertips, but by parting the weed with my hands it is usually also possible to see parts of the fluke indicating they are not buried into the substrate under the weed.

In this case the tip has penetrated reasonably into the underlying substrate which is very promising. The weed roots are tough and the anchor will not penetrate as deeply as it will in sand, but once the tip has found its way below the roots the rest of the fluke usually follows if more force is applied. So a good result. This is one of the best results for a convex plow anchor in weed that I have seen for a long time.




Here is the final result after the "dust" has cleared:

[Muckle Flugga]

Originally Posted by Ann T. Cate

"They are not particularly useful as a small boat anchor." Muckle Flugga

Do they work for ships, then?

Any pics?

Ann

Hi Ann,

Stockless or Patent style anchors are nearly ubiquitous on medium to large ships. I don't have any pics of them setting, per se, but if you google images of, for example, US naval vessels or commercial ships and look carefully at their anchors you will see what I mean.

Aye,

S

[noelex 77]

Big ships don't anchor like we do. They rely much more on the weight of the chain.

Here is a photo of an admiralty stockless anchor from last year. At the other end was a 119 foot superyacht. The anchor was not doing well. It had a list of almost 90° and was slowly dragging. It is difficult to get an idea of scale in the photo, but the anchor was huge compared to the anchors on our sized vessels. The big flat plate sat flush with the side of the ship when the anchor was raised.

Of course this is only a small anchor compared to models the really big ships use, but these vessels are typically anchoring in 30m so free diving photos are not possible.

[noelex 77]

This was an articulated plow anchor (CQR copy).

As you can see, it has just been dropped with no force applied. An anchor will just sit on the bottom with this treatment.

Despite the hinge, the anchor is happy sitting bolt upright.

Many are convinced it is worth pausing for minutes, or hours, before applying any setting force on an anchor. They believe this results in a better set. I think this idea has some merit in conditions where the anchor is given some force due to the wind pressure, but I have my doubts if the pause does anything in light wind like this.

This anchor had been sitting like this for a couple of hours when the photo was taken. Would it have looked any different just after it was dropped? Are there changes to the substrate that we cannot see?

Anyway, something to contemplate if you always use the "drop the anchor, pause, and have a cup of coffee before setting it" technique.

[Hydra]

Originally Posted by Muckle Flugga

Hi Ann,

Stockless or Patent style anchors are nearly ubiquitous on medium to large ships. I don't have any pics of them setting, per se, but if you google images of, for example, US naval vessels or commercial ships and look carefully at their anchors you will see what I mean.

Aye,

S

Stockless or Patent anchors aren't nearly as effective as yacht anchors are. Ships drag very often in gales.

Alain

[kas_1611]

Originally Posted by noelex 77

This was an articulated plow anchor (CQR copy).

As you can see, it has just been dropped with no force applied. An anchor will just sit on the bottom with this treatment.

Despite the hinge, the anchor is happy sitting bolt upright.

Have to admit it took a lot of skill to get it to land like that and even more to keep it bolt upright. A little like the yacht that ran aground in the Solent a little while back and stood up on its keel until the tide came back in to refloat it. You couldn't do it again if you tried!!

[jongleur]

[/QUOTE]

I bet the hinge is rusted solid and cannot
move.

[noelex 77]

This is a Delta. A local octopus decided it made a nice holiday home. Like the anchor's human owner, the squatter might have hoped for a bit more bury. I think both of them would would have been a bit safer.

[noelex 77]

This is another convex plow anchor.

I think this is a model made by Anchorlift called the "Shark". They seem to have changed the name lately to "Pro Plow". I'm not sure if they have altered the design slightly or if it is just the name.

There are a lot of companies producing these fixed convex plow designs and it is difficult to identify all the models, so I may be wrong.

This was not doing well in my opinion. You can see it has been dragged several metres and to me it just does not look like it wants to set. Note the tip is an inch or so above the substrate still.

Anchors have little hope of digging in until the tip of the fluke penetrates the substrate. Ideally the anchor design should ensure a a lot of downwards pressure on the tip to force it under the substrate. It is not good when the anchor can sit with the tip not touching the substrate .

This is a failure mode I sometimes see with the convex plow anchors. They can in some circumstances appear to drag large distances with the tip above the substrate for much of the time. Look also at the Delta in post #1764 or post #1746 for some other recent examples.

My theory is that this occurs most often when there is a reasonably soft substrate with a very thin harder layer on top. The back of the fluke sinks down in the softer sand reducing the angle of attack of the tip, but the whole fluke does not sink, as it is supported by the thin harder layer.

A major part of the problem is that some of these anchors have very little force on the tip in the normal setting position, which is why they struggle in harder substrates and take a long distance to set.

Anyway, this is only my interpretation. As always, you should look at the photos and make up your own mind:

[Muckle Flugga]

Originally Posted by noelex 77

This is another convex plow anchor.

I think this is a model made by Anchorlift called the "Shark". They seem to have changed the name lately to "Pro Plow". I'm not sure if they have altered the design slightly or if it is just the name.

There are a lot of companies producing these fixed convex plow designs and it is difficult to identify all the models, so I may be wrong.

This was not doing well in my opinion. You can see it has been dragged several metres and to me it just does not look like it wants to set. Note the tip is an inch or so above the substrate still.

Anchors have little hope of digging in until the tip of the fluke penetrates the substrate. Ideally the anchor design should ensure a a lot of downwards pressure on the tip to force it under the substrate. It is not good when the anchor can sit with the tip not touching the substrate .

This is a failure mode I sometimes see with the convex plow anchors. They can in some circumstances appear to drag large distances with the tip above the substrate for much of the time. Look also at the Delta in post #1764 or post #1746 for some other recent examples.

My theory is that this occurs most often when there is a reasonably soft substrate with a very thin harder layer on top. The back of the fluke sinks down in the softer sand reducing the angle of attack of the tip, but the whole fluke does not sink, as it is supported by the thin harder layer.

A major part of the problem is that some of these anchors have very little force on the tip in the normal setting position, which is why they struggle in harder substrates and take a long distance to set.

Anyway, this is only my interpretation. As always, you should look at the photos and make up your own mind:

Ok this one is truly awful.

[Muckle Flugga]

Originally Posted by Hydra

Stockless or Patent anchors aren't nearly as effective as yacht anchors are. Ships drag very often in gales.

Alain

This may very well be the case… but they stow well at ships bows in an automatic sense, and given their ubiquity, and the number of yachts I have seen wrecked over the years (scores and scores and far more proportionately than heavy ships) by crap anchoring, I wonder where you get your data/assertion?

[DefinitelyMe]

Hey guys. I've been following this thread for several months now but haven't contributed because i don't have a camera :-(. Really fantastic stuff; you have created what is probably the most comprehensive collection of real-world anchoring data in existence.

2 musings for the experts (Noelex, That's you!):

1) Why do you think ships haven't come up with anything better than what is essentially just a lump of metal on the seabed? I spent about a year on a tallship. Steel, 180-feet sparred, some 550 tons displacement. We had two anchors. The primary was a 2.5-ton navy anchor. The secondary (on account of it being more awkward) was a 3.5-ton fisherman. Both dragged on several occasions and often in what should be good substrates (sand and/or mud mainly). I realise the navy anchors stow nicely, but surely that can't be the whole story? Do you have any thoughts on the matter?

2) I have always subscribed to the 'bigger is better' philosophy but having spent many hours looking through your pictures i'm reconsidering that. I have a rocna 25 on my 36-foot boat and it is probably a size too big i'd say. I've never managed a complete bury from the force of the engine alone - the engine simply isn't powerful enough. Normally only the tip is buried. Because of this, when the breeze shifts around and the anchor rotates it does so relatively easily and often breaks free before re-setting. Looking at your mantus pictures i'm thinking that it might not necessarily be a good thing to have an over-sized anchor because a smaller one is likely to bury more completely, probably set faster and more completely (on account of having a smaller amount of bulk that needs to penetrate the seabed) and be much more resistant to break-out once set. Many of your pictures show anchors that are only partially buried despite the owners having applied some setting force. Do you think they could have benefited from having smaller anchors in some cases?

Forgive me if i'm being inappropriate in posting here. I have no photos to offer, and i kind of feel like this thread is hallowed ground that should be revered but not tarnished by plebs such as me. I just couldn't resist :-)

[sanibel sailor]

I am not a big ship captain, but I understand that ship anchors are sometimes used as a "drogue" when maneuvering. Dragging it along the bottom can help bring the bow around when coming alongside. They may prefer not too good a "bite" at times.

[Hydra]

Originally Posted by Muckle Flugga

This may very well be the case… but they stow well at ships bows in an automatic sense, and given their ubiquity, and the number of yachts I have seen wrecked over the years (scores and scores and far more proportionately than heavy ships) by crap anchoring, I wonder where you get your data/assertion?

For example, DJ House writes, in "Seamanship Techniques, 2nd ed" (Butterworth Heinemann), p26:

The stockless anchor (...)
Holding power again varies depending on the nature of the bottom but, as a rule of thumb, it may be considered to be up to three times its own weight.

This is not an impressive performance: the holding power of yacht anchors often exceed 50 times their weight.

Ships drag anchor very often but, since they often anchor in open roadsteads, they generally have ample time to get underway and head to sea. The picture I posted is one of a coaster that couldn't make steerageway in a storm because it was light, so the propeller wasn't fully covered and the wind on the bow was pushing it sideways.

Alain