Deliberately starting an anchor thread.

[JumbleDuck]

Look at their tables. A step up corresponds with nearly double the displacement weight. I am not part of a conspiracy to deceive.

Anchoring loads are only tenuously connected to displacement.

 

[JumbleDuck]

I have said, many times, they require skill and patience to set - and some obviously had, or developed that skill.

I have never had any problems getting mine to set, but I bought a slightly bigger one than I had because I think it probably digs in a bit faster. I don't do any of the thrashing around in reverse business, because I think that gentle loading, at least initially, does the job better.

That said, I have only once anchored in haste, when my engine failed outside the marina entrance in wild gusting (F8+) weather. The smaller CQR I had then set instantly and held rock solid until a workboat came out to get me. Thank goodness.

 

[JumbleDuck]

I'm talking about double displacement, not anchor, though it is nearly double too. Round figures, note. Please let's not quibble.

However, going up one size in anchor is normally only about 20% in anchor weight (feel free to insert the relevant figures) for your anchor, which means, if you're lucky, at most 20% extra holding power. It's interesting that most manufacturers reckon that extra 20% to be good for 100% for displacement ...

 

[JumbleDuck]

JRM needs men like you in his office. Apply for a job.

That's a bright idea. As bright as a 341BTU/hour light bulb!

 

[mainsail1]

If anyone wants my 45lb CQR for free they can have it.........That's my view of CQR anchors.

Seriously, it is sitting in the shed and will never be used again by me.

 

[Kukri]

Where is it?

 

[Sybarite]

Nobody but a fool would risk losing his boat and possibly his and other's lives by using an unsafe anchor.

The CQR anchor was patented in the 1930s.

The great number of them still being used demonstrates that it It has been a very successful anchor.

If it had not been, you would not see so many of them in use around the world, since there are many readily available and competitively priced alternatives on the market.

It may well be that better anchors have been invented since the CQR first came on the market more than 80 years ago.

That does not mean that the CQR has suddenly become useless, anymore than the emergence of a new mobile phone immediately renders its predecessors useless.

The CQR was Eric Hiscock's choice of anchor.

If it was good enough for him, it's good enough for me.

I chose CQR anchors for the three boats I have owned.

I have never had any reason to regret doing so.

The CQR :

Some observations from French tests (paraphrased)

The overall results were so poor in relation to the other anchors that we did not bother including it in the summary.

If the boat swings the anchor often falls on its side and the weight of the hinge prevents it from resetting.

Worst performance ; highest price.

My presonal choice wold be Spade which consistently comes out top in comparative boat tests. It's a bit more expensive but what is a couple of hundred quid compared with the value of your boat?

 

[Neeves]

:encouragement:

Cruise long enough and I suspect a lot of people will eventually take onboard that your capacity to predict the future or have any significant control over a lot of the day to day future can be limited. So shoving the odds a bit more in your favour when it all goes a bit crazy in the anchorage is very much a *good thing* !! If buying a new anchor then going a bit bigger just seems so obvious with no downside other than a few quid.

Strange that a few get so annoyed about this.......

You forget - one of the major proponents of the big anchor philosophy is actually using a 68kg anchor where for that size of vessel Rocna suggest 33kg (the next size up Rocna would be 40kg).

So a, decent, 15kg anchor produces a hold of 2,000kg in decent sand - so on Noelex calculation his anchor will produce well in excess of 8,000kg of hold. He shows a lot of confidence in his anchor - its never be tested at all (which seems a bit of a contradiction - using an untested anchor and suggesting he knows what he is doing???). I love to know how that will develop (and whether the rest of the kit being used has been upsized accordingly - as it, chain, shackle, chain lock etc should have been chosen with the same (or similar) safety factors in mind. It would be interesting to know what safety factors were used 2:1, 4:1.

Where exactly do you stop when upsizing - and why.

You, GHA, also have not quite explained, if at all, why when you decided to upsize your 'almost flawless' Rocna you swapped to a Spade. You never mentioned what the flawed part of the Rocna was that prompted the change (it must have been significant to invest in an expensive Spade) - was it really just weight (and if so - how did you know). I'm not quite sure how (or why) you attribute the better safety you apparently have to the extra weight and not the different design. If it was simply the weight issue why not replace the small Rocna and not a bigger one. Maybe this is your idea of a 'technical investigation'. Excuse me if I'm a bit mystified and wonder how you can disparagingly reject some conclusions when your conclusions themselves lack any basis - for the reader to peruse.

Like Noelex - I expect you to dodge the questions.

Jonathan

 

[Neeves]

I’m learning some nautical terms here like a Thames ton, which I was able to look up, but what does a cat weigh?

As Zoidberg recalls, almost, correctly 7t. Thats cruising weight, 400kg of water 200kg of fuel, food, 2 crew and the extra kit we carry Liferaft (for one). Dry weight is 6t. 38' x 22'6" beam 2 x 20hp engines (and the windage of a 45' Bav). And we draw 1m (mini keels)

Also as Zoidberg recalls we use 6mm chain and alloy anchors (8kgs each, 4 in total) - but equiv to 15kg steel models - saving a bit there and we would try not to actually have all that water - we have a desal unit. And picking up on a point Minn made - our chain is stored just forward of the mast (along with the windlass and 'extra' anchors)The batterie bank is just behind the mast, centralising weight and ensuring a short cable run to the windlass) the bower is on a bow roller about 2m aft of the bows and yes we use 30m snubbers) another nice mix of metric and imperial (weights are metric).

Blame boat builders for 'imperial' why - even the French define many, most of their yachts with imperial length measurements. And marine diesels are also designated with HP - bizarre.

Jonathan

 

[JumbleDuck]

Blame boat builders for 'imperial' why - even the French define many, most of their yachts with imperial length measurements. And marine diesels are also designated with HP - bizarre.

I think it's because there is a natural human tendency to prefer bigger numbers: there are more feet than metres and more HP than kW.

 

[Neeves]

I think it's because there is a natural human tendency TO PREFER BIGGER numbers: there are more feet than metres and more HP than kW.

You mean like anchors?.......

 

[LittleSister]

I’m learning some nautical terms here like a Thames ton, which I was able to look up, but what does a cat weigh?

As Zoidberg recalls, almost, correctly 7t. Thats cruising weight, 400kg of water 200kg of fuel, food, 2 crew and the extra kit we carry Liferaft (for one). Dry weight is 6t. 38' x 22'6" beam 2 x 20hp engines (and the windage of a 45' Bav).

Thames tonnage is nothing to do with the weight/displacement of the vessel! It's a notional cargo carrying capacity of the vessel, calculated using length and breadth.
https://en.wikipedia.org/wiki/Thames_Measurement
See also the following re its origins/rationale:
https://en.wikipedia.org/wiki/Builder's_Old_Measurement

p.s. - For example, my boat displaces about 4 tons, but its Thames Tonnage is about 8, I think.

 

[noelex]

There have been repeated calls, over many anchoring threads, to “prove” that a larger anchor can be used at a shorter scope than a smaller anchor. These are such pointless arguments that I usually ignore them, but having started down this path it is worth settling this issue.

In this thread everyone is agreed that, if all other factors are constant, a larger anchor of the same design and material will have a higher maximum holding power than a smaller anchor (ignoring atypical substrates such as rock). This seems to have been conceded (really it is very silly to argue otherwise), with only the amount of gain in question. Even here the most pessimistic suggestion offered is that the coefficient is between 0.83 and 0.7 (in other words doubling the anchor weight increases the holding of an anchor between 83% and 70%). So everyone seems agreed that increasing anchor size produces a substantial gain in the maximum holding power.

The next element is for everyone to agree that a longer scope will provide a higher maximum holding power than a shorter scope, (once again there will be rare exceptions, and the amount of gain beyond around 10:1 becomes very small). I am happy to “prove” longer scopes will produce higher maximium holding powers if required, but I dont think this should be necessary.

It therefore follows as matter of common sense (or deductive logic if you prefer) that if anchored at for example 5:1 with a small anchor that increasing the size of the anchor, while leaving all other variables unchanged, will enable the scope to be reduced for example to 4:1 with the same holding power. This is just one example, where the logic is undeniable.

I think conversely is can be deduced that anyone who uses a very small primary anchor (such as an A80 Spade rated for catamaran shorter than 25 feet and 2T, on a 38 foot 7T catamaran ) will need to use a longer scope (or other tactics such as using multiple anchors) than would be normally be required in the same conditions (substrate wind strength etc). This explains why the owner will never anchor at less than 5:1. This is entirely sensible and necessary with this choice of anchor size.

I think after the repeated calls to “prove” that a larger anchor can be used on shorter scope it is incumbent on someone who advocates small anchors to “prove” why they do not need to used at a longer scope to maintain the same levels of safety if they disagree with above.

Apologies for the long post labouring on what should be obvious points, but hopefully by settling this issue we can avoid the frequent sidetracking of anchor threads in the future. I hope we can consider the statment that a larger anchor can be used at shorter scope than otherwise identical smaller anchor is “proved”.

Ever the optimist here.

 

[Neeves]

It therefore follows as matter of common sense (or deductive logic if you prefer) that if anchored at for example 5:1 with a small anchor that increasing the size of the anchor, while leaving all other variables unchanged, will enable the scope to be reduced for example to 4:1 with the same holding power. This is just one example, where the logic is undeniable.

.

I am obviously very, very stupid.

If we have the magic ability to replace the small anchor with a large anchor, same yacht, same seabed, same anchor design - then the small anchor will have had the same hold as the bigger anchor that suddenly replaces it,

If the windage of the yacht, or its engine capacity, was able to set the small anchor to 400kg holding capacity then the bigger anchor will also have a hold of 400kg.

So run me through why the big anchor will be more reliable than the smaller one (if the scope is reduced). Both have the same hold - the only difference is one is bigger (and both actually have a huge reserve of hold (the bigger one might have a reserve of 2,600kg the smaller one a reserve of 1,600kg).

Jonathan

 

[mainsail1]

Where is it?

Newbury, Berkshire.

 

[Munz]

I am obviously very, very stupid.

If we have the magic ability to replace the small anchor with a large anchor, same yacht, same seabed, same anchor design - then the small anchor will have had the same hold as the bigger anchor that suddenly replaces it,

If the windage of the yacht, or its engine capacity, was able to set the small anchor to 400kg holding capacity then the bigger anchor will also have a hold of 400kg.

So run me through why the big anchor will be more reliable than the smaller one (if the scope is reduced). Both have the same hold - the only difference is one is bigger (and both actually have a huge reserve of hold (the bigger one might have a reserve of 2,600kg the smaller one a reserve of 1,600kg).

Jonathan

I'm a little confused,

As you've pointed out, under optimal conditions both anchors have an abundance of reserve holding capacity (2600 kg and 1600 kg), so in the vast majority of situations the small anchor is perfectly adequate.
But in the case of a substrate that is less than ideal (for example thin soupy, mud in the estuary I find myself in now), the reserve holding capacity is maybe going to be reduced (say by 50% to 1300kg and 800kg respectively.

Again with adequate scope, these are both well in excess of the 400 kg required in your example, so any prudent sailor would still be fine with the smaller anchor.

Those reserve capacity's assume a scope of around 10:1, and the holding power is commonly assumed to drop off as scope gets shorter, unfortunately there is no information on how they got the numbers, but the chart here: https://cruisingodyssey.com/2017/09/18/see-this-chart-to-find-the-chances-of-your-anchor-holding/ suggests reducing the scope to 2:1 will reduce the holding "power" to 35% of that available at 10:1 scope.

Actually I suspect the drop-off may be more dramatic than the chart suggests and probably depends to some extent on both the anchor design and the substrate.

But anyway going back to the example, if some idiot like me was to rock up and try to anchor on a 2:1 scope, maybe because it's deep, the anchorage is crowded or I've foolishly been paying too much to GHA and/or Nolex's advice, then the large anchor would still have 455kg of reserve capacity (2600*0.5*0.35), which is still above to 400kg needed, but the smaller one may only have 280kg of reserve capacity (1600*0.5*0.35)?

So where am I going wrong?

 

[Neeves]

The difference in the angle of scope at 5:1 and 10:1 is not going to develop material differences in the hold developed, remembering both anchor are being tensioned with the same scopes.

The example I quote needs anchors of say 20kg and 35kg (more like Noelex' practice) not the one size up that might be 20kg and 25kg.

You have reserve capacity - but in order to make that capacity available we need stronger wind or a bigger engine.

We have reduced the scope to 2:1, your example, have you, or anyone else, any idea how much extra capacity you will develop vs wind necessary to do so, with either anchor with a scope of 2:1?

At a scope of 2:1 - the yacht will veer and hobby horse, violently (in any wind) and all movement of the yacht will reduce hold further because the chain will impact directly on the seabed, liquifying the seabed in immediate proximity to the anchor - and hold for both anchor will diminish - perfect dragging conditions - the wind impacted the yacht - it windage allowed a tension of 400kg (in both anchors) now that hold has reduced to, say, 300kg - throw in yawing, hobby horsing

I hope you never are forced to anchor at 2:1.

I'm not optimitistic.

But if you had 2 anchor deployed - both could be 'set' at 400kg they could be set to match the limit of yaw - so both are taking tension in the set direction. I still don't fancy your chances - but I think they are now a little better.

Jonathan

One reason I have a problem with the big anchor at short scope is:

Both anchors are set to the same holding capacity.

One has a longer lever arm acting on it - why does it not pop itself out more quickly than the one with the shorter arm. With a 20% difference in weight the difference in shank length is not much - but its still there. if we double anchor size the difference is noticeable.

close edit

 

[Zing]

However, going up one size in anchor is normally only about 20% in anchor weight (feel free to insert the relevant figures) for your anchor, which means, if you're lucky, at most 20% extra holding power. It's interesting that most manufacturers reckon that extra 20% to be good for 100% for displacement ...

Not at the heavier end of the range, which is what I am looking at. Anyway the displacement and size are closely related as can be seen from manufacturers tables, which is my point, so I don’t see your point. I did ask you to please not quibble.

 

[JumbleDuck]

Not at the heavier end of the range, which is what I am looking at. Anyway the displacement and size are closely related as can be seen from manufacturers tables, which is my point, so I don’t see your point.

I'll try again. Yes, manufacturers link displacement and size, but it's not a linear relationship. They normally recommend a 20% increase in size for a 100% increase in displacement.

 

[capnsensible]

Simple question.

Does your anchor hold when its windy.

1. No. Get bigger anchor.

2. Yes. No further action required.