Photos of Anchors Setting

[noelex 77]

This Kobra was dropped a long way from our boat and much closer to the beach in 4m @ 6:1. Here the substrate looked better. There was no rock visible nearby and the sand looked almost powdery.

Anyway, not a great set with a long setting distance. Most of the modest amount of bury is just heaping up of the sand.

[noelex 77]

This was a Rocna dropped by a private catin 7m @ 5:1.
It was dropped in a sand patch surrounded by rock. Considering the difficult substrate, it is doing a great job. It has set very quickly, most of the fluke is buried with only a small amount of the underside showing due to a moderate list.

It is very difficult to evaluate the performance of different anchor models in a variable and difficult substrate, as this anchorage presents. However, performance in difficult substrates is in many ways more critical than the performance in an easy substrate. Reliability and versatility is a very important property of the ideal anchor. Unfortunately, anchorages like this are not included in traditional anchor tests.

Given the variables, it is important to look at a large number of examples, but I am struck once again by the pronounced difference between the excellent and lesser designs of anchor. There are several more examples coming up that I photographed today.

[noelex 77]

Unfortunately, old tyres are a common form of debris. I guess most of the problem is that they are so durable. Tyres are used as fenders by workboats and sometimes as moulds for concrete moorings, but it is still surprising how many litter the bottom. They do provide a hiding spot for fish and octopuses, but they also upset anchors trying to set. This was a big tyre.

It was about 6-7m from where the Rocna was dropped. You can just see the roll bar in the distance. The Rocna has set in only a little over metre so the tyre has not come into play, but I wonder if a convex plow anchor would have set before it hit the tyre in this situation?

[sneuman]

Just saw this video by Distant Shores. There's quite a bit of actual underwater footage here:

https://www.youtube.com/watch?v=w4qO_dIegaM

[Factor]

Originally Posted by noelex 77

I wonder if a convex plow anchor would have set before it hit the tyre in this situation?

Depends which type.

[noelex 77]

Thanks for the link.

It is a beautifully filmed video and well worth watching. I wish I could freedive that well.

[noelex 77]

This was a small Delta (35 lbs) attached to a reasonable sized private yacht (37' ?). They stayed overnight. 4m @ 7:1. The yacht was set up as a racing boat with triple spreaders, NKE instruments at the mast, and a retractable bow sprit. I suspect this is why they had chosen such a small anchor.

They did a very nice drop, but did not seem to notice that their anchor was not holding. Underwater you can see the long setting mark with a pretty terrible result at the end. The Delta has very little of its fluke engaged and has not even started to rotate upright, something the Delta normally does early in the setting process. As has been noted, the substrate in this anchorage is very variable, but this anchor was dropped closer to the beach in what looked like the best sand in the area. There was no rock near the anchor.

Anyway, I don't think this is as simple as the Delta just behaving poorly. Do any anchorholics have an alternative theory as to what is wrong?

[sanibel sailor]

What is the thing attached to chain? Soft cord? Metal bar? Might affect setting performance.

[evm1024]

Originally Posted by sanibel sailor

What is the thing attached to chain? Soft cord? Metal bar? Might affect setting performance.

Looks like a twist swivel Ocean Blue Twist Swivel Anchor Chain Connector Stainless Steel - Default

[Don C L]

Maybe it's just a thin layer of sand over a very hard substrate... Or maybe the Delta is just, well, less than perfect...

[malbert73]

There's something weird attaching chain to shank it seems? Keeping anchor twisted somehow? Or a bent shank?


Sent from my iPhone using Cruisers Sailing Forum

[noelex 77]

Thanks everyone for your participation.

This Delta has been attached to a self righting swivel (sometimes called a banana or a twist swivel). They have a swivelling end, but are much longer than a traditional swivel (typically 9 or even 12 inches) and they are banana shaped. The idea is that the swivel automatically turns the anchor the right side up as it comes over the bow roller. The main use is for power boats that want to retrieve the anchor without anyone on the foredeck.

I am not a great fan. They add extra complication and failure points.

It is very important even without a swivel that the chain/anchor connection cannot become jammed in an off centre position. The problem is more common than realised. It is worth testing the shackle or swivel used to make sure it has no tendency to jam in the wrong position. If the lead becomes unfair, the anchor can fail to set properly. If the anchor cannot get much grip, the force straightening out the connection will only be low and even a slightly jammed shackle can remain stuck. This is also a problem when using a rock slot.

A long self righting swivel compounds this problem considerably. If it becomes jammed the centre of pull will be displaced a long way from where it should be.

Of course it could be as Don suggests, but it is hard to image the anchor performing this poorly.

[noelex 77]

This was a small, near new Fortress. An FX-11. It was dropped by a small private yacht. They stayed overnight.

The anchor was dropped closer to the beach where the substrate was better, in 4m @ 6:1 (but half the rode was rope).

Unfortunately, they did not set the anchor directly down wind and so the anchor was forced to rotate about 40° to the prevailing wind direction shortly after it was set. You can see it has developed a high list, although it was not set with much force to begin with.
















Edit: Photos of what we awoke to this morning coming up.

[noelex 77]

One of the things I love about cruising is that I never need to set an alarm clock (well almost never) . Waking up slowly, in tune with your natural body rhythm, is a highly underrated pleasure.

This morning my Mermaid woke me just on dawn with the dreaded words "There is a boat dragging down on us". That woke me up quicker than any alarm clock .

It was the small yacht with the Fortress. Although the wind was only in the low 20's, there had been a 180° wind shift overnight and the Fortress had obviously let go.

The crew of the little yacht did a great job. One problem I have observed with the Fortress is that if it releases, the light weight and flat design offer very little resistance and the resulting drag is often very rapid. The light wind and long initial distance between our boats was the saving factor.

By the time I scrambled to the front with a boat hook and foghorn in hand, they had the engine started and things under control. The closest they came was about a boat length.

My Mermaid was getting fenders ready, but grabbed her iPad and snapped this photo as they motored away to reanchor. You can just see me standing guard at the bow with the boat hook:




This was the photo we took of their boat while diving on their anchor yesterday. It gives some idea of their starting position, although the wide angle perspective makes them look further from the beach than in reality:




In my view, the Fortress or any of the similar Danforth type designs are not suitable for overnight anchoring where there is any risk of the anchor undergoing a change in the direction of pull. This style of anchor has great holding power in softer substrates providing the direction of force is reasonably constant, however, in my opinion they are not reliable enough if there is a significant change in the direction of pull.

These owners nearly paid the price. I doubt such a small boat would have caused much damage to our thick aluminium hull, but I don't think they would have faired as well. Despite the light wind they were dragging at some speed.

[Fortress]

Originally Posted by noelex 77

This was a small, near new Fortress. An FX-11. It was dropped by a small private yacht. They stayed overnight.

The anchor was dropped closer to the beach where the substrate was better, in 4m @ 6:1 (but half the rode was rope).

Unfortunately, they did not set the anchor directly down wind and so the anchor was forced to rotate about 40° to the prevailing wind direction shortly after it was set. You can see it has developed a high list, although it was not set with much force to begin with.

This is clearly the case. I suspect that the small yacht owner set this 7lb (3kg) anchor using the "deploy and drink" method, where they dropped the anchor overboard, payed out the rode, then gave the anchor a gentle tug, and began consuming adult beverages.