Stainless steel anchor chain

BartW said:
imho and experience,

the scope should be long enough so that there is "alway's" at least several meters of chain on the seabed, in ANY sea condition,
if you don’t, and if the chain can 'lift' or move the stock, there is big risc that the anker doesn't hold.

this means indeed that in very strong wind, you need a lot of scope,
so if you don’t have enough scope in strong wind you need a very attentive watch-out !
and yes I know that a long scope is difficult or dangerous in case the wind turns direction,…

now having “always’s some length of chain on the seabed, means you always’s have some amount of catenary.
I can’t quantize this amount, but I am anyway a NON believer of a rubber snubber on my anker chain.
12mm chain and lots of scope gives me very good catenary in any wind condition.

And indeed, when you don’t have enough scope, and the chain is pulled tight,
AND the anker holds between rocks fe,
You will feel that the chain is pulling with peak loads on the boat,
But then again drop more chain or move the boat to somewhere else
Click to expand...

+1 absolutely.
I don't think I could sleep at night knowing that the chain was pulling directly on the anchor.
It is so obvious to me.
All anchors work best if the pull is horizontally across the sea bed.
It doesn't matter if the argeument is that modern anchors still work when pulled at an angle.
They all work better if pulled horjzontally so why push the limits.
I like my sleep.
 
Hurricane said:
+1 absolutely.
I don't think I could sleep at night knowing that the chain was pulling directly on the anchor.
It is so obvious to me.
All anchors work best if the pull is horizontally across the sea bed.
It doesn't matter if the argeument is that modern anchors still work when pulled at an angle.
They all work better if pulled horjzontally so why push the limits.
I like my sleep.
Click to expand...

It might be obvious but it's not true. In any wind that's noticeable you are always pulling directly on the anchor even when it's so light that lots of chain is resting on the sea floor. If you doubt this then try dropping the other end of the chain in an uncrowded anchorage in a couple of knots of winds and watch your boat going gently backwards no matter how much chain you pull out.
 
BartW said:
imho and experience,

the scope should be long enough so that there is "alway's" at least several meters of chain on the seabed, in ANY sea condition,
if you don’t, and if the chain can 'lift' or move the stock, there is big risc that the anker doesn't hold.

this means indeed that in very strong wind, you need a lot of scope,
so if you don’t have enough scope in strong wind you need a very attentive watch-out !
and yes I know that a long scope is difficult or dangerous in case the wind turns direction,…

now having “always’s some length of chain on the seabed, means you always’s have some amount of catenary.
I can’t quantize this amount, but I am anyway a NON believer of a rubber snubber on my anker chain.
12mm chain and lots of scope gives me very good catenary in any wind condition.

And indeed, when you don’t have enough scope, and the chain is pulled tight,
AND the anker holds between rocks fe,
You will feel that the chain is pulling with peak loads on the boat,
But then again drop more chain or move the boat to somewhere else
Click to expand...


I would love it if 12mm or 15mm or whatever chain had a catenary or that the vital low horizontal angle was created by catenary above a light to moderate wind force, or even that a chain with no anchor on the end would mostly hold a boat even in light winds, but none of that is so.

As I realise there are "believers" in chain on the seabed and believers in scope and anchors and we won't agree just by using our observation and experience I post a link and would be very interested in a site which helped explain your viewpoint in as logical a way. Obviously this link is biased as are many others but the points are explained well.

http://www.petersmith.net.nz/boat-anchors/catenary.php
 
Magnum said:
We are dealing with a 70ft+ 40 tonne boat here. Using 6mm chain would be ridiculous.
Click to expand...

The point is that it is the strength of the rode, it's elasticity for shock loads and abrasion resistance that counts and the weight is utterly irrelevant once any force is applied. So 6mm or 1mm kryponite wire would be fine if they had those qualities. If you are saying you need more than 6mm chain for it's breaking strain then of course I agree with you.
 
RupertW that's a plug for Rocna
The opening pic gives the game away -in 8m with 6-1 scope in a force 8 (40-60knots wind )
Who in there right mind would let out 48 M in that ?
As if you would go to the Antartic with 48M
Barts got 150M
I've got 70 M
SEE MY POST # 140
Where do Rocna get such low scopes from .? That's the flaw Rocna are proving @"bar tight " there anchor is better .
The Catenary lot are saying ,well iam saying my anchor just sits there ,never feels a twinge cos of the scope and weight of chain ,it just does not lift ,pull it .
A lot of the article seems to self justify some sort of wieght gain advantage -going small or shorter rode .
Most decent size MoBo .s can vary the total weight by over 10% by fluids alone -fuel /water /black water etc .
I,am 18,000 kg ex factory but can carry 2700 L of fliuds + up to 12 folks @ 79-80Kg each + cruising stores .
So I do not buy into saving what 200-300kg ? by going with a smaller chain or restricting my self to scope 6-1 in a gale ?

Fuel burn and £££ / mile is totally at my control with the throttles ,and or how many hrs I want to boat .

Then they say over 8-1 of scope , the boat would swing arround in a100m circle ---- so what !! -so does everybody else
If you visit post # 140 --- that's what happens ,chain was L shape on the bed in aF6 ---- but I was at 15-1 .

As I said I can not identify with this "bar tight "
Carry enough chain
Carry as heavey as poss -gypsy ,winch ,locker vol permitting
Let more heavey chain out .
Anchor in a sensible D ,
Bug out way before "bar tight " and shock loading the gear -anchor / windlass .
 
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I just don't get this. How is it so many argue that their chain will be pulling at all horizontally when it counts? Look over the bow in a blow. It is obvious. Dive in too if you wish. Over 25kt or so and the chain is bar tight unless you have the Queen Mary's anchor chain on your P68. I have a 12mm chain and it is bar straight. No catenary to speak of. None, nada, zilch and the boat is 100% reliant on the anchor's grip without the chain's help.

I suggested before that a heavier chain can help and can only be a good thing as it dampens down the peak load a little, but really it is of marginal help and practically only of use I low winds and if your anchoring technique is not great and the wind is not up, such that you can barely hold in that 25kt. So in reality it is not a lot of use, especially as you should be anchoring to hold in a nasty squall that may come in the night of much greater strength.
 
RupertW said:
I think we are in almost complete agreement except for one point on damping, so bear with me as I lay out the way that I think it works: The damping from chain is caused entirely by the catenary stretching out to near straight then dropping back again to a curve. So like any catenery is most useful in light to moderate winds in deeper water when you may get a couple of metres of straightening. But once the wind picks up only a tiny curve will be left giving perhaps only a few centimetres straightening available, each of which requires more and more huge forces - thus reducing damping to a couple of centimetres so not really worth it.

So with that in mind that's where I prefer a snubber which consists of a rubber snubber on a long nylon rope. Rubber snubber works in light to moderate and is most useful with just a little nylon out when anchoring off a harbour wall or in a veering anchorage. Once the wind gets up then if free anchoring I let a lot more nylon rope out so the rubber is almost permanently stretched out and the nylon provides the high tensile elasticity. Of course rubber snubber is a bit knackered after a particularly gale-y night or tow but is pretty cheap and sacrificial as well as useful nearly all the rest of the time.
Click to expand...

We are 100% agreed on all points.
 
Zing said:
I just don't get this. How is it so many argue that their chain will be pulling at all horizontally when it counts? Look over the bow in a blow. It is obvious. Dive in too if you wish. Over 25kt or so and the chain is bar tight unless you have the Queen Mary's anchor chain on your P68. I have a 12mm chain and it is bar straight. No catenary to speak of. None, nada, zilch and the boat is 100% reliant on the anchor's grip without the chain's help.

I suggested before that a heavier chain can help and can only be a good thing as it dampens down the peak load a little, but really it is of marginal help and practically only of use I low winds and if your anchoring technique is not great and the wind is not up, such that you can barely hold in that 25kt. So in reality it is not a lot of use, especially as you should be anchoring to hold in a nasty squall that may come in the night of much greater strength.
Click to expand...

Even if "bar tight", are you suggesting that the weight of 60m of 12mm chain compared to 60m of 8mm chain is irrelevant? The weight of the 12mm chain will exert a greater force downwards which in turn will offer resistance to the vessel moving away from the anchor. Otherwise as stated earlier in this thread, we would all be using high tensile cable.
 
Magnum said:
Even if "bar tight", are you suggesting that the weight of 60m of 12mm chain compared to 60m of 8mm chain is irrelevant? The weight of the 12mm chain will exert a greater force downwards which in turn will offer resistance to the vessel moving away from the anchor. Otherwise as stated earlier in this thread, we would all be using high tensile cable.
Click to expand...
Yes it will, but not by much, as in only a few mm of horizontal movement in strong wind. I worked it out once. At something like 50kt the stretch in the steel in the chain is more than the horizontal movement from catenary. A snubber of nylon will give a thousand or several thousand times more damping. That's the way to go.
 
Having gone through this debate in a previous thread, about the new anchor, I do indentify a different philosophy.

Mobo owners carry heavy chain and sometimes longer chain, because they can. 150m of 12mm has been quoted.

Yacht owners are more weight conscious and it would be most unusual for one to have 150m of chain and only someone with old fashioned ideas to carry chain of a link size larger than needed for the strength. Most would carry the link size recommended, for strength, and 100m max. Naby carry less than 100m of chain and will supplement with rope.

Yacht owners 'feel' restricted - the weight in the bow issue. Mobos can carry weight, or so they say, so they do not worry.

A Mobo with 150m of 12mm chain in 20m of water is a different animal oe the yachts of similar size with 12mm chain and 80m - in 20m of water.

Yacht owners who are to anchor where the ground tackle might be stressed MUST find other answers, than increasing weight or link and longer rode - the answer is very cheap and simple - snubbers

Mobo owners, who might, on commissioning, have a parsimonious chain, marginal link size and not much length simply throw money at the issue and buy more and more chain.

It is difficult to believe however that changing from 60m of 10mm chain to 150m of 12mm chain does not impact performance, it might be an acceptable difference but difficult to accept the difference is not there.

Because Mobo owners can simply add weight the concept of a smaller chain (but same strength of a bigger chain), which can be longer - offset that decrease in link weight with an increase in length - simply does not occur. The idea that a simple length of nylon can replace 50m of stainless has never been a concept of discussion. The idea that a snubber can replace catenary and and can be designed to work upto 70 knots, if you so wish, does not impinge on consiousness.

Smaller chain, same strength - offers the ability to use a smaller windlass, the windlass needs less deck reinforcing. The windlass will have a lower power draw, so smaller cables. The chain locker can be smaller, or possibly be better designed. The spare space freed up by using the smaller chain might be better used for something else. The down side is - you must use snubbers and they need to be about 30', or longer. For 70 knots you will need beefy snubbers - though Mobo owners, simply leave and go and find shelter elsewhere.

The limit of stronger chain is currently G100 - but its a bit pricey (not as much so as stainless) and realistically think G80.

But just because a 70' Mobo can carry 150m of 12mm chain does not mean its the best answer. Nor in fact might carrying 150m of 8mm HT chain be the best answer - but both options merit debate.
 
Two questions came up as the moon bathed Australia in a rather dull and cool light.

Swaged wire was suggested as perfectly safe as it is used in lifting.

Swaged wire is used in lifting and is subject to stringent and regular testing. Boat owners are not used to the idea of stringent, regular testing of any component - people would not do it - therefore there is a risk - and its high.

Stainless wire is prone to failure for a variety of reasons, which is one reason masts fall down. I cannot think of many who would consider it. Gal wire is an option it rusts quickly and the failure can be unseen within the wire.

Lifting wire is used in marine application but most times not in the same environment as a chain, sand, sea. mud. Chain last years - I don't think the same would be true of swaged wire. Wire is used for the anchor rode - I've seen it - but very uncommon.

Short scope

A Fortress anchor when well buried needs the same tension to lift it as was used to set it. Consequently the uplift load is the same as its hold. If you are patient you can break the anchor out - but sometimes a well set Fortress is simply irretrievable. So at a 'vertical' scope the hold and retrieval are similar. I have seen no data for other designs. Not for one moment would I suggest sitting with a vertical rode - we all carry enough rode to develop about 7:1, 8:1 the angle at which anchors are designed to set and set more deeply - for obvious reason we use that scope. In extremis you could use less (but I'd set an anchor watch).
 
Hurricane said:
+1 absolutely.
I don't think I could sleep at night knowing that the chain was pulling directly on the anchor.
It is so obvious to me.
All anchors work best if the pull is horizontally across the sea bed.
It doesn't matter if the argeument is that modern anchors still work when pulled at an angle.
They all work better if pulled horjzontally so why push the limits.
I like my sleep.
Click to expand...

Agree 100% H but apparently we're wrong:D
 
Neeves said:
Having gone through this debate in a previous thread, about the new anchor, I do indentify a different philosophy.

Mobo owners carry heavy chain and sometimes longer chain, because they can. 150m of 12mm has been quoted.

Yacht owners are more weight conscious and it would be most unusual for one to have 150m of chain and only someone with old fashioned ideas to carry chain of a link size larger than needed for the strength. Most would carry the link size recommended, for strength, and 100m max. Naby carry less than 100m of chain and will supplement with rope.

Yacht owners 'feel' restricted - the weight in the bow issue. Mobos can carry weight, or so they say, so they do not worry.

A Mobo with 150m of 12mm chain in 20m of water is a different animal oe the yachts of similar size with 12mm chain and 80m - in 20m of water.

Yacht owners who are to anchor where the ground tackle might be stressed MUST find other answers, than increasing weight or link and longer rode - the answer is very cheap and simple - snubbers

Mobo owners, who might, on commissioning, have a parsimonious chain, marginal link size and not much length simply throw money at the issue and buy more and more chain.

It is difficult to believe however that changing from 60m of 10mm chain to 150m of 12mm chain does not impact performance, it might be an acceptable difference but difficult to accept the difference is not there.

Because Mobo owners can simply add weight the concept of a smaller chain (but same strength of a bigger chain), which can be longer - offset that decrease in link weight with an increase in length - simply does not occur. The idea that a simple length of nylon can replace 50m of stainless has never been a concept of discussion. The idea that a snubber can replace catenary and and can be designed to work upto 70 knots, if you so wish, does not impinge on consiousness.

Smaller chain, same strength - offers the ability to use a smaller windlass, the windlass needs less deck reinforcing. The windlass will have a lower power draw, so smaller cables. The chain locker can be smaller, or possibly be better designed. The spare space freed up by using the smaller chain might be better used for something else. The down side is - you must use snubbers and they need to be about 30', or longer. For 70 knots you will need beefy snubbers - though Mobo owners, simply leave and go and find shelter elsewhere.

The limit of stronger chain is currently G100 - but its a bit pricey (not as much so as stainless) and realistically think G80.

But just because a 70' Mobo can carry 150m of 12mm chain does not mean its the best answer. Nor in fact might carrying 150m of 8mm HT chain be the best answer - but both options merit debate.
Click to expand...

You have made this a "yachtie/mobo" thing.
Where I'm berthed, I have a lot of yachtie friends who do the same as me.
48 foot sailing boats that carry 12mm chain isn't uncommon.

Also, as explained earlier, my 150m of chain is mainly so that I can anchor out and pull back to the rocks.
Usually, I rarely deploy much more than 40m - half of which would be on the bottom.
 
H,

I admit I'm taking the 2 extremes. To counter your yachtie friends with 12mm chain I can quote Dashew's customers who use G70 and snubbers.

Of course there are yachtie's who use 12mm chain (and cannot spell snubber) as equally there are Mobo owners who use, lightweight G70 chain and snubbers (and possibly think heavy chain is a waste). I'm quoting somewhere in the middle.

Its not a Mobo vs Yachtie thing its one philosophy in comparison with another - does not matter who uses it - they are both used by both.


Pulling back to rocks is hardly the confines of the Mobo owner - its standard practice for anyone in the Baltic - and where there is rock on the seabed they use dyneema tape on reels and most people carry 2 x 300' warps (sometimes on reels) to enable them to work in any location. The Balts have it down to a fine art - commonly with a bow roller (if that is not a contradiction) on the transom with anchor (as well as the more conventional on the bow). The dyneema tape (on reel) are commonly housed on the stern, sometimes one on each side.
 
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RupertW said:
It might be obvious but it's not true. In any wind that's noticeable you are always pulling directly on the anchor even when it's so light that lots of chain is resting on the sea floor. If you doubt this then try dropping the other end of the chain in an uncrowded anchorage in a couple of knots of winds and watch your boat going gently backwards no matter how much chain you pull out.
Click to expand...

there is no discussion about the fact that the chain is pulling the anker,
but my point is, when you have a lot of scope, there is at least some length of chain on the seabed, even at strong wind,
and then the force from the chain on the anker shaft is much more "smooth" and "damped by the friction of the chain with the seabed,

when anchoring in strong wind, (also in shallow water) we drop +60m....80m of chain, to be sure about a good hold,
and I am quite sure that in that case, there is "permanently" a length of chain on the seabed.
 
BartW said:
there is no discussion about the fact that the chain is pulling the anker,
but my point is, when you have a lot of scope, there is at least some length of chain on the seabed, even at strong wind,
and then the force from the chain on the anker shaft is much more "smooth" and "damped by the friction of the chain with the seabed,

when anchoring in strong wind, (also in shallow water) we drop +60m....80m of chain, to be sure about a good hold,
and I am quite sure that in that case, there is "permanently" a length of chain on the seabed.
Click to expand...

Agreed
 
Neeves said:
Its not a Mobo vs Yachtie thing its one philosophy in comparison with another - does not matter who uses it - they are both used by both.
Click to expand...

don't intend to go much deeper in to the M/Y debate,

but imo there is a big difference between anchoring a Y and a Mobo,

yachts have a keel, and most neighbour yachts I see, are smaller and lighter than our planing mobo,
the result is easy noticeable in a Anchorage at strong wind,
the yachts stay much more straight with the nose in the wind,
our mobo is much more swinging in the wind,
conider a huge tub floating on the water, not very deep draft, flat bottom at the stern, and no keel,
one side (big surface) catches some wind and is pushed to the other size, and then again the other side catches wind, puching the boat in the other direction.
at the moment when the wind is blowing full force at the huge surface / side of the boat, force on the anker is quite high, much higher than you will ever get in a medium sized y.
this phenomen is clearly noticeable with our boat, and a lot less or not at all with a sailing boat.
our swing is much bigger than sail boats, (its the swmbo who pointed this to me)
compareable size planing mobo's like mine, have the same swing
anyway this is not the kind of anchoring we fancy, and we avoid that whenever that is possible
 
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