Big anchors

[geem]

Isn't the core question whether a part set (in sub optimal substrate) oversize anchor holds better than the correctly sized one? It's about relative holding part set in poor conditions.

It will depend on the substrate but it is the real world we operate in. If true, then a massive argument for over sizing.

I think it is more complex than that. If the anchor remains half set, but stable then it may actually fully bury itself and become fully set in rising wind. Alternatively, it may pull out of the seabed due to yawing, as in its half set position it is unstable. There are so many variables in seabed conditions that I don't think one answer covers all potential scenarios

 

[noelex]

Minor correction to your earlier post. There were three locations, as I said. They recorded results from the first twice. I am not sure why as I know they carried out dozens of tests in each location on every anchor. View attachment 159496

Thanks for the correction Vyv. So this test showed in two locations (not three) a 15kg Spade achieved an average holding power of 2500 kg and in the third an average of only 250 kg.

I think the take home message is that the substrate can produce a huge variation in the ultimate holding ability of an anchor. You may not need the higher ultimate holding power of a larger anchor frequently, but there will be times when it will be valuable.

One of the most common times when this extra ultimate holding power is beneficial is enabling you to safely use a substrate that would be unacceptable with a smaller anchor. The extra ultimate holding power of the larger anchor will result in holding power of some substrates crossing the threshold where an acceptable degree of ultimate holding power is achieved.

The other significant benefit that has not been mentioned in this thread is the use of shorter scopes than would be required with a smaller anchor. As the scope is decreased the ultimate holding power will also decrease. This reduction in ultimate holding ability can be compensated for replacing the anchor with a larger model that will have a higher ultimate holding power. Thus a larger anchor may have the same ultimate holding power at, for example, a scope of 3:1 as the smaller anchor (of the same design) has at 5:1.

These two advantages open up anchorages and anchor locations that would be unacceptable with a smaller anchor. This extra versatility in anchorage selection achieved with a larger anchor alone is worth the extra cost in my view, but as always YMMV.

I would also caution people to always select an anchor that can still be comfortably managed.

 

[srm]

Not many replies yet.....so no-one has dragged using a new gen anchor and you are all happy with the size...??

Jonathan

Is a genuine Bruce patent anchor counted as NG? Certainly it was the latest at the time described below, well before the proliferation of copies.

If so I was using an oversized 30Kg Bruce (42 ft classic sloop) on a generous all chain scope in a sheltered anchorage with usually good stiff mud holding on the west coast of Scotland. I did not like the forecast so also laid my second anchor, a 20Kg Bruce on a longer chain and nylon scope. Early in the morning we experienced the full force of the wind funeling between two islands. The anemometer was hard against the stop at 60knots for a couple of hours until the wind backed and we were again sheltered. I estimate we had winds in the 60 to 80 knot range. The hard dinghy astern capsized and acted as a drogue reducing yawing to the gusts. During a stronger gust we swung broadside on to the wind putting the lee rail under, then returned head to wind. From the rode layout when retrieving the anchors a couple of days later it looked as if the main anchor had dragged until the second took some of the load and checked the boat. Both anchors were well dug in on retrieval.

 

[noelex]

Precisely the kind of data I have asked for several times. The measure is hold achieved against load applied. So if I set my anchor using my engine I am applying between 250-300kgs. The size of anchor is irrelevant - the hold will be the same. This will continue as the load increases (the wind gets up) until the anchor drags - and both anchors will behave the same. The question then is whether the larger anchor will hold for higher loads.

It seems to be accepted that dragging is now rare, and when it does happen it is more likely to be because of the nature of the substrate , too little scope, poorly set etc rather than limitations of the ultimate holding capacity of the anchor

I don’t know why you think both anchors will behave the same. As we have established, the larger anchor will have a higher ultimate holding ability in any particular substrate than a smaller anchor (of the same design and constuction material).

As as the load increases (the wind gets up), as you indicated, the load will cross the threshold where the smaller anchor no longer has sufficient ultimate holding power in that substrate and it will start to drag.

The ultimate holding power of the anchor is not the same as the setting force. The setting force is only a light load (usually equivalent to about 25-30 knots of wind if you set agressively ). Even a small anchor should (hopefully) be capable of holding a much higher force than this. As the wind increases, the force will rise above the setting force and the anchor will dive deeper until its ultimate holding ability for that substrate is reached, when it will start to drag.

The larger anchor will be able to hold at this same load, as its ultimate holding ability in the same substrate is higher. It will hold the boat until (if the wind picks up further) the ultimate holding power of the larger anchor is exceeded.

I have tried to explain this same concept in different ways several times in this thread in response to your questions. Perhaps my explanation is poor but if the above does not make sense perhaps we need to agree to disagree on this point.

 

[geem]

I don’t know why you think both anchors will behave the same. As we have established, the larger anchor will have a higher ultimate holding ability in any particular substrate than a smaller anchor (of the same design and constuction material).

As as the load increases (the wind gets up), as you indicated, the load will cross the threshold where the smaller anchor no longer has sufficient ultimate holding power in that substrate and it will start to drag.

The ultimate holding power of the anchor is not the same as the setting force. The setting force is only a light load (usually equivalent to about 25-30 knots of wind). Even a small anchor should (hopefully) be capable of holding a much higher force than this. As the wind increases, the force will rise above the setting force and the anchor will dive deeper until its ultimate holding ability for that substrate is reached, when it will start to drag.

The larger anchor will be able to hold at this same load, as its ultimate holding ability in the same substrate is higher. It will hold the boat until (if the wind picks up further) the ultimate holding power of the larger anchor is exceeded.

I have tried to explain this same concept in different ways several times in this thread in response to your questions. Perhaps my explanation is poor but if the above does not make sense perhaps we need to agree to disagree on this point.

I think this thread is now just going around in circles. There have been some very good responses as to why an over sized anchor is not the be all and end all. There are many variables that influence a good hold, not just size.
I think a take home, for me, from this thread is that power setting my anchor to maximum revs every time will ensure the anchor is set. We have been doing this often, but not every time.
Once our Spade anchor is set is doesn't drag. With no roll bar it sets deeply. With several days of wind gusting into the 30s, it keeps setting more deeply, unhindered by a roll bar. When we recover it, even with the chain vertically above the anchor, the 1700w windlass will often stall, unable to break out the anchor. The bow has often dipped at least a foot due to the power of the windlass pulling the boat towards the anchor vertically. At that point, we stop lifting with the windlass and drive forward on the engine. This is the only way to break out the anchor. I think I am happy with my anchor selection from the manufacturer’s chart

 

[Tranona]

I don’t know why you think both anchors will behave the same. As we have established, the larger anchor will have a higher ultimate holding ability in any particular substrate than a smaller anchor (of the same design and constuction material).

As as the load increases (the wind gets up), as you indicated, the load will cross the threshold where the smaller anchor no longer has sufficient ultimate holding power in that substrate and it will start to drag.

The ultimate holding power of the anchor is not the same as the setting force. The setting force is only a light load (usually equivalent to about 25-30 knots of wind if you set agressively ). Even a small anchor should (hopefully) be capable of holding a much higher force than this. As the wind increases, the force will rise above the setting force and the anchor will dive deeper until its ultimate holding ability for that substrate is reached, when it will start to drag.

The larger anchor will be able to hold at this same load, as its ultimate holding ability in the same substrate is higher. It will hold the boat until (if the wind picks up further) the ultimate holding power of the larger anchor is exceeded.

I have tried to explain this same concept in different ways several times in this thread in response to your questions. Perhaps my explanation is poor but if the above does not make sense perhaps we need to agree to disagree on this point.

I do follow your argument, but given the low incidence of dragging , or rather the lack of reports of dragging with NG anchors it seems that NG anchors are already "oversized" in the sense that their potential holding power is far greater than can ever be exploited. Remember the oversizing is going up a size say from a 15kg with a holding power of 2000kgs to a 20kg with nearly 3000kgs, NOT from 6kg to 15kg which you use as an example. Given that it is well established that the load of a typical 35-45' boat even in extreme storm conditions does not exceed 1000kgs it is not unreasonable to assume that failure to hold is not because the anchor is too small but because the substrate cannot hold that force. That is why I would like to see the correlation between hold and load to show that at the loads we are talking about (which are nowhere near the ultimate) failure will occur at the same point irrespective of size..

 

[Neeves]

Thanks for the correction Vyv. So this test showed in two locations (not three) a 15kg Spade achieved an average holding power of 2500 kg and in the third an average of only 250 kg.

So you set your 15kg Spade in an anchorage expecting 50 knot winds. You power set, say to 300kg - the anchor drags beyond 250kg. You know you will be subject to 50 knot winds - exactly how big a Spade would you need to oversize by to offer security?

The answer is surely to choose an anchor that is suitable for the seabed, not carry a 45kg model - just in case.

If you anchor with a short scope the disadvantage is that you will be subject to snatch loads (reducing the holding capacity of your anchor). The elasticity of your snubber will completely replace the catenary effects you have lost - and its lighter and cheaper than buying a bigger anchor.

And here is the data. The calculations are based on 5:1 but you can extrapolate and understanding the advantages is easy. And it does not matter how strong the wind is - the nylon will continue to replace the effects of catenary. The data is also on the basis of all chain 5:1 and all nylon, same depth as the 5:1 scope. In real life you would use a combination of snubber and chain.



If we calculate, 5:1 scope and 30m of chain this then implies 6m from bow roller to seabed. A 'short' scope might be ... 3:1 which would be deployment of 18m of chain. So.... you can have a deployment of 18m of chain at 3:1 + the same 10m of 10mm nylon and the nylon will give you better reduction of snatch loads than with 10mm chain deployed at 5:1 (because the nylon stretches and absorbs the snatch loads much better than the all chain 5:1 scope).

The death of fears of short scope.

And no more hold reduction due to short scope - it can be consigned to history along with the 'Bigger is Better' mantra.

Now personally I think 10mm nylon a bit skinny for a yacht carrying 10mm chain - I'd use 12mm nylon and more of it (run it down the sidedeck - no need to be all forward of the bow, you could have 10m down the deck and 10m forward of the bow - but I'm being picky).

Jonathan

 

[Neeves]

I have tried to explain this same concept in different ways several times in this thread in response to your questions. Perhaps my explanation is poor but if the above does not make sense perhaps we need to agree to disagree on this point.

The hold of a 15kg anchor is around 2,000kg. The hold of a 25kg anchor will be about 3,000kg. A 15kg anchor might be recommended for a 35' yacht. It is unlikely that the 35' yacht will ever be subject to a tension in the rode beyond around 500kg - at a higher tension the issue might not be the anchor but the strength of the bow roller and if we get to the tensions of the ultimate hold of the 15kg anchor the chain and shackle will be deforming (and the chain would be unusable - it will no longer fit the gypsy).

Why carry the 25kg anchor when you will never exceed the hold of the 15kg anchor.

You could of course use bigger chain (as well as the big anchor) - but 12mm chain would look a bit silly on a 35' yacht - and the weight of the rode would totally destroy its sailing performance. But Hey! - you would able to say 'Noelex is right!' -'just a pity I had to spend so much on a bigger windlass.....'

Now say you are anchored in soupy mud - the hold of your 15kg anchor will be inadequate (totally), in fact the hold of the 25kg anchor will also be inadequate - so you get out your Fortress and use that instead - it will hold you securely (and is why you carry the Fortress).

The reason 'we don't understand' is because you have no data to back up your contentions, you have totally unrealistic arguments and you totally ignore the posts pointing out the error of your ways. There is a strong body of opinion, based on evidence, experiments and real life, posted by Geem, Vyv, Tranona, Thinwater (and others) to simply name a few. You completely ignore what they say and continue to repeat the same old mantra without a shred of evidence and virtually no support.

The biggest danger I see is that you will continue to post your dangerous fairy tales and some poor unsuspecting novice will believe you and spend good money unnecessarily - money that could have been invested in a decent snubber (for a paltry amount). This thread is not the only example of you blindly projecting a view that is undermined by evidence (but I'm unable to be more specific for fear of banishment)..

Jonathan

 

[Neeves]

I think this thread is now just going around in circles. There have been some very good responses as to why an over sized anchor is not the be all and end all. There are many variables that influence a good hold, not just size.

The majority of people inhabiting this thread either think the idea that 'bigger is better' lacks any quantitative support or they are ambivalent (and not strongly supportive (of BisB). There is only one vociferous supporter and his arguments have not been supported by any data, nor many people.

Most people seem to vote with their feet and wallets and buy the recommended size or if their location on the spreadsheet (is on the limits) buy one size bigger.

In general modern new gen anchors have an excellent safety record, maybe with some exceptions, see below. We are lucky to live at a time of some reliability and predictability. The exceptions would be choose your ground tackle with care and/or check the testing - some excellent anchors do not perform too well in specific seabeds, soupy mud, weed - much of this has nothing to do with size - but design. Power set, as you say, use a good snubber and don't be complacent.

Jonathan

 

[doug748]

Yes. It turns on poor and unreliable seabed conditions

We just await evidence that that a larger anchor will perform less well than an undersized one, in poor ground, and all will be one.

Soon be Christmas.

.

 

[Neeves]

Yes. It turns on poor and unreliable seabed conditions

We just await evidence that that a larger anchor will perform less well than an undersized one, in poor ground, and all will be one.

Soon be Christmas.

.

Sighs in background, wrings hands.

No - one has mentioned undersized anchors.

the evidence required is NOT as you suggest - you seem to misunderstand (not unusual in this thread).

To justifying buying and carrying the larger anchor (of the same design) than an anchor of the recommended size the larger anchor MUST perform BETTER than the anchor of the recommended size (in ALL seabeds) when deployed from the same yacht and using the same rode etc etc. As you say - we await evidence. If the larger anchor cannot be shown (evidence required) to be BETTER - you would be better spending that money on a decent case of malt whisky .....

adds to his stock of whisky futures.

Its a sure bet.

Evidence ..... Hope springs eternal..... or .. dreams are free

Jonathan

I have checked - NASA have seen no flying pigs



It is strange that given the passion of the Bigger is Better disciples and the length of time this debate has run, years (and more years) they have been demonstrably unable to coral any evidence, at all.

 

[Tranona]

It is strange that given the passion of the Bigger is Better disciples and the length of time this debate has run, years (and more years) they have been demonstrably unable to coral any evidence, at all.

No different from any other belief. Supporters challenge you to name something that cannot (or has not) been proved - or at least demonstrated to have possible validity.

BTW corral has 2 "r" s to mean what you want it to mean.

As a matter of fact there has been mention of potential undersized anchors - post#53 offers data showing that a 15kg anchor can develop a higher hold than a 6kg of the same deign - but fails to say which was the recommended size for the boat in question. This ignores the central distinction that underpins the comparative rather than (absolute) term "oversize".

 

[thinwater]

View attachment 159496

If the holding capacity varies this much (and I could post a different test that would show just as much scatter and a different ranking, how do we define what "oversize" is?

• Anchor test data is like herding cats. There is 300% variability within every anchor, and we're arguing over 30% increments.
• Every manufacture has a different idea of what normal bottoms are.
• Every manufacturer has a different safety factor in mind.
• Do we rank by maximum hold, greatest average, or greatest minimum? By the latter standard (which makes a lot of sense to me), Manson Supreme wins this test and Delta looks better than Spade.
• You could go by what you see at boat shows (tiny Deltas).

In the end, we go by the local scuttlebutt, weighted by the word of cruisers we think have experience. Interestingly, Panope rated the CQR pretty good, this test does not, many users swear by them, many more swear at them, and I think they are all telling the true as they've seen it. This is why I avoid anchor testing that involves testing brands, and why I focused on methods.

I've actually tested anchoring with a full sized NG anchor (no names--I did this with two different brands), and then got it to drag by anchoring at 5:1 scope and setting the boat up to yaw (skipped the bridle and adjusted the windage). I then set up the bridle and snubber, downsized the anchor 10x, and spent the night (only one brand--the other was not available smaller). The method made more difference than a 10x larger anchor. Interesting.

I use what would be consider normal size on my cruising boat and 1-2 sizes down on my overnight/sport boat. So far, no dragging. If the mud is very soft I use long scope, long snubber, set the anchor in stages, and set up for minimum yawing. Not having a windlass on the sport boat, it's nice having an anchor that weighs less than a bottle of milk. My cruising boat has chain and a windlass, and yes, that anchor will break toes.

 

[Tranona]

Lot of sense there. One of the downsides of the high load tests is that they tend to choose seabeds that will stand high loads (otherwise how do you establish maximum hold?), although some try to find different conditions that might show up different rankings between different designs. However what is clear is that NG anchors in general develop much greater usable holding power - that is they set more easily and withstand changes in load direction and level better. More importantly the potential hold is far greater than the load a boat of the size for which it is recommended can ever generate. This is further endorsed by the wide range of boat sizes for each size of anchor. For example for the Epsilon a 16kg covers from 32 to 45', the level of suitability (as indicated by shading) falling from 40' upwards.

From this, both the test data and the recommendation, one can only conclude that there is massive reserve of potential hold and the limitation for actually using it, assuming the same boat and load, is the seabed, not the size of the anchor. For me the question has always been what is the marginal benefit of having a larger anchor (or a larger chain size) over the size recommended or tested to have sufficient reserve in the case of chain. This of course depends on the specifics of the boat and where it sits on the continuum of the recommended range of boat sizes,

My boat is nominally 31' which is firmly in the middle of the 10kg range and below the minimum size for the 16kg and I usually anchor in seabeds that are similar to those used in the maximum hold tests so am quite happy with 10kg. However It is also clear that performance of different designs can vary according to seabed. Others might take a view that because the range for the next size up (16kg) starts at 32' they would prefer to buy the larger size. This, as in all marginal decisions is a matter of judgement based on your experience, and my experience led me to my decision.

This does not resolve the "bigger is better" argument with regard to anchors as unlike chain there is not an independent way of testing the marginal difference between sizes other than possibly comparing immersed fluke areas. Hence my request for evidence in the way of hold against constant loads for recommended and next size up of the same design of anchor in the same seabed. Anecdote and observation suggests there would be no difference, but it would be nice to have some empirical data - even if only to have something new to debate.

 

[Neeves]

Ignoring size (and introducing a bit of drift) I have learnt that evaluation of anchors is a very long process. Hidden features become more obvious with time.

It took me years, literally, to define the characteristics of the Mantus M1 in the same way the 'weakness' of Rocna, clogging, took years to come to the fore. I am a believer in Spade but do wish they had found a way to sharpen the toe. Ultra found a way to beef up the hollow shank of their anchor - again I wish Spade had done the same with their aluminium anchor.

Thinwater's work on yawing put a focus on depth of set, or ease with which an owner can engender a deep set (more time at higher engine revs, don't be complacent) and put focus on shallow set anchors. Geem's observation of his hand set Fortress is another example of a valuable observation. Viking's extended use of HT steels (high lit by Peter Smith's use of HT steels - and the furore) opens a new door for anchor makers - that has been largely ignored. But Viking offers to me, and those who want a lightweight anchor that performs, a choice beyond aluminium (we could have a lightweight steel Danforth type, or a lightweight Bruce). What Fortress, Spade and Viking taught me is that lightweight anchors are reliable.

With time we have learnt about Rocna, time will also expose weaknesses in other anchors - currently hidden (and maybe unimportant). There may be features of Viking or Epsilon - so far hidden that detract. I don't know but reports on forum, here, more testing will offer new windows on performance.

There is plenty of opportunity to enjoy further anchor threads - that hopefully are as educational as this one initiated by Geem.


I make repetitive comment on Vikings use of HT steels. We can thank, maybe, the automotive industry for the opportunity to use such steels in anchors. Historically it was difficult to make thin HT steels in sheets flat enough to meet the specifications of the automobile industry. Such steels are now more commonplace in high end vehicles, cranes and road trailers (say for containers). 3mm HT steels were simply not available (maybe thinner - I'm not an anchor maker, I don't need to know) - now you can buy them in flat sheet, off the shelf.

Jonathan

Even though I'm not an anchor maker I had a quick and superficial look - you can source 2mm plate with a min yield strength of 900MPa. Designing a lightweight 'Danforth' type (or any other design), stronger and lighter than a Fortress would be quite feasible. Check SSAB website - there may be other steel manufacturers with similar, or better, qualities. As with BIS80, or any other Q&T steel you would lose some strength when you galvanise.

 

[GHA]

It seems to be accepted that dragging is now rare,

Who told you that? Happens all the time. Getting near August when Europe takes a month off & it's drag racing time. Experienced cruisers will be anchored up wind. In Culatra pretty much every day when the wind goes up to about 25kts every afternoon there will be boats dragging. Maybe not in your neck of the woods where most run back to the mooring or marine if the forecast gets up. Textbook conformation bias.
Lets face it, these threads are storm in a teacup, people don't generally upsize. Apart from long term full time cruisers who very often will. With no real downside, just year in year out uncertainty, can`t trust the weather, the bottom, being able to get as much scope as you like. Bit bigger puts the odds a bit more in favour of you home staying where you want it to be. It's like god of the gaps, point out an argument doesn't hold up in the real world & someone will run around to find another one. You don't size a hook by engine size, bit of slack & get a load of way on in reverse. Been a common practice by many for years. It works.
And few sailors pay too much attention to rants on the web anyway, forums & are generally viewed somewhere between hilarity & incredulity. crusty cruisers with heavy duty anchoring systems tried & tested over the years having a sundown in some shack on a beach somewhere would fall on the floor laughing at some journo ranting page after page telling them they were doing it all wrong.
Pity really, absolutely no point on posting a thread even mentioning anchor now, it gets derailed straight away into opinionated rants with no chance of seeing any middle ground.

 

[Tranona]

Who told you that? Happens all the time. Getting near August when Europe takes a month off & it's drag racing time. Experienced cruisers will be anchored up wind. In Culatra pretty much every day when the wind goes up to about 25kts every afternoon there will be boats dragging. Maybe not in your neck of the woods where most run back to the mooring or marine if the forecast gets up. Textbook conformation bias.
Lets face it, these threads are storm in a teacup, people don't generally upsize. Apart from long term full time cruisers who very often will. With no real downside, just year in year out uncertainty, can`t trust the weather, the bottom, being able to get as much scope as you like. Bit bigger puts the odds a bit more in favour of you home staying where you want it to be. It's like god of the gaps, point out an argument doesn't hold up in the real world & someone will run around to find another one. You don't size a hook by engine size, bit of slack & get a load of way on in reverse. Been a common practice by many for years. It works.
And few sailors pay too much attention to rants on the web anyway, forums & are generally viewed somewhere between hilarity & incredulity. crusty cruisers with heavy duty anchoring systems tried & tested over the years having a sundown in some shack on a beach somewhere would fall on the floor laughing at some journo ranting page after page telling them they were doing it all wrong.
Pity really, absolutely no point on posting a thread even mentioning anchor now, it gets derailed straight away into opinionated rants with no chance of seeing any middle ground.

Helps to read the comments in context rather than taking them out of context. This thread is about whether an anchor one size up than recommended is "better" at resisting drag than the recommended size. The comment about dragging seeming to be rare was in the context of today's much improved designs. Was never intended to mean that dragging does not happen at all. The problem with examples like yours is that they lack explanation as to why the anchors drag. Nothing about what sort of anchor, size, scope and how it was set, nor about the specifics of the seabed. As I understand it that particular location has very poor holding and that the "draggers" may be lulled into a false sense of security when anchoring in settled conditions and not being properly prepared for the increase in wind. The fact that others like you do not drag suggests it is not inevitable and there are strategies for avoiding it.

I saw similar things in the 10 years I kept my boat in Greece. Usual causes are poor design of anchors used and poor setting technique. Going up a size does not change this, whereas changing to a more suitable anchor and knowing how to set it does. See Vyv Coxs earlier posts on his experience of changing to a Rocna.

Again if you read the whole thread you will find there is a lot of middle ground. The extremes arise when a stand is taken but not supported by any evidence, or the evidence offered does not show what it is claimed to show. The problem with supporting a case with "tried and tested over the years" does not mean that an alternative could not just as easily pass the same test. It is easy to show that weight/size on its own is not a determinant of performance, whether it be hold or setting ability and it is not unreasonable to accept that better designed, lighter weight equipment can produce better outcomes. Indeed there are plenty of empirical tests that show exactly that. If your crusty cruisers think they are being told they are doing it all wrong, that maybe shows that they are not hearing the arguments properly - that is there are proven alternatives that are equally as good or better. Such is the way of the world in all areas of human endeavour and there are always people who prefer not to recognise it.

BTW don't think anybody has suggested a connection between engine size and anchor choice. Engine size/power has only been used as a medium for evidencing the load that can be placed on an anchor and compare with loads placed on the boat at different wind strengths. Useful for understanding the hold potential from power setting the anchor.

 

[geem]

Who told you that? Happens all the time. Getting near August when Europe takes a month off & it's drag racing time. Experienced cruisers will be anchored up wind. In Culatra pretty much every day when the wind goes up to about 25kts every afternoon there will be boats dragging. Maybe not in your neck of the woods where most run back to the mooring or marine if the forecast gets up. Textbook conformation bias.
Lets face it, these threads are storm in a teacup, people don't generally upsize. Apart from long term full time cruisers who very often will. With no real downside, just year in year out uncertainty, can`t trust the weather, the bottom, being able to get as much scope as you like. Bit bigger puts the odds a bit more in favour of you home staying where you want it to be. It's like god of the gaps, point out an argument doesn't hold up in the real world & someone will run around to find another one. You don't size a hook by engine size, bit of slack & get a load of way on in reverse. Been a common practice by many for years. It works.
And few sailors pay too much attention to rants on the web anyway, forums & are generally viewed somewhere between hilarity & incredulity. crusty cruisers with heavy duty anchoring systems tried & tested over the years having a sundown in some shack on a beach somewhere would fall on the floor laughing at some journo ranting page after page telling them they were doing it all wrong.
Pity really, absolutely no point on posting a thread even mentioning anchor now, it gets derailed straight away into opinionated rants with no chance of seeing any middle ground.

I know that area pretty well. A few years back, the eastern end of the anchorage had better holding than near the village. This was because it was clear of sea grass. For whatever reason the seagrass is now in the eastern end of the anchorage and there is less seagrass by the village. We were in the Eastern anchorage a couple of years ago because we prefer it there. The wind was blowung about 20kts. We were anchored on our Spade anchor. 3 boats with delta anchors were nearby. The wind started to gust to about 25kts and one of the boats started to drag. 5 mins later the next one started to drag. A local Portuguese guy who also had a delta anchor, went over to tell both boats that they must put out at least 5:1 with there delta anchors before they load them up. They both did this and didnt drag again. Delta a chorus seem to really struggle with seagrass both at Culatra and here in the Caribbean. They are still widely used by charter boats but they really are not suitable for grass seabeds in my experience. They are the number one dragging anchor in the Caribbean based on what we see

 

[GHA]

I dragged!!
Red before, magenta now.

Now that is interesting. No real wind from that direction don't think. LAT/LONG/wind/heading/sog/cog all in a database. Might take a few days with an AI to get the data into some sort of useful format.
If anyone wants an objective chat about digging into the data & see if anything useful can be found it's blatantly oblivious here is not the place. I've a random discord channel, Join the Raspberry Pi boat monitoring Discord Server!
Good a place as any imho, public forums just end up in a conformation bias fuelled bun fight.

 

[thinwater]

... BTW don't think anybody has suggested a connection between engine size and anchor choice. Engine size/power has only been used as a medium for evidencing the load that can be placed on an anchor and compare with loads placed on the boat at different wind strengths. Useful for understanding the hold potential from power setting the anchor.

Interesting question.

My cruising cat had about 500 pounds thrust in reverse (twin high thrust outboards), enough for a good power set. My trimaran (F-24) has a 4hp, the exhaust comes through the prop, and has only about 50 pounds of reverse thrust. It can't power set an anchor that is even several sizes under. You can increase that by gathering some slack and backing down hard a few times. I don't anchor out with that boat too often. Generally only for the afternoon in a couple of good sand swimming and kayaking locations with firm, fine sand. It can just barely set a 2.5-pound Gaurdian. I mosly use an alloy Excel #1 (8 pounds) or a 13-pound Northill. I know if I had the recomended 15- to 20-pound anchor (high windage trimaran) it would not be set.

Of course, this is rarely the case with a cruising boat. But some boats are seriously underpowered for power setting and rely mostly on the rising wind.

With a windlass and a good engine, the standard size is great. Up a size is OK. There is no sense in having a smaller fair weather anchor. But with little power and no windlass, a smaller anchor has a number of advantages, IF the sailor knows how to take full advantage of what a good anchor can do. I rely on good technique and rigging.