An Anchor Thread! Grab your beers and popcorn.

[NormanS]

Norman - you have said this before

But you bent link is identical to one made by Oscalutti and another I have seen of unknown origin.

Was yours original?

I don't understand your complaints. You know what I am saying yet you seem to read every new post I make. You object to the idea that people new to the forum might benefit from my posts. You read my posts voluntarily - and then complain.

Jonathan

You misunderstand. I'm not complaining about your posts. Post as much as you like.
What I do find a bit wearing, is your constant and repetitive advice to all and sundry, that they would be better off with lighter chain, and a cat's cradle of elastic, instead of the perfectly good equipment that they already have. You don't know these people, or their capabilities. You don't know their boats, or the areas in which they sail. There is just a possibility that they might know better.

 

[RunAgroundHard]

... I'm firmly in the Norman S camp ... I always use a snubber now, but it's only 3 meters long. Considering a much longer one now.

I think you are camping in a different country than NormanS's camp site.

 

[geem]

I'm not going to try to compete on word count, Jonathan. ?
It's worth pointing out to anyone who actually reads your essays, that your boat is very much at the extreme lightweight end of the spectrum. As I wrote earlier, having substantial chain is an option not available to you, and as a result of using "lavvy" chain, you are obliged to rig complicated stretchy snubbers. That's fine, but why try to convert everyone else to your unnecessary complications?
It is unfortunate that the term "snubber" is used for the normal everyday device for taking the chain load off the windlass, (surely everyone does that), but is also used for the macramé of pensioned off climbing rope, favoured by yourself.
I favour an all chain rode of a substantial size. At present we have 65m of 10mm chain on a chunky 11m boat. It works well for us, but far be it from me to tell others what they should do.

Our 13.4m 19 tonne boat benefits from a 12 metre long snubber. We wouldn't anchor without one. We have 60m of 10mm chain and an additional 50m of anchorplait. I can confirm that the conditions we anchor in the snubber is a valuable addition to our anchoring system. As I look around the anchorage we are currently in I would estimate the number of boats that don't have snubber fitted it less than 10% of boats

 

[geem]

Monday night here in Curacao we had a big thunder storm go through. Lasted a few hours as it was slow moving. Dropped 50mm of rain on us. The winds changed direction like crazy. We only had about 30kts but in bursts from every direction of the compass. Our boat was being moved around quite a lot as the new wind burst came in from another direction. The snubber was working hard. We would never be without our snubber.

 

[NormanS]

Our 13.4m 19 tonne boat benefits from a 12 metre long snubber. We wouldn't anchor without one. We have 60m of 10mm chain and an additional 50m of anchorplait. I can confirm that the conditions we anchor in the snubber is a valuable addition to our anchoring system. As I look around the anchorage we are currently in I would estimate the number of boats that don't have snubber fitted it less than 10% of boats

With a boat the size of your one, I would be using heavier chain. But that's just my personal opinion, and please don't take that as criticising your choice. I do find it telling that you feel the need to use a long snubber. Just for interest, do you still rig your snubber if you're anchored with all 60m of chain out, and using your anchorplait?
Your survey of the proportion of boats using "snubbers" doesn't differentiate between the normal short snubber, to take the load off the windlass, and long snubbers, so doesn't really tell us anything.
I have yet to see a ship using a long snubber, but they all have the means to take the load off the windlass.

 

[boomerangben]

It is interesting there are lots of views on chain sizing, strength, elasticity and so on but who actually knows what loads are taken by their rodes? Without that key piece of information, comparing each other’s tackle is a bit moot. In an ideal world we would know what sort of loads we expect, have an idea of the elasticity of our snubber/catenary and therefore be able to size to suit.

Neeves’ cats cradle is an engineering marvel and clearly something hehas taken much time and effort to perfect. It strikes me that you need to be all over the chaff factor with stretchy rope passing through metal rings. It doesn’t look very simple to me but then I’ve never sailed a cat. Lots of heavy chain works well for others. Not terribly well engineered maybe be but neither is a sledge hammer but it gets the job done. Mixed rode works well for my application but at the smaller end of the scale it is easier since the smallest anchor and chain is way over spec’d and rope that is comfortable to haul means a bigger diameter than needed as well.
Horses for courses of course, but it strikes me that none us really understand the loads - if you don’t know the course, your can’t choose the right horse.

 

[Supertramp]

It is interesting there are lots of views on chain sizing, strength, elasticity and so on but who actually knows what loads are taken by their rodes? Without that key piece of information, comparing each other’s tackle is a bit moot. In an ideal world we would know what sort of loads we expect, have an idea of the elasticity of our snubber/catenary and therefore be able to size to suit.

Neeves’ cats cradle is an engineering marvel and clearly something hehas taken much time and effort to perfect. It strikes me that you need to be all over the chaff factor with stretchy rope passing through metal rings. It doesn’t look very simple to me but then I’ve never sailed a cat. Lots of heavy chain works well for others. Not terribly well engineered maybe be but neither is a sledge hammer but it gets the job done. Mixed rode works well for my application but at the smaller end of the scale it is easier since the smallest anchor and chain is way over spec’d and rope that is comfortable to haul means a bigger diameter than needed as well.
Horses for courses of course, but it strikes me that none us really understand the loads - if you don’t know the course, your can’t choose the right horse.

I agree about the loads - I know there is "a lot" on my chain in strong winds but I have no idea what the snatch loads in gusts are, the effect of waves etc. which steady load testing doesn't cover. I suspect some of us size rode and anchors on the basis of overdoing it to give a safety factor (discussed many times). But there don't seem to be many cases where the core materials fail suggesting few of us are anywhere near the limits. Poor connectors and chafe seem much more likely to cause fails. Neeves point is that known or defined quality materials used sensibly let you go lighter which is important in some applications (like his). For me I do not want to be over worrying about anchor gear when conditions get bad.

I think that developing your own equipment and system for your boat through experience and shared knowledge is a good way to go and will lead to a multiplicity of answers.

If you never expect to be anchoring in adverse and uncertain conditions then don't worry - a normal anchor, 30m of chain and 30m of rope will cover occasional stops.

 

[RunAgroundHard]

The loads have all been calculated and measured. The data is available to view from many sources, both attached to YBW threads and externally.
You need to read more anchor threads in the archive.

 

[Tranona]

It is interesting there are lots of views on chain sizing, strength, elasticity and so on but who actually knows what loads are taken by their rodes? Without that key piece of information, comparing each other’s tackle is a bit moot. In an ideal world we would know what sort of loads we expect, have an idea of the elasticity of our snubber/catenary and therefore be able to size to suit.

A lot less than you think. The key argument for heavy chain is the catenary effect, but as shown regularly (including earlier in this thread) this generally disappears between 25-30 knots of wind and the chain becomes straight. Its only function then is to connect the boat to the anchor, so it only has to be strong enough to cope with the holding power of the anchor. How often do you hear of chain breaking? - the weak point (as again has been demonstrated many times) is the connectors, principally shackles rather than the chain. So, as geem demonstrates once the damping effect of chain catenary is lost the only way of dealing with shock loads, changes of wind direction etc is with a snubber.

The "bigger and heavier" is a long held belief that a heavier anchor with heavier chain will set better, but again once this belief is rigorously tested it is found not to be the case. The anchor does not care what is pulling it when it sets as it is only the load that is applied that matters. So why does this belief persist? my view is that it is simple human behaviour. The vast majority if people prefer endorsement of their belief rather than challenge - and the typical "I have been anchoring for 40 years and never had a problem" is taken as confirmation that the belief is correct - but the challenge would be to determine whether smaller chain (and anchor) would perform equally well. The science and empirical testing shows that in many cases it would. The vast majority of anchoring takes place in relatively benign conditions that place minimal demands on the gear, other than getting the anchor to set properly. New generation anchors have made great strides in this direction, setting better and having higher holding power. That being the case surely it is reasonable to challenge prior assumptions about the rest of the gear in the anchoring system?

There is also something to be said about the anchoring traditions that led to beliefs. In the UK most (but not all) anchoring is in mud or sand and in benign conditions and the "traditional" anchors such as the CQR, Danforth, Bruce are generally adequate. However once people started sailing and anchoring in different environment, particularly the rush to the Med and Caribbean 30 years ago they quickly found the shortcomings of such anchors, hence the rapid development of superior anchors. Not surprising that almost all the new developments came from outside the UK and that they are informed by science and not tradition.

To answer your last sentence, that information is freely available and widely written up in the yachting press particularly by Jonathan and Vyv Cox. So why are people reluctant to accept the science and change their anchoring equipment? partly, as expressed by some on this thread because they don't feel the need or don't think the benefits are worth it and partly because changing is expensive. Windlass, chain and anchor is £2000+ on a 10m boat to replace perfectly serviceable existing gear. So you can understand the OP in his quest to find a better way of dealing with the limitations of his current set-up rather than chucking it away and starting again. On the other hand if you follow the liveaboard cruiser scene you will find many who have done just that simply because of the huge inadequacy of the original set up for the new conditions.

 

[Supertramp]

But for the less well read there does not seem to be a simple answer to what anchor, rode and system to use. Unless it really doesn't make that much difference....

 

[geem]

A lot less than you think. The key argument for heavy chain is the catenary effect, but as shown regularly (including earlier in this thread) this generally disappears between 25-30 knots of wind and the chain becomes straight. Its only function then is to connect the boat to the anchor, so it only has to be strong enough to cope with the holding power of the anchor. How often do you hear of chain breaking? - the weak point (as again has been demonstrated many times) is the connectors, principally shackles rather than the chain. So, as geem demonstrates once the damping effect of chain catenary is lost the only way of dealing with shock loads, changes of wind direction etc is with a snubber.

The "bigger and heavier" is a long held belief that a heavier anchor with heavier chain will set better, but again once this belief is rigorously tested it is found not to be the case. The anchor does not care what is pulling it when it sets as it is only the load that is applied that matters. So why does this belief persist? my view is that it is simple human behaviour. The vast majority if people prefer endorsement of their belief rather than challenge - and the typical "I have been anchoring for 40 years and never had a problem" is taken as confirmation that the belief is correct - but the challenge would be to determine whether smaller chain (and anchor) would perform equally well. The science and empirical testing shows that in many cases it would. The vast majority of anchoring takes place in relatively benign conditions that place minimal demands on the gear, other than getting the anchor to set properly. New generation anchors have made great strides in this direction, setting better and having higher holding power. That being the case surely it is reasonable to challenge prior assumptions about the rest of the gear in the anchoring system?

There is also something to be said about the anchoring traditions that led to beliefs. In the UK most (but not all) anchoring is in mud or sand and in benign conditions and the "traditional" anchors such as the CQR, Danforth, Bruce are generally adequate. However once people started sailing and anchoring in different environment, particularly the rush to the Med and Caribbean 30 years ago they quickly found the shortcomings of such anchors, hence the rapid development of superior anchors. Not surprising that almost all the new developments came from outside the UK and that they are informed by science and not tradition.

To answer your last sentence, that information is freely available and widely written up in the yachting press particularly by Jonathan and Vyv Cox. So why are people reluctant to accept the science and change their anchoring equipment? partly, as expressed by some on this thread because they don't feel the need or don't think the benefits are worth it and partly because changing is expensive. Windlass, chain and anchor is £2000+ on a 10m boat to replace perfectly serviceable existing gear. So you can understand the OP in his quest to find a better way of dealing with the limitations of his current set-up rather than chucking it away and starting again. On the other hand if you follow the liveaboard cruiser scene you will find many who have done just that simply because of the huge inadequacy of the original set up for the new conditions.

Very well written. I would add that I think many people looks at all anchoring through their own eyes and experience. Some people can't imagine that they need such devices as long snubbers or new generation anchors. If they sail in an area where they don't need to deal with tough seabed conditions or swell at anchor, very strong winds and squalls then they struggle to see why others need such equipment.
The easiest seabed for good holding is mud and or sand. Like you say, lots of that in the UK

 

[NormanS]

But for the less well read there does not seem to be a simple answer to what anchor, rode and system to use. Unless it really doesn't make that much difference....

Exactly. I really wish that people wouldn't try to make anchoring sound so much more complicated than it is. It has the effect of putting people off trying, learning, and gaining experience. When I started cruising, there were no yacht pontoons or visitor's moorings. Anchoring was the only option, and it is still my preferred choice.

 

[geem]

But for the less well read there does not seem to be a simple answer to what anchor, rode and system to use. Unless it really doesn't make that much difference....

My view would be any new generation SHHP anchor selected to be the correct size/weight for your boat with correspondingly sized chain. This will be far superior setting to an old gen anchor. Add a snubber of course?

 

[geem]

Exactly. I really wish that people wouldn't try to make anchoring sound so much more complicated than it is. It has the effect of putting people off trying, learning, and gaining experience. When I started cruising, there were no yacht pontoons or visitor's moorings. Anchoring was the only option, and it is still my preferred choice.

Your describing most of the Caribbean

 

[doug748]

Very well written. I would add that I think many people looks at all anchoring through their own eyes and experience. Some people can't imagine that they need such devices as long snubbers or new generation anchors. If they sail in an area where they don't need to deal with tough seabed conditions or swell at anchor, very strong winds and squalls then they struggle to see why others need such equipment.
The easiest seabed for good holding is mud and or sand. Like you say, lots of that in the UK

Not quite that they can't imagine that they need such things as long snubbers of new generation anchors. It's just that they don't need them - or even to worry if they are any use or not.

What they need is what most Channel sailors have, strong cheap chain, plenty of it and an anchor proportionate to the boat. Plus a back up 30mtrs of nylon and short bit of stretchy rope to cut the rumble on the chain and for use in the unlikely event of it starting to jar.

Job done. Norman has it sussed.

.

 

[Arcady]

Neeves - I’d like to hear your views of using a shorter nylon snubber but incorporating a rubber mooring snubber. Does the latter help make up for the shorter length of the former?

 

[geem]

Not quite that they can't imagine that they need such things as long snubbers of new generation anchors. It's just that they don't need them - or even to worry if they are any use or not.

What they need is what most Channel sailors have, strong cheap chain, plenty of it and an anchor proportionate to the boat. Plus a back up 30mtrs of nylon and short bit of stretchy rope to cut the rumble on the chain and for use in the unlikely event of it starting to jar.

Job done. Norman has it sussed.

.

Not if he sails here he doesnt?. He might become a drug queen?

 

[Tranona]

Not quite that they can't imagine that they need such things as long snubbers of new generation anchors. It's just that they don't need them - or even to worry if they are any use or not.

What they need is what most Channel sailors have, strong cheap chain, plenty of it and an anchor proportionate to the boat. Plus a back up 30mtrs of nylon and short bit of stretchy rope to cut the rumble on the chain and for use in the unlikely event of it starting to jar.

One man's meat is another man's gravy (or whatever the saying is). Your view of "strong, cheap chain" and "anchor proportionate to the boat" may be very different from mine. You won't get much help from the size charts either as they all give wide or very wide ranges in terms of boat size and ignore strength and grade of chain and in many cases size as well jimmygreen.com/Anchors/79764-lewmar-delta-anchor-galvanised In another version they suggest chain sizes with 8mm covering from around 28-44' and 10mm from 44' up to nearly 60'. So many variables within these recommendations it is down to individual judgement and inevitably given the "heavier and bigger is better" mindset that dominates there is a tendency to overspecify.

Given the availability of so much data on performance of chain and anchors these days it is easier to make an informed choice in relation to your individual circumstances.

 

[Neeves]

Norman, no need for you to read this, its wordy, it repeats much of what has been said by me and others - no need to complain - you have been warned.

Neeves - I’d like to hear your views of using a shorter nylon snubber but incorporating a rubber mooring snubber. Does the latter help make up for the shorter length of the former?

In terms of snubbing ability then a rubber dog bone thing has the equivalent snubbing ability as 3m of appropriately sized nylon. Prof Knox and I both tested dog bone things and came to the same conclusion. You could have 10m of rope from your transom through the bow roller - it will be the equivalent of 3 dog bone things. Run the snubber through those devices you use to tidy up furling lines and it will be all neat, manage the wear points - you are good to go.

So if you buy a rubber dog bone thing designed for 12mm rope then it has the same ability to absorb a snatch as 3m of 12mm rope. I know which is cheaper.

Rubber dog bone things come into their own in a pontoon application where you might not be able to rely on a long warp.

But - I am trialing using them attached to my long snubbers. My reasoning is that on your car you have a number of devices to make the ride more comfortable, springs, shock absorbers, the tyres, the foam in the upholstery. They each remove a different shock or snatch. Why not employ the same thinking for the rode. I have some catenary but rely largely on nylon. A little snatch is quickly accommodated by the chain, a bigger snatch is accommodated by the chain and snubber. The dog bone does fit in - but I don't notice the difference - nylon is cheaper.

I don't know if you can access this, it might be behind a paywall

Anchor Testing and Rode Loads - Practical Sailor

I measured snatch loads at different scopes using our catamaran. I also compared our cat, in terms of windage, and our windage is similar to that of a Bavaria 45. I have drawings of the Bav and and our cat. The 2 yachts are very different, and different weight - and the reality may be you cannot compare, at all. But I tried.

I simply anchored at different scopes during the development of a summer Seabreeze and measured rode tension (I removed all elasticity) vs wind speed - upto 35 knots. I did not go beyond 35 knots as the snatch loads were frightening and our sea breezes don't develop more strongly than 35 knots anyway.

There are also a number of spread sheets, largely developed in America, of yacht size vs tension in the rode. A google search throws up a number of different examples. With the Practical Sailor data and some of these spread sheets there is a wealth of information - but you do need to extrapolate for your yacht. Whatever source you find and use for your desire to quantify rode tensions - they will not approach the hold of your anchor. My maximum measured snatch loads were 650kg at 35 knots at short scope - so worst case scenario (days of work for one result ). The hold of our and most modern 15kg anchors is around 2,000kg in nice clean sand. That 650kg snatch on the rode was the same as the snatch on the anchor.

At the end of the day personal experience is the answer. But a length of nylon, for a 40' yacht 10mm is fine, buy 15m. If you like what you feel you can then optimise.

Attach it to you rode with a hitch, attach to your yacht at the bow roller - and try various lengths of rope and judge the impact (or lack of impact). The 10m of 10mm nylon you can use as a mooring warp later. You need to try it in a decent breeze. Try diffrent scopes, easily done, set your anchor and deploy more or less chain. The benefits are greatest when you are on less than adequate scope - but cannot deploy more scope because there is a yacht behind you or shallow or rocks. At about 5: 1 scope in 30 knots your rode will look straight (its not but it has lost most ability to offer you any comfort) and then nylon is your saviour.

You can worry about abrasion later - its not a big issue if you manage it correctly - but snubbers fail where they rub - even though you can see no damage - the damage is internal in the construction (so carry spares). The advantage of climbing rope is that the outer cover is specifically designed to be abrasion resistant and the core is designed to offer elasticity (and in Oz I could repurpose rope to trial my ideas without spending money - and I then bought new climbing rope). The LFRs on my bridle plate may cause abrasion, but you can move the 'wear' point easily, just mark it after a strong wind event and deploy more or less rope next time.

The reality is that we all try to avoid strong wind events. We plan to go out with the family at the weekend but as the weekend gets closer the forecast changes and we stay at home. But we all get caught out - sometime we can scurry home, sometimes we can move to somewhere less windy (which is what the wise did for the Scilly storm - listening to weather forecasts is a much better answer than sitting it out) - and sometimes we are caught short - the storm in the Scilly Isles last year, the storm in the Med for which I provide links to both and everyday events in the Carib. When you cannot deploy more rode, or don't have more to deploy 10m - 30m of cheap nylon will suffice.

Storm tactics at anchor: Surviving gales in Scilly - Yachting Monthly

Safety at Sea: Surviving a Powerful Storm in the Med

The account of the Med storm was all about use, or not, of storm snubbers and the inadequacy of the system being used. The article simply underlined to me that there had to be simple answers - and not a series of denials. I would never suggest I have the perfect answer, there will be developments but I don't think ignoring what actually happens is valid. I'm also conscious that many find that whatever they have for ground tackle is adequate and totally different to my deliberations - this is fine by me - go and tell it to the people who lost yachts in the Scilly Islands or the Med - they need your advice.

Frankly I don't think carrying 100m of 10mm chain on a 11m AWB is the only answer.

Jonathan

 

[Neeves]

I referenced American spread sheets of tension vs yacht size. This is possibly the most widely respected - but there are others. Units are Imperial.

This spread sheet (and others) makes assumption - but I don't know what they are.

I mentioned I measure snatch loads of 650kg at 35 knots for our cat and suggested we had the windage of a 45' Bav - that's not far off an extrapolation, mental arithmetic, of the data given. But it does not differentiate between the flighty AWB's of the last 20/30 years that most of us sail (anything built by the current clutch of boat builder and their accountants, Benny, Bav, Hans, Jenny et al) and chunky yachts.




I also add this graph as I think it pertinent.

This graph is a bit restrictive as hopefully as the tensions, in kg, increase more chain would be deployed. But it underlines the limited usefulness of chain - but if you had both the chain and the nylon.....and more nylon



G30, 8mm chain has a UTS of 3,200kg, G 40,4000kg and G70 7,000kg. Our 6mm HT chain has a tested strength of 4,400kg the same as the tested strength of the 8mm it replaced. According to the ABYC data - you are very unlikely, and definitely unlucky, to ever test the strength of your chain (though it will begin to stretch at about half of its break strength).

Jonathan