Photos of Anchors Setting

[noelex 77]

This was a Delta. 5m @ 4:1.

The anchor was dropped in patch of thick weed. It had dragged a long way in the weed through a small sandy clearing and had come to rest when it hit a large rock.

As it was jammed against a rock this anchor would have given the skipper the impression that the anchor was holding well and was nicely set. The danger is if the direction of pull changes the anchor will have very poor grip. The Delta did not manage the weed very well (it was thick weed so a tough test) and I would not give it much hope of grabbing if the anchor's grip on the rock failed.

When anchoring overnight always set an anchor alarm as an extra layer of protection. Even if you have tested the anchor with say full reverse it is no guarantee.

With rocks like this there is always the risk that the fluke can become jammed under the rock. This happens very rarely, but if want to minimise the risk of losing the anchor to rocks, debris, old moorings or power cables, an anchor that sets reliably and rapidly is by far the best defence. In my opinion, forget the rock slots and fancy gadgets and get a good anchor. If it sets very quickly and doesn't drag the chance of getting the anchor caught is minimised.

[noelex 77]

This was a CQR copy, sometimes called a plow anchor or an articulated (because of the hinge) plow.

This one had been dropped in soft sand, but at this stage had not had any force applied. This tells is nothing about the anchor performance. Pity, as the CQR or copy can usually bury quite well in this sort of soft substrate.

[noelex 77]

Oh, and when taking photos of anchors be mindful of where your shadow is falling. This looks painful :

[Jim Cate]

Oohhhh, OW!

Jim

[noelex 77]

When diving at this anchorage, the transition between the "normal" sand for this area (a hard layer underneath a thin soft covering) and the unusually soft sand was very noticeable.

It did not photograph well, but this gives you some idea. Keep an eye out for these sort of changes when snorkelling. The transition between different substrates can offen be seen if you look:

[noelex 77]

In the photo this looks like a massive ship's anchor. In fact, it was only about 30lb. 5m @ 4:1 with a mixed (chain and rope) rode.

It belonged to 30 foot yacht that was obviously designed and set up for racing with no anchor winch, minimal accommodation and lots of bits of string . Anyway, you can have great fun cruising on a boat like this, but sadly few owners seem to take advantage.

They had a weird sort of mini Stockless anchor. Interestingly, the Stockless anchor is often designed with a wide fluke angle of around 40-45° (versus the conventional 32° used on most anchors). Presumably this wider fluke angle is optimim for these anchors but they are typically massive, not 30lb anchors. This smaller Stockless seems to have copied that with a fluke angle of close to 40°. I am not sure that is such a good idea in anything other than a very soft substrate. It looks like the fluke angle may have been adjustable, but if so the alternative was possibly even wider.

Very little force had been placed on the anchor at this stage so this photo is of little help predicting the anchor performance. To my eyes the anchor design looks a poor choice. The very heavy crown will limit the penetration, although at at this stage with very little force the anchor is doing as well as could be expected.

[noelex 77]

The racing boat with the small stockless anchor was on a mixed rope/chain rode.

Unfortunately, yachts like this will swing quite differently to yachts on all chain rode. The biggest problem is in light and variable wind.

If we use a 10 knot wind that changes direction 180° as an example. The yacht on an all chain rode will rotate about the bow, but the light wind may not move the chain. So the yacht will face into the new wind, but the anchor will be behind the boat. In the same circumstances a yacht with minimum or no chain will find the rope will have little grip and the boat will not only rotate to face into wind it will move rapidly to the opposite side of the swing circle.

This creates the problem of conflict, and a possible collision.

A good solution is for the boat on the rope rode to use a kellet, or even better a small anchor as this boat has. In light wind the boat will not move as much. As the wind strengthens the kellet or a small anchor will lose grip (it will generally lift off the seabed) and the boat will move to the other side of the swing circle. However, so will the boat on an all chain rode, as the wind force overcomes the grip of the chain on the bottom. So the boats with a different rode swing in a similar way avoiding conflict.

If is of course tough to arrange things so that the boat with all chain and the boat with rope + a kellet or small anchor move the same but it is not difficult to at least improve upon the normally large difference. The kellet/small anchor does little or nothing to improve the holding in strong wind, but is helpful in its role to make the boat swing more like a boat on all chain (which is the default for cruising boats in many locations).

Here you can see the skipper has attached a small folding grapnel. This anchor will only have very low levels of grip, but makes the rope/chain rode swing in a more similar way to an all chain rode.

You can see the Grapnel anchor kicking up sand as it is dragged along the seabed:




This was the grapnel anchor:

[noelex 77]

This is a Delta.

It had only been dragged a few feet, which is not enough for the Delta to set even in soft sand so we cannot deduce much about how well it would ultimately perform.

[noelex 77]

This was at the same anchorage, but it was an area of horrible loose rock and gravel. The Delta was not doing well. You can see the long drag mark and the anchor was slowly inching back in the gusts, as we watched. This movement kicked up a fair amount of sediment. This made photography difficult. 6m @ 4:1.

In this sort of substrate it is very hard to predict how any other anchor design would have managed. The boat was close to ours and our anchor was in perfect sand. Even in clear water, the difference between the sand and this sandy coloured rock would be very difficult to pick when dropping the anchor.

The best defence is to both set and test the anchor with a reasonable amount of reverse, but even then the anchor may be hanging on to a slightly larger rock. A large anchor helps in these sort of terrible substrates, but nothing is likely to be truly reliable.

[noelex 77]

This was a disappointing, genuine CQR. 10m @ 4:1.. It was dropped in the softer sand using good technique, but the anchor was obviously not holding. This was their second drop, the first did not hold either. The drag mark was difficult to photograph, but extended for many boat lengths.

At the end of this the anchor was still on its side with not much more than just the toe digging in. Unlike some other anchors that have just been dropped, this anchor had been given some reasonable force and every chance to bury:

[noelex 77]

The was another fixed convex plow anchor, probably a Shark. It was the same anchor and boat (but a different anchorage) that I showed in post #1999.

Given the nice substrate, it too was doing rather poorly. You can see the setting mark. It was about 5m long. The fixed convex plow anchors normally need to be dragged 5-7m to set properly in the typical substrates usually seen in this area. This always looks an inordinately long distance when viewed underwater. So perhaps the anchor would have done much better given more setting distance, but in this lovely soft sand even the convex plow anchors can usually manage a short reasonable setting distance. It is harder substrates when they struggle more.

[noelex 77]

The Mantus remained unchanged.

I managed to capture this photo with a rainbow pattern on the bottom caused by a wave acting as a prism and dispersing the sunlight.

The digital red filter in the camera applies some compensation, but I was surprised that all the colours of the rainbow are present. I would have thought the red would have disappeared.

[artic warrior]

Hi Noelex,

Ive looked at all your pics and fab to view thank you.

Im making a mantus/rocna style concave part with the shank from a 25kg delta,,,and welding all parts

I believe a MASSIVE part in why the mantus works well is because of its wide rear where the roll bar attaches, that manipulates the tip to dig in earlyer and better. ?

Im 18ton 45ft.
You say your using a 58kg I think you said,
What size and weight is your boat.

Thank you

Colin

[noelex 77]

Originally Posted by artic warrior

What size and weight is your boat.

Our yacht is a custom designed aluminium vessel. It is 14.6m long (about 48 feet). It is stoutly built. The designed displacement is 14.5T, but we cruise full time and the boat is our home so we have a heap of junk useful gear on board, as well as large capacities such as 1000L diesel.

We started using a Rocna 55 kg 7 years ago and over the last 18 months have been using a 57 kg Mantus.

The concave roll bar anchors such as the Mantus, Rocna and Manson Supreme are all excellent performers and all are a great choice providing they fit. The concave roll bar anchors share a lot of similar characteristics, as you would expect, but overall in my opinion the Mantus is (slightly) the best of the designs. As you say, I think a large part of this is the wider base to the back of the fluke. This presents the tip at a very aggressive angle and helps with the initial penetration in tough substrates. I think the longer more tapered fluke Mantus has is also a help in weed. Finally the slightly less deep shank helps with the weight distribution. The drawback is the wider base of the Mantus and longer more tapered fluke make it a slightly bigger anchor overall.

Good luck with your home made project Colin. Post some pictures when it completed. There is a thread and whole user group devoted to homemade anchors here:

http://www.cruisersforum.com/forums/...ct-113732.html

[noelex 77]

This was a couple of Admiralty stockless anchors dropped by a small superyacht. 7m @ 3:1

Usually when deploying two they will drop one, motor back a bit and off to one side, then drop the other. For some reason this boat dropped them both together so they ended up quite close: