Advice on ground tackle

[Dockhead]

Originally Posted by Izikalvo

"anchors increase holding capacity over time"
Indeed, no matter what size they are, a well-buried anchor performs better than a half-buried anchor.

I define 2 mechanisms that negate the idea that a large anchor is better than a small one. Larger anchors are more prone to tripping in a change of wind/tide and large anchors do not resist yawing as well as smaller anchors.
As the wind increases it is the windage of the yacht that determines the tension and that tension will be the same for a large or small anchor (for the same yacht). If the tension increases beyond the ultimate hold of too small of anchor then it will drag. However, as long as the anchor is not ridiculously small you will never exceed the hold of a sensibly sized small anchor (the size the manufacturer recommends). A 15kg efficient anchor, Spade, Viking (add whatever anchors you want) will develop hold in a clean sand seabed of about 2,000kg (Viking, even more). You will never experience a 2t tension in your rode - an 8mm G30 chain will begin to stretch at about 1,500kg. An anchor larger than the anchor maker's recommendation will have a higher ultimate hold - but your wife will sue for divorce long before you drag the small anchor and stretch the chain. Measurement suggests that at 35 knots the tension in the rode for a 45 Ft production yacht, actually, a Bavaria, will be about 650kg - a long long way from the ultimate hold of a good modern 15kg anchor of 2,000kg. It is unlikely many people will be anchored subject to the full fury of 35 knots (but possible). There is simply no need to increase the size of your anchor beyond the manufacturer's recommendation - and if you do go large possible self-inflicted harm might occur.

"It is unlikely many people will be anchored subject to the full fury of 35 knots (but possible)" What?! Where do you get this? I was just two days ago subject to 40+ knots of wind overnight at anchor. I've been through nights at anchor in hurricane force winds, and this is not an exceptional experience for long-term cruisers.

And why would larger anchors be "more prone to tripping in a change of wind/tide and large anchors do not resist yawing as well as smaller anchors." This is utter nonsense.

The very article you cited says why. The bigger the anchor, the less it will move around in the seabed, and the better the soil will retain its integrity and therefore holding.

Every cruiser with a modicum of experience knows that bigger is better, and disproportionately so. When people start to laugh at the size of the anchor in your roller, is when you know you are approaching the optimum size. I think it was Dashew who said that, and no one knows more about anchoring.


The manufacturers' recommendations are only good up to a certain wind force and in optimal holding -- will that be enough? If you are a weekend sailor who anchors rarely, and is never far from a safe harbour, then sure. But that is not the use case of many of us. The rest of us need to be ready for dealing with strong conditions and less than optimal holding. To be sure that you can manage in that, you really want the biggest anchor you can carry.

[GordMay]

Originally Posted by Dockhead

... Every cruiser with a modicum of experience knows that bigger is better, and disproportionately so. When people start to laugh at the size of the anchor in your roller, is when you know you are approaching the optimum size.
... you really want the biggest anchor you can carry.

Well said!

And, that goes for your deck hardware, as well.
You really want the biggest anchor you can carry, and handle.

[smj]

Originally Posted by GordMay

Well said!

And, that goes for your deck hardware, as well.
You really want the biggest anchor you can carry, and handle.

So I can manhandle a 66lb. anchor with all chain rode in a pinch, but do I want that on my 22’ racing monohull that I’ve converted into a cruiser?
What if a 35lb. Mantus has better holding power than a 65lb. CQR? Would I want the CQR over the Mantus?
Me thinks it takes more common sense than that?

[Izikalvo]

I will leave it here, too much talking on a subject already proven, not by armchairs gurus, by facts, use any anchor you wish, my advice, use the anchor size suggested by the manufacturer, we have data collected from many users and from many tests, fair winds and anchor safely.

https://www.vikinganchors.com/data-c...-always-better

[Dockhead]

Originally Posted by Izikalvo

I will leave it here, too much talking on a subject already proven, not by armchairs gurus, by facts, use any anchor you wish, my advice, use the anchor size suggested by the manufacturer, we have data collected from many users and from many tests, fair winds and anchor safely.

https://www.vikinganchors.com/data-c...-always-better

"Armchair gurus"? Are you serious? There are probably a few hundred years of cumulative anchoring experience posting in this thread.


And again, I have to correct this "use the size suggested by the manufacturer". Even the manufacturer doesn't say this. The clever ones suggest different sizes for different conditions, like this one: https://www.mantusmarine.com/mantus-...anchor-sizing/ For long distance cruisers who may be far from any harbour and may encounter any weather, the anchor should be capable of holding in storm conditions and in a poor holding bottom.


Because holding power for a given anchor goes down steeply with quality of the bottom (see Alain Fraisse's excellent work on this), something which is not taken into account in the Viking article linked, which treats holding power of a given anchor as a constant, you can never have an anchor which will hold in all conditions and all bottoms and at all scopes. That is why you get as close as you can by using as big an anchor as your can physically handle.


The Viking article states that a too big anchor is actually "dangerous" (!) because it won't set as well as a smaller one. This is pernicious nonsense. Any boat capable of motoring in reverse, with a decent size motor and decent size prop, can fully set an anchor several times larger than what that boat could carry. Larger anchors are easier, not harder to set, because of soil mechanics, first of all, and secondly, larger anchors of the same time are heavier compared to their fluke area, so denser, bringing more pressure per unit of area on the flukes, so penetrate better. Alain Fraisse has published some good work on this.

Originally Posted by smj

So I can manhandle a 66lb. anchor with all chain rode in a pinch, but do I want that on my 22’ racing monohull that I’ve converted into a cruiser?
What if a 35lb. Mantus has better holding power than a 65lb. CQR? Would I want the CQR over the Mantus?
Me thinks it takes more common sense than that?

First of all, anchoring a 22' racing mono is, obviously, a completely different job from anchoring a long-distance cruising boat, which requires different gear. Do you ever even anchor overnight? I'd use a Fortress on rope rode, I think.


Second, of course you prefer a 35lb Mantus over any size CQR. Read all the above with the words "of a given type".

[smj]

Originally Posted by Dockhead

"Armchair gurus"? Are you serious? There are probably a few hundred years of cumulative anchoring experience posting in this thread.


And again, I have to correct this "use the size suggested by the manufacturer". Even the manufacturer doesn't say this. The clever ones suggest different sizes for different conditions, like this one: https://www.mantusmarine.com/mantus-...anchor-sizing/ For long distance cruisers who may be far from any harbour and may encounter any weather, the anchor should be capable of holding in storm conditions and in a poor holding bottom.


Because holding power for a given anchor goes down steeply with quality of the bottom (see Alain Fraisse's excellent work on this), something which is not taken into account in the Viking article linked, which treats holding power of a given anchor as a constant, you can never have an anchor which will hold in all conditions and all bottoms and at all scopes. That is why you get as close as you can by using as big an anchor as your can physically handle.


The Viking article states that a too big anchor is actually "dangerous" (!) because it won't set as well as a smaller one. This is pernicious nonsense. Any boat capable of motoring in reverse, with a decent size motor and decent size prop, can fully set an anchor several times larger than what that boat could carry. Larger anchors are easier, not harder to set, because of soil mechanics, first of all, and secondly, larger anchors of the same time are heavier compared to their fluke area, so denser, bringing more pressure per unit of area on the flukes, so penetrate better. Alain Fraisse has published some good work on this.





First of all, anchoring a 22' racing mono is, obviously, a completely different job from anchoring a long-distance cruising boat, which requires different gear. Do you ever even anchor overnight? I'd use a Fortress on rope rode, I think.


Second, of course you prefer a 35lb Mantus over any size CQR. Read all the above with the words "of a given type".

A quote from Jedi:
“But the weather will set the anchor further. I can’t set our 176lb Bruce in a hard bottom, but after a squall has passed it is fully buried.”
So it seems his anchor is to large for his boat/motor? This is what got me started on this thread. When I anchor I want to know my anchor is set and not have to hope a squall comes by to set it for me.
And from the Spade anchors website:
“The Manufacturer of the SPADE anchor never refers to an anchor's weight, but rather to its effective surface area. The remarkable efficiency of a SPADE anchor is due to the size and shape of its effective surface: SPADE anchors of the same surface area will have the same holding power, no matter the material of which they are made.”
You seem to like your Spade anchor yet they state it’s not the weight that gives the Spade anchor it’s holding power but rather the design and surface area, something I believe to be much more important, the design.

[smj]

[QUOTE=smj;3654410]A quote from Jedi:
“But the weather will set the anchor further. I can’t set our 176lb Bruce in a hard bottom, but after a squall has passed it is fully buried.”
So it seems his anchor is to large for his boat/motor? This is what got me started on this thread. When I anchor I want to know my anchor is set and not have to hope a squall comes by to set it for me.
And from the Spade anchors website:
“The Manufacturer of the SPADE anchor never refers to an anchor's weight, but rather to its effective surface area. The remarkable efficiency of a SPADE anchor is due to the size and shape of its effective surface: SPADE anchors of the same surface area will have the same holding power, no matter the material of which they are made.”
You seem to like your Spade anchor yet they state it’s not the weight that gives the Spade anchor it’s holding power but rather the design and surface area, something I believe to be much more important, the design.[/

[Dockhead]

Originally Posted by smj

A quote from Jedi:
“But the weather will set the anchor further. I can’t set our 176lb Bruce in a hard bottom, but after a squall has passed it is fully buried.”
So it seems his anchor is to large for his boat/motor? This is what got me started on this thread. When I anchor I want to know my anchor is set and not have to hope a squall comes by to set it for me.
And from the Spade anchors website:
“The Manufacturer of the SPADE anchor never refers to an anchor's weight, but rather to its effective surface area. The remarkable efficiency of a SPADE anchor is due to the size and shape of its effective surface: SPADE anchors of the same surface area will have the same holding power, no matter the material of which they are made.”
You seem to like your Spade anchor yet they state it’s not the weight that gives the Spade anchor it’s holding power but rather the design and surface area, something I believe to be much more important, the design.

Setting behavior and holding power are two different things, and both are important.

You are right that all other things being equal, holding power is proportionate to fluke area, not weight. That's been proven by research. And of course design. No one said anything different

But getting the anchor set - and keeping it set - is related to weight, and weight/fluke area to get penetrating pressure. Some anchors (Fortress) work well in many bottom types without weight. But why does none of us use a Fortress as best bower? Because without weight it won't set in every bottom type and, notoriously, often won't reset.

As to Jedi's case - he can speak for himself, but I'll wager that with that giant anchor he simply doesn't bother doing a full power set. It simply sets itself - the beauty of a giant anchor. I had a 121 pound Rocna, and I did not indeed just let it set itself, but a fully buried power set was no problem The idea that you should use a tiny anchor (Viking recommend 21kg or something for my boat) because anything bigger is "dangerously" hard to set, is simply ludicrous.

[Izikalvo]

Originally Posted by Dockhead

Setting behavior and holding power are two different things, and both are important.

You are right that all other things being equal, holding power is proportionate to fluke area, not weight. That's been proven by research. And of course design. No one said anything different

But getting the anchor set - and keeping it set - is related to weight, and weight/fluke area to get penetrating pressure. Some anchors (Fortress) work well in many bottom types without weight. But why does none of us use a Fortress as best bower? Because without weight it won't set in every bottom type and, notoriously, often won't reset.

As to Jedi's case - he can speak for himself, but I'll wager that with that giant anchor he simply doesn't bother doing a full power set. It simply sets itself - the beauty of a giant anchor. I had a 121 pound Rocna, and I did not indeed just let it set itself, but a fully buried power set was no problem The idea that you should use a tiny anchor (Viking recommend 21kg or something for my boat) because anything bigger is "dangerously" hard to set, is simply ludicrous.

bigger doesn't have to be heavier and heavier doesn't have to be bigger, this sentence belongs to the past, compare the fluke area for a start.

[CaptainRivet]

Originally Posted by Dockhead

"It is unlikely many people will be anchored subject to the full fury of 35 knots (but possible)" What?! Where do you get this? I was just two days ago subject to 40+ knots of wind overnight at anchor. I've been through nights at anchor in hurricane force winds, and this is not an exceptional experience for long-term cruisers.

And why would larger anchors be "more prone to tripping in a change of wind/tide and large anchors do not resist yawing as well as smaller anchors." This is utter nonsense.

The very article you cited says why. The bigger the anchor, the less it will move around in the seabed, and the better the soil will retain its integrity and therefore holding.

Every cruiser with a modicum of experience knows that bigger is better, and disproportionately so. When people start to laugh at the size of the anchor in your roller, is when you know you are approaching the optimum size. I think it was Dashew who said that, and no one knows more about anchoring.


The manufacturers' recommendations are only good up to a certain wind force and in optimal holding -- will that be enough? If you are a weekend sailor who anchors rarely, and is never far from a safe harbour, then sure. But that is not the use case of many of us. The rest of us need to be ready for dealing with strong conditions and less than optimal holding. To be sure that you can manage in that, you really want the biggest anchor you can carry.

And that would mean get the biggest viking you can fit, because it has the highest holding power per kg weight and to help setting you get the biggest that fits?
But why Viking advising you to take the smaller anchor. They cost more and Viking would earn more which is the purpose of a company?

I think that most blue water cruisers that have trouble with the anker and weight/size don't realize how heavy thier boat really is with all the cruising kitty and provisions plus the much higher windage due to fully enclosed Biminis, solar arches which big surfaces of solar panels and davits with dingys.
Just had a 40ft next to me on the dry dock which placing the waterline 15cm deeper, suggest him to ask about the total weight when hauling and recalculate if his anchor still fits the specs... Well it didn't, he needs to go one size up but will go 2 right away. Chain is on the limit too..

[rslifkin]

Originally Posted by Izikalvo

bigger doesn't have to be heavier and heavier doesn't have to be bigger, this sentence belongs to the past, compare the fluke area for a start.

Fluke area is important. But within a given design of anchor, fluke area and weight are related. And weight does help with getting a good set in a crappy bottom with weeds, etc. as it'll push through the junk better to allow the tip of the anchor to actually dig in instead of just getting dragged along through the junk without biting.

[s/v Jedi]

Okay, let me try to explain this: I never meant to say that I can’t set my anchor in hard sand; I can’t-fully- set it unless maybe running my engine at full throttle in reverse, which kicks up my stern with the prop cavitating etc. which I simply refuse to try because there is no need.

So my anchor is partially set with the anchor on it’s side and one fluke still sticking up above the seabed. All that you need to do to achieve a full set is pull harder. Up to 40kts of wind the anchor won’t set much more, because this partial set has more holding power than what 40kts of wind can pull at it.

This is how I anchored the boat when hurricane Isaias approached 2 years ago and after it had passed, the anchor was perfectly set with just the shackle showing.

Now for the catch: with one fluke sticking up, when you circle around the anchor with switching wind directions, the chain can wrap around it, increasing the chances of the anchor upturning when a squall hits. I had this happen a year ago and that was the first time since 2002 when we bought Jedi, so it’s rare. We now eliminate this risk by re-anchoring after turning circles, cleaning grass off the anchor etc.

Also: this is all about hard sand bottoms only. Most anchors under 66lb will not set in this at all, they just scrape along the bottom.

[Dockhead]

Originally Posted by Izikalvo

bigger doesn't have to be heavier and heavier doesn't have to be bigger, this sentence belongs to the past, compare the fluke area for a start.

You missed the point. Fluke area and weight have different functions in anchor performance. More fluke area will give greater maximum holding power. But more weight gives more pressure per unit of area and so more penetrating power. Weight affects setting behavior, especially in difficult bottoms, and affects resetting behavior. It's important.



It is possible to make an anchor which works under some circumstances without much weight -- Fortress is the bright example. Fortress works with a lot of fluke area, good geometry, and very sharp flukes. But without weight, Fortress doesn't work in all bottoms and doesn't reset well after a wind shift. That's why probably zero point zero percent of long term cruisers use Fortress as our main bower anchor (although most of us have a Fortress for a kedge).

[Dockhead]

Originally Posted by rslifkin

Fluke area is important. But within a given design of anchor, fluke area and weight are related. And weight does help with getting a good set in a crappy bottom with weeds, etc. as it'll push through the junk better to allow the tip of the anchor to actually dig in instead of just getting dragged along through the junk without biting.

Indeed. And helps keep the anchor set, and helps the anchor reset in case of a wind shift.

[Izikalvo]

Originally Posted by Dockhead

You missed the point. Fluke area and weight have different functions in anchor performance. More fluke area will give greater maximum holding power. But more weight gives more pressure per unit of area and so more penetrating power. Weight affects setting behavior, especially in difficult bottoms, and affects resetting behavior. It's important.



It is possible to make an anchor which works under some circumstances without much weight -- Fortress is the bright example. Fortress works with a lot of fluke area, good geometry, and very sharp flukes. But without weight, Fortress doesn't work in all bottoms and doesn't reset well after a wind shift. That's why probably zero point zero percent of long term cruisers use Fortress as our main bower anchor (although most of us have a Fortress for a kedge).

Setting a new design anchor is done by wind and/or engine power, with nothing to do with weight, Leave a heavy anchor and a light anchor on the seabed and when you come back the next day they will both be sitting on the seabed.
Take, say, the Spade or Sarca excel, they both make aluminum and steel versions, do they set differently? Mantus seabed penetrating performance is excellent, that is because of its design, Mantus has a very sharp fluke/shackle hole angle which makes the anchor very good in penetrating the seabed, however, this angle compromises its holding, it has been already proven by many researchers that the best holding angle of fluke to the seabed is about 30 degrees, and in soft mud 40, no argue on that I hope,
Take Mantus and Viking of the same size, same area, both will set great, indeed Mantus is heavier but it sets because of its sharp fluke/seabed angle, not its weight, and because of that does not produce the same hold as the Viking, in fact, the hold is about 50% of the Viking, why? - one reason is design, the other reason is the steel, Viking uses thinner and therefore lighter HT steel that produces less resistance when setting, kind of a razor blade.

There are documents made by MIT and the US navy researches to support the best holding angles in the seabed, please trust me on that.

Nothing against Mantus, it's a great anchor but has its flaws, same as the rest of us.