Photos of Anchors Setting

[noelex 77]

I spent a pleasant few hours in the shallows of the bay with a Guardian G5, my tender anchor. This is the smallest of the Fortress/Guardian range. It is only suitable for boats 4-5m (12-16 feet) and is only 1.1 kg (2.5lb) so it is a much smaller anchor than we would use on our cruising boats, but this makes it very easy and quick to test. There are some scale effects with anchors and this anchor is small so the results should not be directly compared, but these results are interesting on there own.

The anchor had 4m of chain, the rest was rope. All the photos were in about 1m of water. The scope was well above 10:1

The aim was to show the rotation of the anchor to a change in direction of pull. Unfortunately, the Danforth/Fortress/Guardian anchors do have a weakness in this area. The anchor can sometimes develop a very high list. The stock digs in and the anchor corkscrews out. In most cases it will reset to the new direction and the owner is unaware, but the behaviour is easy to observe underwater.

I wanted to start with good bury before getting photos of the rotation.
Unfortunately, I could not get the Guardian to set really well. This was disappointing and puzzling. It has previously set well. I tried several locations with multiple tries around the bay in what appeared to be good sand, but I think it was just too hard for the anchor.

So the rotation photos will have to wait for another day.

Here are the photos of the anchor setting and breaking out. These are interesting in themselves. This is the first location. I will process the other photos and post them when I can.

The Anchor:




Starting to set:




The best set achieved with this pull:




Breakout:

[noelex 77]

This was the best set of the day. It was good enough for a rotation test, but I went for a bit better hoping the anchor would level out. Unfortunately, it broke out.

Start:




Best set achieved for the day:




Breakout:

[goat]

Noelex,
I think Mantus owes you a dinghy anchor, or if they don't, we do.


goat

[noelex 77]

In this location the anchor dragged for a long way with a high list. It eventual broke out:









Breakout:

[JPA Cate]

noeles and Seaworthy Lass aka mermaid,

Thanks for the wonderful Christmas "card". It brought a great smile to both our faces.

Interesting about the dinghy anchor. How much force did it take to break it out?

As Happy Md Sailor said, a wonderfully effortful and informative thread...thank you both very much.

Best wishes for the New Year!

Ann & Jim

[Seaworthy Lass]

Originally Posted by HappyMdRSailor

LOVE IT!!!

Thanks for "definitely" the most labor intensive and informative ongoing post on CF....

Merry Christmas to ya both!

Originally Posted by Ann T. Cate

noeles and Seaworthy Lass aka mermaid,

Thanks for the wonderful Christmas "card". It brought a great smile to both our faces.

As Happy Md Sailor said, a wonderfully effortful and informative thread...thank you both very much.

Best wishes for the New Year!

Ann & Jim

Thank you for the lovely comments

I have really enjoyed the diving challenges, but like all mermaids I prefer to stay out of the limelight .

Best wishes to everyone for a joy filled 2015.

SWL x

[noelex 77]

Originally Posted by Ann T. Cate

noeles and Seaworthy Lass aka mermaid,

Thanks for the wonderful Christmas "card". It brought a great smile to both our faces.

Interesting about the dinghy anchor. How much force did it take to break it out?

Thanks Ann.

I don't have a strain gauge, so I can only make a guesstimate. I started out using the dinghy motor (which is 4hp) and I could not get the anchor to hold more than about 2/3 throttle in reverse. I changed to a shoreside pull because it was easier. The maximum holding force was well below what could be pulled by hand. Maybe 30-40 kg?

Remember this is a small anchor almost 8 times lighter than say an FX-37 (the FX-37 also has a slightly more machined shank and fluke).

I think we can broadly consider that the results in traditional anchor tests using say 10-15 kg steel anchors also applies to the anchors that we use on our yachts which are usually a couple of sizes larger, but scaling up the results from a very small anchor like this not really valid.

Nevertheless, the small size made it easy to do multiple trials directly observing the anchor, which I found interesting. I still hope to find a location where the anchor will set well so I can do some rotation tests. Some quick beach trials last year suggest it is going to behave in exactly the same way to a change in direction of pull as its bigger brothers.

[noelex 77]

The final photos. There were quite a few other trials where the anchor just refused to engage at all.

[lancelot9898]

Appreciate all your efforts norlex in posting the pictures. I think the photos themselves are more instructive than many of the anchor tests done by the manufacturers. I have a friend who claims that he used a Danforth anchor during a hurricane and it dug in through the mud several feet such that it could not be retrieved. Instead of attaching the chain or rope directly to the Danforth , he used a 5 or 6 foot cable. He called it a cheese slicer which allowed the anchor to penetrate deeply into the mud. Such an anchor would be very dependent on the bottom composition and I don't think it would be very suitable for most anchorages, but thought it might be a good ideal for specific locations and conditions. My 2 cents.

[Kenomac]

We use a simple folding grapple anchor for the dinghy. I'm always impressed with how well the little bugger holds.

[noelex 77]

Thanks for your kind words.

The thin cable idea is one that is a worthy one. It is used on some of the oil rig anchors and XYZ supplied a SS cable for their anchor for this purpose.

Normal chain develops a reverse catenary as it pulled under which reduces the anchors diving ability. There are a few practical problems.

• SS cable with swages for this application makes people nervous.
• A long distance between the anchor winch and end of the shank is needed. Few boats have this.
• The catenary close to the anchor is less (because the wire is lighter)
• Most modern anchors set by falling on their side. If they land upright the weight of the chain helps pull them into the correct setting position (this does not apply to Danforth anchors)

The last point in particular does not seem to have received any attention.

I think we need some experimentation.

[noelex 77]

We are still at the same anchorage. The forecast has included predictions of at times over 40 knots rapidly shifting back and forth from north to south. In reality the winds have been lighter but it has reached 30 knots every couple days switching 180 degrees. With these rapid changes in direction the more exposed anchorages simply cannot be used.

Frustratingly, the wind has stirred up the bottom mud so that it has been impossible to find the anchor. There would have been some great examples of the anchor rotating around to a new wind direction. Unlike sand, the mud covers up the marks very rapidly so there is no trace of any rotation, or movement.

Today it cleared up enough to get a glimpse at the Mantus. It has buried further. Generally it takes about 30 knots to exceed the setting force and cause the anchor to dive deeper.

The Chrismas decorations are hanging in there .

[monte]

On the dinghy anchor subject, we have been using a folding grapnel which works ok in rocks but not in sand. Yesterday we used it as a stern anchor to hold us off the jetty at Roseau and unfortunately it held too well and removing it required a bit of effort. Too much effort and it finally came up sans grapnels. Time to look for a new dink anchor.

[noelex 77]

This is the appearance of the Mantus after setting to act as reference:

[noelex 77]

The can in the top of the picture acts as reference mark, although it is difficult to be positive that it has not shifted. It shows the Mantus has not moved back. It has rotated about 20 degrees. I am sure that in the interim it has spent many days 180 degrees from this direction. My guess is that it has several rotations. The lack of other movement shows, as you would expect, that there has not been any breakout and reset. Besides I think the Christmas decoration probably would not have survived. I am surprised it still on.

The Mantus now: (edit this was a few days ago I thought I had posted these pictures)




12 days ago: