Dragging of anchors

[Ian_Edwards]

My previous boat (40' 8 tonnes) came with a 15kg Delta, I had problems with this setting 1st time. We also dragged a few time, always in soft mud (including the inner part of Rona).
Replaced it with a 20kk Rocna, the most noticeable difference was that it set immediately, every time, with a "snatch" which dipped the bow. About 400 night at anchor and no dragging.
My current boat (46' 15 tonnes) it came with a 15kg Delta, it didn't even try using it, but replaced it with a 20kg Spade, the biggest anchor that would fit in the locker. I'd have liked a 25kg Rocna or Spade.
3 years on and about 350 nights at anchor, I've dragged twice:
1) In Loch Aline, soft mud and 50 knots of wind, 40m of 10mm chain in 10m of water, a slow drag, not much more than 2 or 3m per hour. I reset with 60m of chain and it held OK. In the morning (after the gale had blown through) someone had anchored up wind of me and was lying over my anchors, probably wasn't expecting me to have 60m of chain out.
2) Rona again, I reset in the outer harbour, 50m of chain in about 12m of water.
Both boats had 10mm all chain rodes.

 

[geem]

We had a 25kg Rocna on our 19 tonne yacht. Trident now has that anchor on his Cat. We moved up to 30kg Spade. The Rocna never dragged once set but we had a couple of drags whilst setting in weed. The Spade has not dragged once when set apart from when I managed to get chain around the anchor whilst it was gusting 40 knots. Very happy with the Spade and I am sure we would have been very happy with a larger Rocna but the Spade came up at the right time at the right price.
For windy anchorages to ensure a good nights sleep we usually put out a second anchor. This is a large aluminium Fortress type (came off a landing craft and was military green when we bought it for £40 at a boat jumble) set on just rope. Easily deployed from rib so no hassle to set. This has never dragged

 

[sailaboutvic]

We anchor for nine months each year, other than the odd day on a quay.

A question for you Jonathan

Have you ever sat with two anchors and if so, in which way do you have them, IE fork Or do you attached the anchors in line one in front of the other and if you do , do you back them has you lay them ?

I ask has The question because there have been a few times when I knew we was in for a very big blow, like now.
The Co skipper is away so I a solo the forecaster is for 40 plus kts blow for the next few days, I think it may be a lot more.
Mr Rocna has sat Nicely over the last few days and I expect it to be well in,
The winds have been blowing at time 25 kts , but just so I am guaranteed to sleep well the next two nights I have laid out my fortress too.

Last time I did this two other yacht came over and asked me why, they both when on to say there have dived on their anchor and mine and they are all set. One of the other yachts drag that night. So the lesson learned , if I think we in for a big one, for the sake of a few mins out goes my other anchor .
Of coarse in the wrong condition this can become a problem of its own, if the wind isn't going to be from the same direction over that time and two anchors are laid as a fork, then the rode will end up being entangled with each other.

 

[Neeves]

We anchor for nine months each year, other than the odd day on a quay.

A question for you Jonathan

Have you ever sat with two anchors and if so, in which way do you have them, IE fork Or do you attached the anchors in line one in front of the other and if you do , do you back them has you lay them ?

I ask has The question because there have been a few times when I knew we was in for a very big blow, like now.
The Co skipper is away so I a solo the forecaster is for 40 plus kts blow for the next few days, I think it may be a lot more.
Mr Rocna has sat Nicely over the last few days and I expect it to be well in,
The winds have been blowing at time 25 kts , but just so I am guaranteed to sleep well the next two nights I have laid out my fortress too.

Last time I did this two other yacht came over and asked me why, they both when on to say there have dived on their anchor and mine and they are all set. One of the other yachts drag that night. So the lesson learned , if I think we in for a big one, for the sake of a few mins out goes my other anchor .
Of coarse in the wrong condition this can become a problem of its own, if the wind isn't going to be from the same direction over that time and two anchors are laid as a fork, then the rode will end up being entangled with each other.

We often use 2 anchors.

We sail where 50 knot storms will occur on every cruise, somewhere in our cruising area experiences 25 knots every day - and of course the winds can be in between. However our winds are fairly predictable, they come in from the SW and veer to the SE and then ease. The timings might be a bit out, the speed might be a bit out but the general direction is reliable. Obviously when a storm is forecast we aim for the best shelter possible but sometimes its not as good as we would like.

We would lay 2 anchors as a 'V' really good scope. It depends on when all this happening but we would tend to lay the anchor that's on the bow roller, which is steel, and then lay a second anchor. The second anchors are all alloy (and all demountable) and we can lay from a dinghy or motor the yacht forward (and sideways). Our second rode is nylon and chain. If the wind is 'only' going to be 30 knots we would be comfortable with only one anchor but we would have a second anchor on the bow with its rode neatly coiled in a milk crate. We'ed deploy the second anchor at arond 30 knots, not becuase we need it but its a bit late in stronger windspeeds.

We cannot recommend a tandem set up. its very complex to deploy and equally complex to retreive. It is impossible to know if both anchors are actually set, or if one might have caught some seaweed (a common problem of dragging based on what everyone here is posting). The most damning point is that if the furthest away anchor sets then there is every chance that the anchor 'in the middle' will be lifted by the straightening of the chain (and then you just have a monster kellet). Some work on this has been done by a colleague at Practical Sailor but its not yet published and I only know the bare bones of the results.

Because we carry alloy anchors weight is not major issue and because they are demountable they are relatively easy to store. We are great fans of alloy - we would have an alloy primary but we already have a steel model and we are not going to throw it away - so it sits on the bow roller. We would tend choose the second anchor based on how applicable it was for the seabed, so a fluke anchor for sand and mud and one of the others if there was a chance of weed or pebbles.

Now whether we actually need 2 anchors (at 50 knots) - we simply do not know and other than sitting out a 50 knot storm on one anchor will not know - and its not a situation we have thought meritted an investigation (as if we do need 2 its a bit difficult to retreive the situation).

edit Someone will say - why bother with the second anchor and not have a monster primary. Its not much of a problem to deploy and if a stor is forecast you are not doing anything else - just sitting tight. There is no need to have a monster anchor on the bow roller most of the time - its simply weight in the wrong place and if its the wrong sort of anchor for the seabed it is very difficult to change. We anchor in seabeds that are big loose rocks, just the sort to get caught in a roll bar design. We anchor in thin mud, just where most anchors will not work. We anchor in thin weed, just the sort of seabed to clog some anchors. We have a cross section of anchors that we can swap and change for the seabed and at 15 and 8 kg is not a big issue. But swapping a 30kg model for another 30 kg model would be difficult. close edit

But our anchors are 15kg steel, or their alloy equivalents, so around 8kgs. The anchors are all efficient, or modern. Our cat has the windage of a Bav 45 though we only weigh in at 7t against the Bav's 12t.

We use a bridle based on 11mm climbing rope, the bridle is about 12m long. To manage the length we run it from the transom cleats, down the sidedecks and through turning blocks we attached to padeyes on the bow. We would never, ever, anchor without attaching the bridle. Climbing rope is a bit more elastic than nylon.

Jonathan

 

[Neeves]

One thing that does strike - and it leads on from my rhetorical question - do we need to deploy 2 anchors - some of the anchors being used would be considered small and certainly not overly large for the size of yacht but owners are finding them satisfactory.

Jonathan

 

[Neeves]

For those of you who are interested, and this is a bit of thread drift, in the next 4 weeks or so we will be having 75m of 6mm High Tensile chain galvanised, along with matching connectors (the connectors match for both size, a big issue, and strength) to replace our 8mm chain. We have run some small trials and we are able to galvanise the chain and achieve strengths higher than our current chain. Costings, here, are about the same gal 6mm HT is about the same as gal 8mm G30. Its something that could be done by anyone, in the UK - buy the chain, have it coated. We will need to buy a new gypsy but the chain is compatible with standard gypsies - and there is nothing special about the chain - its bog standard lifting chain. We are having an extra 15m galvanised for our second rode. Lightweight chain in a second rode becomes a real advantage if you row your second anchor out (I don't know - but especially if you would normally use 12mm chain as you could at least downsize, safely, to 10mm)

I'll comment on the trials at the back end of the year, by which time I'll have tested the chain for strength and used it a few times, but its part of our desire to have light ground tackle. In theory it should all work - but obviously we will not know until we actually try it - anchoring is still not quantified such that it is 100% predictable.

Jonathan

 

[sailaboutvic]

Hi Jonathan
Thank for that interesting bit of info.
It's 08.30 here in Greece, last night the wind did has predicted, and quite a swell worked its way into the anchorage, there with some rises voices during the night and I see this morning two of the boats are no longer where they were last night ,

Our second anchor a fortress did its job, they were set has an fork,
it helps me to sleep without the stress that we might drag, a bit of an insurance policy if you like, especially has I am solo over the next few days,
Dealing with a dragging anchor in high wind isn't any fun, I can tell you from past experiences.
That's not to say that Mr Rocna wouldn't have done the job on its own,
I have tried a combination of anchoring in the past and have experimented with connection three meters of 8mm chain on its crown, With the second anchor off that, a tripping line was then taken of the first anchor so it can be controlled and easily lifted back on board.
You don't want a anchor dangling in mid air banging on the hull.
The trick here is to make sure that the second anchor or the chain doesn't fall on the first so the boat has to be very, very slowly going backwards, Given them both time to settle before increasing the power at a slow rate .
Each time I have done this I have found one anchor well in and the other just biting, which makes me think that if enough pressure was increased on the rode the second anchor would then also set.
This was done with an alloy fortress in front and my old Delta behind, I have not tried this with my Rocna.also on a good sea bottom ,
On weed it may be a very different story .
I have to agree with you there is a chance that one might not set or just get caught up and unless one dives they wouldn't know.
The wind has drop some what now but it forecaster to return later to day and continue
Thought Out the day and to night , so I very happy sitting this one out knowing that I am in good hands with my fortress and Ronca to keep me safe .

 

[sailaboutvic]

One thing that does strike - and it leads on from my rhetorical question - do we need to deploy 2 anchors - some of the anchors being used would be considered small and certainly not overly large for the size of yacht but owners are finding them satisfactory.

Jonathan

Just to comment on this.

They're anchoring and anchoring has we all know very well.
Are these people who are advocating the use of small anchors that work anchoring in high winds at time with swell?
Taking last night for an example, I have to wonder why them yacht dragged when so many other didn't,
Where their anchors suitable for the size of their boats?
Or were they just unlucky?
Some weeks back boats in Corfu and Paxoi had a very bad time, getting caught out in a storm that came from nowhere.
Some yacht dragged the unlucky ones were beached while some sunk.
But also a lot held.
So were some of them yacht anchored to smaller for the size of boat ?
Just bad anchoring and not enough scope ?
Or just unlucky ?
I guess we will never know.

 

[Neeves]

Hi Sailaboutvic,

More info on tandem anchoring - if the 2 anchors are too close together, as you suggest, then the far way anchor simply 'ploughs' or sets into the loosened seabed and furrow of the closer anchor. You really need to separate them as much as possible. The other aspect is that the closer anchor, to the yacht, must have a hole at the bottom of the shank, where it joins the fluke. Most anchors have a hole but this is simply a hole to attach a tripping line and is 'too high' to use for a tandem. A Rocna has such a hole (or did do) near the fluke, (as well as a tripping hole) but many anchors do not. With your set up you would have the Fortress as the outer, further away anchor, and the Rocna closer in, nearer the yacht.

But I'd stick with the 'V'.

One advantage of the 'V' is that it helps steady the yacht (like a bridle) and a steady yacht, one not veering, is reducing snatch loads. its the snatch loads that contribute to dragging in non modern anchors. A tandem is just one line and you will veer as much with a tandem as you do with one anchor. I think the major addition to most rodes is elasticity, a snubber, but it needs to be about 10m, longer if possible, of thin nylon, say 10mm for a 35' maybe 12mm for a 45' yacht. If the snubber is not long enough it cannot absorb the energy of the moving yacht - some of the energy is passed to the chain (and your anchor). Most second rodes, unless you have 2 windlass and twin bow rollers, are mixed (nylon+chain) - but you still need a snubber (2 to make a bridle for a big yacht) on the all chain rode. If these snubbers seem thin - they are meant to be. They are consumables and if they are hefty they simply do not stretch. Think of a bungy jumper - all the energy of their fall is absorbed by the bungy chord - your yacht is the 'jumper'. If the bungy chord were replaced by chain?! - but that is what most yachts have, all chain.

Sorry for the thread drift.

Jonathan

 

[Neeves]

Just to comment on this.

They're anchoring and anchoring has we all know very well.
Are these people who are advocating the use of small anchors that work anchoring in high winds at time with swell?
Taking last night for an example, I have to wonder why them yacht dragged when so many other didn't,
Where their anchors suitable for the size of their boats?
Or were they just unlucky?
Some weeks back boats in Corfu and Paxoi had a very bad time, getting caught out in a storm that came from nowhere.
Some yacht dragged the unlucky ones were beached while some sunk.
But also a lot held.
So were some of them yacht anchored to smaller for the size of boat ?
Just bad anchoring and not enough scope ?
Or just unlucky ?
I guess we will never know.

It would be interesting to get any information.

To me a well set anchor is one you cannot see that has buried itself and a few metres of chain into the seabed. Buried chain adds to holding capacity, or does do according to the US Navy - and I'm not arguing with them. Large anchors are difficult to set deeply consequently the chain sits on the seabed and is not buried. Any movement of the yacht (through swell) has more chance of impacting the anchor thats poorly set than an anchor that is deeply set (and well dived).

Many of the anchorages we use in new South Wales are 'Ocean anchorages' simply large bays sheltered from the prevailing wind but not sheltered from swell (of the Tasman) and on Tasmania's west coast, the Southern Ocean. Swell is not an issue they are not sharp impacts, but seas, locally formed, might be more of an issue.

But we know our anchor is parsimonious and we anchor with care and try to do it properly every time. Maybe if we had a big anchor we might be a bit less careful - after all if the anchor is twice the size it should be maybe it breeds complacanacy.

Its all very complicated

What is surprising about this thread is that many of the people posting are cruising quite challenging cruising grounds, Scotlands west coast. I deduce they anchor a lot (as there are few marinas) so they are describing tougher than average anchoring conditions and some are using pretty standard sized anchors. The west coast of Scotland is not renowned for balmy weather (or wasn't when I lived there) and if small was bad - its not coming through.

I don't argue with the idea 'no-one complains their anchor is too big when its blowing 50 knots' - but that does not mean they need the bigger anchor.

But I think luck comes into it - but also (read the thread on 'why can people not anchor') the Med attracts neophytes.

Jonathan

 

[CAPTAIN FANTASTIC]

My cqr was unpredictable, it was either very good or very bad depending on sea bed type and other variables. My big claw was good but a bit fussy on sea bed type. My current "modern" convex with a very long balanced tip, its more reliable and so far will dig in straight away and is not fussy on the type of sea bed, although I have not tried it on stone/gravel sea bed. An anchor watch alarm in high winds is a must for me.

 

[Neeves]

This made me realise I should have mentioned the Kobra (and Ultra) as modern anchors.

Jonathan

 

[sailaboutvic]

{But I think luck comes into it - but also (read the thread on 'why can people not anchor') the Med attracts neophytes.}

Well I can't disagree with that , when it come to the Ionian .

South of France, Sardinia , Croatia , Aegean is another story .

 

[Dockhead]

My views on this have evolved over the years.

I don't think any anchor should drag if it's properly set and the sea bed is reasonable.

I learned bad anchoring technique from my Father using crappy CQRs and claws - he didn't believe in backing down hard because - now get this - you might pull the anchor out! We dragged a lot

Then we bought one of the first Spades, which tolerated our poor technique much better.

Since then I've had Deltas, Rocnas, and another Spade on various boats.

Nowadays I spend 15-20 minutes or even more working the anchor into the seabed. At the end I use full power in reverse for at least 3 minutes, and if the anchor moves at all, I pull it up and start over. It's been 12 years since the last time I dragged anchor.

The main difference between anchors, in my opinion, is how easy or hard they are to get a decent set, not how well they hold once set properly. I prefer Spades, as they are well balanced with the lead ballast, and seem to go in easier with their sharp tips. But I had pretty good luck with my Rocnas too, and even Deltas worked ok as long as you had enough patience getting them set.

 

[vyv_cox]

This made me realise I should have mentioned the Kobra (and Ultra) as modern anchors.

Jonathan

IMHO there is a considerable difference between a modern anchor and a new generation one. Whereas Kobra II has been designed in the past ten(?) years it offers no particular technical advance over a Delta that was designed 30(?) years ago, except possibly its shank shape that seems to have been derived from Spade and Oceane. Whereas the Ultra is technically advanced, benefiting from recent knowledge about tip loading, three dimensional shank construction, etc. There is no shortage of 'new' anchor designs but that does not automatically make them NG ones.

So far as dragging is concerned my experience with Delta for 20 years and Rocna for 10 is that, once set satisfactorily, neither has ever dragged other than in exceptional circumstances. These include being set in a huge bundle of fishing line enough to fill a full size bin liner, a tin can stuck over the point of the Rocna, a large rock jammed into the hoop of the same anchor and, quite recently, adverse experience with an Osculati swivel that would not lie straight in line with the shank but determinedly jammed repetitively and pointed downwards.

All our dragging experience has occurred when trying to get either type to set, due to various types of bottom - soft mud, hard sand, weed, rock that looked like sand, etc.

We also use a fork moor very successfully when conditions warrant. The fX16 Fortress used like this has never dragged although when launched from the tender it rarely sits flat on the bottom, always at an angle to it, which gives rise to unfounded concern when I dive on it. We find fork moor to be a very successful method in the common Mediterranean situation of heavy gusts coming off high cliffs, or down adjacent valleys, maybe at 90 degree variation. I also believe that tandem anchoring is vastly overrated and hope to prove that it is technically flawed in the near future.

 

[westernman]

We used to drag regularly with a brand name articulated plough, oddly we would drag under the most benign conditions and equally oddly it would hold in conditions when we thought it would definitely drag. It weighed in at around 20kg and we used it on our 38' cat.

Interesting that observation. I have a 75lb CQR on a 53ft 32 tonne boat (67ft if you include the bow sprit). It is sometimes a right PITA to set** - even in good anchorages. However, there have been times in really windy conditions where I have thought I would definitely drag (and have spent all night up just waiting ready to start the engine) where it has held.

Looking at Rocna's sizing chart, the recommended sized Rocna would be 88lbs, so I think the CQR is definitely on the small size for my boat. However, when conditions seem to be bad, it seems to hold very well indeed.

** for setting the Tom Cunliffe recommended approach seems to work best. Drop it over the side, gently reverse while paying out the chain, then have a cup of tea or two before trying to dig it in. It seems very reluctant to set if you try to dig it in right away (regardless how gentle I am trying to do it). The cup of tea approach has worked every time!!!

I suspect in conditions where there is a lot of wind (once you are dug in), in the end the only thing which really matters is the surface area of your anchor rather than the design. I think moving up a size or two has more effect than the design of the anchor.

However the new generation anchors are certainly better at setting, are much easier to get dug in in non ideal sea beds, and better at coping with changes in wind direction.

 

[Neeves]

Having tested the Kobra I have found it sets quickly and holds well in sand,edit better for both characteristics than the Delta. close edit It is let down, in my view, by its thin shank constructed with a steel of questionable quality (but then it is cheap)

Jonathan

 

[vyv_cox]

Having tested the Kobra I have found it sets quickly and holds well in sand,edit better for both characteristics than the Delta. close edit It is let down, in my view, by its thin shank constructed with a steel of questionable quality (but then it is cheap)

Jonathan

No argument from me there Jonathan but by my definition that doesn't make it a New Generation anchor. It's a plough, maybe with improved geometry, but still a plough.

See http://www.ybw.com/forums/showthread.php?432850-Oops&highlight=Oops!

 

[Neeves]

In starting the thread I had made the basic assumption that most anchors introduced, say, since 1990 were an improvement on those made prior and rather than use NG, which excluded Spade (and I suspect Ultra and Vulcan) I used 'modern' I have not checked recently and my memory might be at fault but NG was very restrictive. Frankly I do not care what an anchor looks like - and as I use something that looks superficially like a Delta but outperforms the Delta markedly this suggests to me there are nuances of design about which we know little. Maybe we should not categorise too quickly nor easily. A Jeep looks like a Discovery - but there are some subtle differences.

Most modern anchors I have tested,Rocna, Ultra, Spade, Excel, SARCA, Mantus, Kobra, Supreme outperform a Delta, Bruce (I have only tested the Claw and Ray) and CQR by a factor of 2 at least, in terms of holding capacity and speed of setting. Each of these anchors has been introduced since 1990. Delta I think was mid late 1980s. The exception is the Fortress, which also has enviable hold but I think was introduced prior 1990, late 1980s. I'm of the belief that most people blind fold could not tell the difference between those I define as 'Modern' but they could distinguish between modern and pre modern, Fortress excepted.

Sorry to belabour 'modern'

Jonathan

 

[jordanbasset]

Having tested the Kobra I have found it sets quickly and holds well in sand,edit better for both characteristics than the Delta. close edit It is let down, in my view, by its thin shank constructed with a steel of questionable quality (but then it is cheap)

Jonathan

Agree with you, we used our Kobra 2 all the way down to Greece from Plymouth. Anchored in some very strong winds and a variety of circumstances. Only dragged once, oh and the shank never bent either
We would certainly go with it again if we had an old style anchor on the boat, and would include a Delta in that

Interesting this person considers a Kobra a new generation anchor and the Delta old generation
http://www.mysailing.com.au/news/testing-the-new-generation-of-anchors
'Looking at the results we have a group of anchors — call them “old generation,” the CQR, Delta, and Bruce — that might have a holding capacity of 750kg for a 15kg anchor set properly in a good holding seabed. We have another group of anchors, the “new generation,” Fortress, Spade, Super SARCA, SARCA Excel, Manson Supreme and Kobra — that have a holding capacity of 1500kg for the same weighted 15kg anchor.'

Edit just realised that is your test, would like to commend you on a thorough piece of work, excellent