WindyWindyWindy
Active member
Actually this links to the series drogue thread. It seems that your cleats are likely not good for 2000Kgs anyway.
The 2000 kg holding myth
- Thread starter noelex
- Start date
zoidberg
Well-known member
zoidberg
Well-known member
I'm quite intrigued by the assertion by TWO of the more reliable contributors here that about 500kg force is probably the maximum anchor load I/we are ever likely to experience.
That suggests to me that I need only a comparable anchor rode, beefed up just a tad to allow for modest chafe and degradation with age, etc.
It seems, from several online strength charts, that 3mm dyneema would suffice, but that a 4mm dyneema rode would give a Safety Factor of >4:1
And it's one hell of a lot lighter than 10mm galv chain!
H&S wonks on here like a bit of Safety Factor, so that would seem to keep everyone happy. As Spock would say, 'It's only logical, captain.'
What d'you reckon?
That suggests to me that I need only a comparable anchor rode, beefed up just a tad to allow for modest chafe and degradation with age, etc.
It seems, from several online strength charts, that 3mm dyneema would suffice, but that a 4mm dyneema rode would give a Safety Factor of >4:1
And it's one hell of a lot lighter than 10mm galv chain!
H&S wonks on here like a bit of Safety Factor, so that would seem to keep everyone happy. As Spock would say, 'It's only logical, captain.'
What d'you reckon?
tomaz_slo
Member
Actually it's not a question but brain storming question..
I read a lot of threads regarding anchors, schackles, swivels, chain, rope, but nobody have concern about cleats which, on my opinion, might be weakest point.
I am using snubber, connected to the both of bow cleats..
And why would I pay attention on schackle breaking load (1 tone or 2 tones) if I know that cleat will be pulled out (with or without GRP piece) way ahead of that....
Neeves
Well-known member
If you are using shackles with a breaking load of 1t or 2t then your yacht is quite small. The recommendation for a yacht of say, 35'-40' might be a 3/8th" shackle with a breaking load of 10t (the Working Load Limit might be 2t). But a heavier 35' yachts might use bigger shackles and lighter 40' yacht smaller shackles..... Maybe if you told us what yacht you have we might be better able to answer your question.
If you have doubts over the strength of your cleats then the easy solution is simply to add backing plates, which normally would not be unusual nor difficult to install.
I'd comment that cleat failure is uncommon - I don't recall anyone reporting same over the last 20 years. Bow, amidship and stern cleats seem to be pretty bulletproof.
We had a locally made 38' cat. A competitive cat approx same spec was built in Vietnam and they were shipped out as deck cargo. Loading to deck was completed using a crane and slings to the bow cleats, one on each bow. The deck cleats did not fail.
Jonathan
zoidberg
Well-known member
'Small is beautiful'....
I'm thinking 'the recommendation' for shackles of Average Breaking Load 10t is rather OTT when the max load imparted through the anchor and gear is <500kg.
Perhaps 'the recommendation' is more related to over-selling than concern for underspecifying....
As for security of cleats, I've sailed on more than a couple of Brit-built boats with jibsheet cleats secured by nothing more than nuts - and that's just bare nuts!
I suspect that, if most JenBenBav/AWB smallcraft were lifted by their bow cleats, the keels - and likely the hulls, too - would fall off, leaving the deck dangling on high.
B27
Well-known member
Now and then, yachts break free from moorings in gales.
Never heard that it's the cleat that fails.
One mooring contractor I chatted to was estimating that the broken worn chains he'd seen were good for a few tons, based on his experience of having broken one or two pulling sinkers out of the floor.
I've heard stories of anchor chain deforming to the point where it goes stiff, and or breaking, so I think it's possible for a medium sized yacht to exert more than a ton or two, in storm conditions.
The modern fashion for a short skinny bit of second hand nylon as a snubber seems likely to put a big shock load on things when the snubber breaks and then the chain goes tight with a bang.
I do know people who've broken stuff towing boats, get it wrong and the waves can cause the warp to go tight with a bang and something's got to give if the rope's too 'high modulus'.
Most bow cleats are held on with several bolts in shear, not exactly fragile.
I think a well buried anchor can probably create very high instantaneous forces, it might drag, but the sand and water mix it lives in probably looks super viscous and won't yield instantly to a shock load?
Never heard that it's the cleat that fails.
One mooring contractor I chatted to was estimating that the broken worn chains he'd seen were good for a few tons, based on his experience of having broken one or two pulling sinkers out of the floor.
I've heard stories of anchor chain deforming to the point where it goes stiff, and or breaking, so I think it's possible for a medium sized yacht to exert more than a ton or two, in storm conditions.
The modern fashion for a short skinny bit of second hand nylon as a snubber seems likely to put a big shock load on things when the snubber breaks and then the chain goes tight with a bang.
I do know people who've broken stuff towing boats, get it wrong and the waves can cause the warp to go tight with a bang and something's got to give if the rope's too 'high modulus'.
Most bow cleats are held on with several bolts in shear, not exactly fragile.
I think a well buried anchor can probably create very high instantaneous forces, it might drag, but the sand and water mix it lives in probably looks super viscous and won't yield instantly to a shock load?
Neeves
Well-known member
The 10t UTS for a 3/8th" shackle is on the basis, really crude, that the shackle fits the appropriately sized chain and hole in the anchor shank (bow through hole). Additionally this size would be typical for an anchor for a 35' - 40' yacht, say 15kg/20kg. The UTS of the recommended shackle, a G80 shackle, of 10t results in a WLL of 2t. However if the shackle is side loaded the WLL is reduced by 50% to 1,000kg. 1,000kg is near the WLL of the chain that is being used, 8mm G30 chain has a WLL of 750kg.'Small is beautiful'....
I'm thinking 'the recommendation' for shackles of Average Breaking Load 10t is rather OTT when the max load imparted through the anchor and gear is <500kg.
Perhaps 'the recommendation' is more related to over-selling than concern for underspecifying....
As for security of cleats, I've sailed on more than a couple of Brit-built boats with jibsheet cleats secured by nothing more than nuts - and that's just bare nuts!
I suspect that, if most JenBenBav/AWB smallcraft were lifted by their bow cleats, the keels - and likely the hulls, too - would fall off, leaving the deck dangling on high.
So the G80 x 3/8th" shackle, the anchor size, the chain size are all around the WLL of 750kg/1,000kg and the yield strength of the chain, when it starts to deform, is 2 times WLL. Cheap shackles that you might see in the local hardware store would possibly have a UTS of 5t, WLL of 1,000kg - but the side loading would reduce the WLL to 500kg, well below that of the chain. G80 shackles cost peanuts, compared to the cost of the chain - more sensible to make the chain the weak link. You can buy Crosby G80 shackles from Tecni in the UK - there is no excuse to not buying one.
But a rated, 3/8th" G80 shackle is not over strength - its about right. Shackle are reported to fail, but not G80 shackles. Chain failure has not been mentioned on YBW for decades - chain strength, if bought to the recommended size by chain spread sheets, is equally strong. Since the introduction of the new rash of anchors Rocna, Spade etc etc reports of anchors dragging have disappeared as relics of history (and by and large - the demand that people oversize their anchor has been debunked). Reports of cleat failure are still as rare as dragon's teeth. The market place has learnt and swivel failure is also a thing of the past.
Snubbers do fail, with the sound much like gunshot (so you should carry a spare). But your rode should have back up securement, commonly some sort of chain lock using the bow roller to ensure the snatch loads are not instantly transferred to the windlass. The bow of a yacht is possibly one of the strongest parts of yacht construction - use that extra strength to your advantage (and if you have a flimsy bow - beef it up with some reinforcing).
If your snubber is excessively thin, or too short (ideal would be deck length) and have no elasticity - it will fail quickly. But a correctly sized and installed snubber tames snatch loads and it is well worth doing it correctly.
Basically all the tools, the data, the practices for anchoring and the choice of anchor is all available on YBW. Most people appear to follow the recommendations but there is still healthy debate - when recommendations are reiterated and new ideas aired. Most members on YBW saw the light, years ago, hence the absence of reports of failure - but we have new members who appear to be subjected to dated mantra - who still need to see the light.
There will always be room and need for anchor threads
Jonathan
Zoidberg is correct - a shackle with a 2t WLL is ridiculous for a 35' modern AWB. But every reputable shackle maker, Crosby, Campbell, Peerless, Yoke etc etc all, without exception, clearly point out on their websites that the WLL is degraded by 50% if the shackle is side loaded. Its the owner's decision but a G80 shackle is so easy to buy there is no reason to ignore the advise and recommendations. For those who have downsized their chain - from, say, 8mm to 6mm by using HT chain - the 3/8th" shackle will not fit the chain - use an Omega link as an enlarged link - and you are good to go and sacrifice no strength at all.
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zoidberg
Well-known member
There speaks a True Believer!There will always be room and need for anchor threads
Since I'm in 'the mood' tonight, let's examine this WLL business. This concept derives from the LIFTING industry and its justifiable concern with proper working-practices' H&S, due to workers standing near and/or under the loads, and chain-lifting components being subjected to all imaginable forms of abuse.
I cannot quite see Jon Neeves, or myself, remotely likely to be at risk of an errant anchor falling on our heads.
I'm of the view that a chain or shackle's MinBreakLoad/MBL is of better relevance to us, and factor in a relevant margin.
Similarly, the LIFTING industry has formulated guidance - some of it mandatory - on what they specify as 'side loading'.... usually associated with chain or webbing lifting slings.
It is IMHO simplistic and not entirely helpful to adopt standards and practices from other industries and environments without a clear understanding of the context.
Harumph!
Neeves
Well-known member
Actually, if you are blaming me, I do not devise Working Load Limits - these are devised by, the chain maker (who knows his galvanised chain is being used in an anchor rode) or a shackle maker (whose products have been largely replaced by other devices (like Omega Links) in the lifting industry. If you read the small; print for G30 galvanised chain it specifically says "Not to be used for Lifting". Specifically Omega links, lifting chain and other bits and pieces used in lifting are almost all universally sold to a 4:1 safety factor whereas (seldom used) shackles (often called 'anchor' shackles) are supplied with a 5:1 safety factor.There speaks a True Believer!
Since I'm in 'the mood' tonight, let's examine this WLL business. This concept derives from the LIFTING industry and its justifiable concern with proper working-practices' H&S, due to workers standing near and/or under the loads, and chain-lifting components being subjected to all imaginable forms of abuse.
I cannot quite see Jon Neeves, or myself, remotely likely to be at risk of an errant anchor falling on our heads.
I'm of the view that a chain or shackle's MinBreakLoad/MBL is of better relevance to us, and factor in a relevant margin.
Similarly, the LIFTING industry has formulated guidance - some of it mandatory - on what they specify as 'side loading'.... usually associated with chain or webbing lifting slings.
It is IMHO simplistic and not entirely helpful to adopt standards and practices from other industries and environments without a clear understanding of the context.
Harumph!
Chain makers if they feel the safety margins are invalid can sell their chain to whatever safety factor they want - but they would need to justify any changes, having accepted 4:1 for decades.
However I do agree that the safety factors from which the WLL is derived, such as 750kg for 8mm G30 galvanised anchor chain, is a real phurphy and actually of no value to the owner of a yacht - as he has no idea the tensions that might be expected in a rode. I also suspect that many owners, using 8mm chain, have no idea of its UTS, its Proof Load expectations and its WLL - what he does know is that if he checks - the 8mm size is the one recommended for his yacht.
The other factor is that the chain size dictates the shackle size (physically dimensions) and if he purchases wisely his G80 shackle is comfortably stronger than his chain, for 8mm chain the shackle (with all its caveats) has a WLL of 1t. And that G80 3/8" alloy shackle with a UTS of 10t, WLL of 2t in a straight line pull, or 1t if side loaded - conveniently fits both his chain and anchor.
Finally - In terms of strength the sizes recommended in the spread sheets are 'about right' however they were developed - chain failure is not something we need worry about (even though weight, or catenary, might be part of the foundation of the spread sheets - but catenary is so twentieth century
- now that we have accepted snubbers ..... Now Mr Zoidberg
Are you willing to justify and support replacement of 8mm chain with 6mm chain, and 8mm as replacement for 10mm chain ...... as that might be the inevitable development from your.....Harumphing.
. Most people I see disagree with your premise, they either buy against the spread sheets, some, many go bigger - none go smaller (unless its HT chain.
Jonathan
Bouba
Well-known member
What is the difference between an omega link and a shackle ?
NormanS
Well-known member
Somewhere in your above essay, you mention "snatch loads".The 10t UTS for a 3/8th" shackle is on the basis, really crude, that the shackle fits the appropriately sized chain and hole in the anchor shank (bow through hole). Additionally this size would be typical for an anchor for a 35' - 40' yacht, say 15kg/20kg. The UTS of the recommended shackle, a G80 shackle, of 10t results in a WLL of 2t. However if the shackle is side loaded the WLL is reduced by 50% to 1,000kg. 1,000kg is near the WLL of the chain that is being used, 8mm G30 chain has a WLL of 750kg.
So the G80 x 3/8th" shackle, the anchor size, the chain size are all around the WLL of 750kg/1,000kg and the yield strength of the chain, when it starts to deform, is 2 times WLL. Cheap shackles that you might see in the local hardware store would possibly have a UTS of 5t, WLL of 1,000kg - but the side loading would reduce the WLL to 500kg, well below that of the chain. G80 shackles cost peanuts, compared to the cost of the chain - more sensible to make the chain the weak link. You can buy Crosby G80 shackles from Tecni in the UK - there is no excuse to not buying one.
But a rated, 3/8th" G80 shackle is not over strength - its about right. Shackle are reported to fail, but not G80 shackles. Chain failure has not been mentioned on YBW for decades - chain strength, if bought to the recommended size by chain spread sheets, is equally strong. Since the introduction of the new rash of anchors Rocna, Spade etc etc reports of anchors dragging have disappeared as relics of history (and by and large - the demand that people oversize their anchor has been debunked). Reports of cleat failure are still as rare as dragon's teeth. The market place has learnt and swivel failure is also a thing of the past.
Snubbers do fail, with the sound much like gunshot (so you should carry a spare). But your rode should have back up securement, commonly some sort of chain lock using the bow roller to ensure the snatch loads are not instantly transferred to the windlass. The bow of a yacht is possibly one of the strongest parts of yacht construction - use that extra strength to your advantage (and if you have a flimsy bow - beef it up with some reinforcing).
If your snubber is excessively thin, or too short (ideal would be deck length) and have no elasticity - it will fail quickly. But a correctly sized and installed snubber tames snatch loads and it is well worth doing it correctly.
Basically all the tools, the data, the practices for anchoring and the choice of anchor is all available on YBW. Most people appear to follow the recommendations but there is still healthy debate - when recommendations are reiterated and new ideas aired. Most members on YBW saw the light, years ago, hence the absence of reports of failure - but we have new members who appear to be subjected to dated mantra - who still need to see the light.
There will always be room and need for anchor threads
Jonathan
Zoidberg is correct - a shackle with a 2t WLL is ridiculous for a 35' modern AWB. But every reputable shackle maker, Crosby, Campbell, Peerless, Yoke etc etc all, without exception, clearly point out on their websites that the WLL is degraded by 50% if the shackle is side loaded. Its the owner's decision but a G80 shackle is so easy to buy there is no reason to ignore the advise and recommendations. For those who have downsized their chain - from, say, 8mm to 6mm by using HT chain - the 3/8th" shackle will not fit the chain - use an Omega link as an enlarged link - and you are good to go and sacrifice no strength at all.
Was your rode subjected to snatch loads? Mine isn't.
Were you anchoring in very shallow water, subject to wave action?
Was your gear so light that it has no useful catenary?
Did your boat have disproportionate windage compared to its underwater shape?
Even when anchored in severe gale force winds, when there is a considerable load on my rode, it is not subjected to snatch loads (in the generally accepted meaning of the term).
With bad weather expected, I normally choose anchorages with a reasonable depth of water, meaning that my chain gives a useful catenary. I don't anchor where the boat will experience significant waves, but unlike you I am seldom able to avoid the full strength of the wind. I try not to be anchored under high ground in strong winds, as it tends to be very squally, both in strength and direction.
Anchored in strong winds, I will often rig a riding sail, to cut down on yawing, with its resultant heeling. I don't like spilling my soup.
Earnest searching after truth.
WindyWindyWindy
Active member
.
Neeves
Well-known member
My rode is not subject to snatch loads as I use 2 snubbers (aka a bridle). I notice that other yachts, who do not use a snubber or one that is insufficiently elastic, thin or longer, can suffer snatch loads. This is not necessarily their fault - tight anchorages are often beset by bullets of wind that are funnelled down valleys or gaps in the trees. In calmer times these are balmy wind variations - in a storm and with limited space and inadequate snubbers - they can result in snatch loads. Because we commence our snubbers at the transom and had a 22' beam - we had long snubbers - well capable of managing snatch loads. Sadly not everyone reads my long posts on snubbers, in fact many are not even members, their loss - but the message is getting through.
Jonathan
zoidberg
Well-known member
Huh! You're no fun!Are you willing to justify and support replacement of 8mm chain with 6mm chain, and 8mm as replacement for 10mm chain ...... as that might be the inevitable development from your.....Harumphing.
I DID upcycle to shiny new 6mm high-test Gunnebo chain, accepting last year's argument. That was as much 'retail therapy' as religious fervour, but WTH.
There's still a pile of G30 x 8mm in good nick gathering dust in my polytunnel, waiting perhaps for me to acquire 'nothr project' that needs it.... oh, and a clutch of cheap-as-chips BigSodOff Low Friction Rings c/w big fat Softee Shackles, courtesy of AliExpress ( rated at a fabulous 45,000lbf ) that are looking for work.
Perhaps I should put together some Off-Road Recovery kits, against the unlikely event of me sliding into an Ozzie donga in a huge all-wheel drive truck.
Time for coffee....!
Neeves
Well-known member
In the lifting industry all the components are defined by strength, G80, G100 and G120. Components are also defined by size, metric chains are 6mm, 8mm, 10mm, 12mm - maybe larger. All 8mm components are made to the same size specification and it is impossible to use 6mm or 10mm components with 8mm components - they simply will not fit. All components are embossed with their size (6mm), strength 100 (aka 10) and are sometimes colour coded. You can tell at a glance if a 6mm G80 unit is part of an assembly of G120 units. This is unlike our components where anchor shanks are different thicknesses and different sized chain can fit the same shackles.
If you down size your chain, as we did, from G30 8mm to a galvanised G80 you still are subject to the same, or similar, rode tensions (so you use the same anchor and need the same shackle (because a smaller shackle would be insufficiently strong). That same shackle is now too big for 6mm chain. Historically you might have had a large chain link added to your rode - but this introduced other issues - and the answer is to use an Omega link.
This is a 15kg steel anchor shackle hole with a G80 3/8th" shackle (fits neatly, bow through the hole) joined to high tensile 6mm chain, the 6mm chain is stronger than the 8mm it replaces. The device to join the 6mm chain to the shackle is a 6mm omega link.
The clevis pin of the omega would accept a bigger chain link, say 8mm, but the jaw of the link is too small to accept the bigger link. The clevis is a tight fit, they tend to need to be hammered in, and they are secured with hammer in pins (you can see the 2 hammer in pin ends). The use of the Omega is 'single use' as they are difficult to disassemble.
This our chain after much use (Ive replaced the hammer in pins with cotter pins, I swap and change frequently as I test items and ideas.
Omega links come in different forms and some are called pear links, that one top row, second from left. Alternatives to Omega links are hammerlocks, the pale blue, large bright yellow and the green device. The top row, apart from the shackle, are all 6mm devices, pins are the same diameter, the jaw of the slot is less than 8mm. Omegas tend to be neat(er), and hammerlocks smoother - than shackles (that's a 3/8th" shackle). The darker blue Omega is 6mm, but it is an old design the version on the left is much neater.
Here I have played about with my Boomerang to accept Omegas, or Hammerlocks. The original Boomerang design was designed round 3/8th" shackles but it was a bit clumsy needing a shackle at each end of the boomerang and one on the anchor - all ready to catch on a bow roller. I even designed a Boomerang to attach directly to the chain - but it was a devil to assemble - so its in the pending bucket, awaiting more inspiration. These Boomerangs are made with Duplex stainless, a G60 steel except the top one is a G80, Bisplate 80 (the same strength as many anchor shanks).
Other differences
The strongest shackles are G80, the strongest chains in current use are G120.
Bow, "anchor' shackles are commonly sold galvanised, most lifting kit is painted or power coated - its part of marketing - I strip the coating off (paint stripper) and I have mine galvanised. But they last quite well, are not particularly expensive and you can chop them off and replace with a new unit.
The lifting industry is quite innovative - if you look at their lifting hooks, which we might use to secure a snubber to the chain rode, their designs make ours look like something out of The Ark.
If this is all too brief, I'm conscious NormanS has a short attention span
, I can elaborate.Jonathan
NormanS
Well-known member
But surely it's better to avoid snatch loads in the first place, rather than rigging gear to mitigate their effect?
RunAgroundHard
Well-known member
Of course, but if "snatch loads" occur, for whatever reason, I would have thought that being prepared to mitigate "snatch loads" would be a good idea. I see anchoring location, riding sails, heavier chain, dual anchors, bridles et cetera as just tools to be used when required.
You seam to be a person who applies your own thoughts and ideas based on your own experience. Yet when Neaves offers his advise, based on his own experience, you are fairly dismissive of it.
I assume that most folks who read anchoring threads on this forum can make their own minds up and take what they want from the anchoring advise offered.
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Neeves
Well-known member
You rig gear, its called lots of heavy chain, I had a modern catamaran and I wanted to keep it light so that I could sail fast. Lots of heavy chain costs money and weighs a lot. My rode was as light as you can get, 6mm chain for a yacht with the windage of a Bav 45, I replaced old fashioned catenary with 20th century elasticity, your catenary and my elasticity do exactly the same thing - absorb snatch loads, so you and I don't even know they were snatch loads. My snubbers are much more effective at absorbing snatch loads than your chain - I don't need to deploy as much rode as you do, for the same effect. My chain takes up little room as well as being lighter than your chain.
My nylon continues to manage snatch loads, chain has a finite ability.
You also rig a riding sail, to stop yawing, I use a bridle. My bridle improves scope and makes my rode 'closer' to parallel to the seabed. You need to deploy more chain to do the same thing (taking up more room in an anchorage).
The top 2 buckets hold our old chain, 50m of 8mm G30. The bottom 2 buckets contain our new chain, 75m of 6mm G80. The new chain is lighter than the old chain, its longer and its the same strength as the old chain.
We have snubbers made from recycling, free of charge, 2 x 30m of 12mm climbing rope which would otherwise go to land fill.
What's not to like?
Jonathan
Neeves
Well-known member
Get yourself some retired climbing rope add your Aliexpress Low Friction Rings, a pair of gloves, pack in neat canvas bag marked 'snowflake recovery kit' and you have an almost perfect snow vehicle recover kit (to which you alude in your post) - winter is coming - all you need are some snowflakes, preferably fresh.Huh! You're no fun!
I DID upcycle to shiny new 6mm high-test Gunnebo chain, accepting last year's argument. That was as much 'retail therapy' as religious fervour, but WTH.
There's still a pile of G30 x 8mm in good nick gathering dust in my polytunnel, waiting perhaps for me to acquire 'nothr project' that needs it.... oh, and a clutch of cheap-as-chips BigSodOff Low Friction Rings c/w big fat Softee Shackles, courtesy of AliExpress ( rated at a fabulous 45,000lbf ) that are looking for work.
Perhaps I should put together some Off-Road Recovery kits, against the unlikely event of me sliding into an Ozzie donga in a huge all-wheel drive truck.
Time for coffee....!
Jonathan
