djstefan
New Member
Does any one know where I can buy 8mm high tensile anchor chain in the uk?
High tensile anchor chain
- Thread starter djstefan
- Start date
TheBoatman
Well-Known Member
Poses the question ~ why would you want 8mm HT chain?
Peter.
Peter.
Adamastor
Well-Known Member
The stuff to ask for is Grade 3 galvanised chain. And if you're using it with a windlass, make sure it's calibrated chain- and calibrated to the correct standard- ISO or DIN. Before anyone asks, the 2-3mm difference in link-length WILL make a difference retrieving the anchor on a long scope. High Tensile chain won't be any good at handling shock-loading, and we have also had some dodgy situations raising questions about the wisdom of SS chain, or SS anywhere on the anchor-rode- you can't see if it's about to fail, without some serious metallurgical investigation, until it does!
Salty John
Well-Known Member
Jock89
Well-Known Member
Re' 8mm HT anchor chain...I'm also thinking along the same lines. My thinking is that I can probably get the breaking-strain of 10mm for the weight of 8mm. I can't quote any specifics here but over 60-70m I would think there'd be a substantial weight saving.?
I'd like to know more about this HT chain myself, & what's going to be ideal for my Nic-38. (+/- 9 tons, in cruising trim)
Jeff
I'd like to know more about this HT chain myself, & what's going to be ideal for my Nic-38. (+/- 9 tons, in cruising trim)
Jeff
Salty John
Well-Known Member
I've always used HT chain, actually US G4, for this reason. You can use a smaller gauge which, apart from being lighter is also more flexible and easier to handle.
G3 chain 7/16" gauge has a WLL of 3500 lbs whereas 5/16" G4 has a WLL of 3900 lbs. The weight difference is 217 lbs per 100' versus 110 lbs per 100'. This is a substantial weight saving when you carry two 150' all chain rodes. I'm sure the same sort of weight saving is available between UK Grade 30 and Grade 40, but I haven't used UK chain personally.
G3 chain 7/16" gauge has a WLL of 3500 lbs whereas 5/16" G4 has a WLL of 3900 lbs. The weight difference is 217 lbs per 100' versus 110 lbs per 100'. This is a substantial weight saving when you carry two 150' all chain rodes. I'm sure the same sort of weight saving is available between UK Grade 30 and Grade 40, but I haven't used UK chain personally.
vyv_cox
Well-Known Member
Grade 40 chain has a UTS about 1.5 times that of normal Grade 30 chain. There is also a Grade 70 that is almost twice the strength of Grade 30, although hot dip galvanising reduces this by 10%. Advice seems to be that users of the Grade 70 can reduce chain size by one, e.g. from 8 mm to 6 mm, or 10 mm to 8 mm.
In theory the extra strength is achieved at the expense of ductility but IMHO this is unlikely to be an issue in anchoring.
As has been said above, you may need to change the gypsy in your windlass to suit the slightly longer link length.
In theory the extra strength is achieved at the expense of ductility but IMHO this is unlikely to be an issue in anchoring.
As has been said above, you may need to change the gypsy in your windlass to suit the slightly longer link length.
Bilgediver
Well-Known Member
If you want HT it is Grade 40.
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It most certainly is not.....Grade 40 is Bog standard.
Please read the catalogue for the high grade.
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It most certainly is not.....Grade 40 is Bog standard.
Please read the catalogue for the high grade.
Trundlebug
Well-Known Member
Bear in mind the extra weight of heavier chain is actually an advantage when the anchor is in use, because of the suspension curve creating a shock absorber effect, and even reducing the strain on the anchor. It will also reduce swing and aid stability.
Just thought it was worth mentioning, don't only consider the weight of chain when you're stowing it. Unless the boat is semi displacement or planing, storage weight should not be an issue, unless the problem is hoisting it all back in. In which case - get a bigger (electric) windlass!? /forums/images/graemlins/grin.gif
Just thought it was worth mentioning, don't only consider the weight of chain when you're stowing it. Unless the boat is semi displacement or planing, storage weight should not be an issue, unless the problem is hoisting it all back in. In which case - get a bigger (electric) windlass!? /forums/images/graemlins/grin.gif
Speed
Active Member
I have spent much time this winter trying to track down a supply of G70 chain in the UK, and drawn a blank . ACCO G70 is widely available in the US, via WEST Marine, for example, but the cost of getting it over is prohibitive - so if anyone has any idea where to track down Lofrans calibrated G70 in the UK or Europe, please put me out of my misery!
Totally agree with your comments re chain in the separate thread. We would like to carry more, but avoid the weight penalty if possible, hence the search for G70. Lying to chain you range around far less, and with a chain hook(s) and a good length of nylon, can stop it snubbing. Much better!
Totally agree with your comments re chain in the separate thread. We would like to carry more, but avoid the weight penalty if possible, hence the search for G70. Lying to chain you range around far less, and with a chain hook(s) and a good length of nylon, can stop it snubbing. Much better!
vyv_cox
Well-Known Member
<<<<<because of the suspension curve creating a shock absorber effect >>>>>
There is a great deal of mathematical evidence that shows this only to be true up to about force 7, dependent upon various factors. Above that wind strength the chain is straight and effectively acts as a bar, transmitting wave shock loads to the anchor, where it will lift the stock and either trip the anchor or cause it to drag. Replacing much of the chain with nylon rope will help to prevent this from happening. Use of an Angel is shown to barely improve the situation.
An option used by many to keep an all-chain rode but to introduce elasticity is to use a nylon snubber in parallel with the chain. This needs to be several metres in length to be effective. I deliberately use only 12 mm nylon for this, usually about 5 metres long. It visibly stretches under load.
There is a great deal of mathematical evidence that shows this only to be true up to about force 7, dependent upon various factors. Above that wind strength the chain is straight and effectively acts as a bar, transmitting wave shock loads to the anchor, where it will lift the stock and either trip the anchor or cause it to drag. Replacing much of the chain with nylon rope will help to prevent this from happening. Use of an Angel is shown to barely improve the situation.
An option used by many to keep an all-chain rode but to introduce elasticity is to use a nylon snubber in parallel with the chain. This needs to be several metres in length to be effective. I deliberately use only 12 mm nylon for this, usually about 5 metres long. It visibly stretches under load.
craigsmith
Well-Known Member
The OP has sensibly asked re high tensile chain and has received mostly misleading and misinformed responses.
HT means high tensile. That a few chandleries make the common mistake of confusing it with hi-test, the popular American marketing term for G40 (vs BBB/G30), does NOT make it the same.
High tensile chain is typically G70. There are a handful of reputable makes who do galvanized versions.
Weight is NOT critically important in an anchor rode, and selecting G70 chain of equivalence in terms of strength to what one would normally choose in G40 is emminently sensible. It saves a large amount of weight, a bit of which may if desired be put back into a larger anchor, for a far better performing system at a total mass in the bow still lower than otherwise.
The disadvantage is cost, although on a strength-for-strength basis the difference is not huge, plus the issue of switching windlass wildcats if it's an upgrade. You also shouldn't re-galvanize HT chain, but then many decide it isn't economical to re-galvanize even G30/40, so that may or may not be an issue.
To compensate for high tensile's hardness, it should be spec'ed slightly stronger than G40 would be.
Sorry I can't help re availability in the UK. While ACCO is the US brand, Maggi in Italy do the stuff, and that's probably more common throughout the rest of the EU. I'd suggest you look for resellers of Maggi hardware, and enquire with them even if they don't advertise their G70 (they sell it as "transport chain").
www.rocna.com/boat-anchors/catenary.php
HT means high tensile. That a few chandleries make the common mistake of confusing it with hi-test, the popular American marketing term for G40 (vs BBB/G30), does NOT make it the same.
High tensile chain is typically G70. There are a handful of reputable makes who do galvanized versions.
Weight is NOT critically important in an anchor rode, and selecting G70 chain of equivalence in terms of strength to what one would normally choose in G40 is emminently sensible. It saves a large amount of weight, a bit of which may if desired be put back into a larger anchor, for a far better performing system at a total mass in the bow still lower than otherwise.
The disadvantage is cost, although on a strength-for-strength basis the difference is not huge, plus the issue of switching windlass wildcats if it's an upgrade. You also shouldn't re-galvanize HT chain, but then many decide it isn't economical to re-galvanize even G30/40, so that may or may not be an issue.
To compensate for high tensile's hardness, it should be spec'ed slightly stronger than G40 would be.
Sorry I can't help re availability in the UK. While ACCO is the US brand, Maggi in Italy do the stuff, and that's probably more common throughout the rest of the EU. I'd suggest you look for resellers of Maggi hardware, and enquire with them even if they don't advertise their G70 (they sell it as "transport chain").
www.rocna.com/boat-anchors/catenary.php
captainslarty
N/A
or, just go for decent ss 10 mm
djstefan
New Member
Dear all,
Thanks for your comments all of which I read with interest - my plan is to drop from 10mm standard to 8mm high tensile chain allowing me to carry more chain without additional weight in the bow or impact on strength.
The down side seems to be cost and a lower tollerance to shock loads - but of course this can negated with a good snubber adjusted according to the conditions (longer to allow more stretch as loads increase). All I need to do now is find some.....
Thanks for your comments all of which I read with interest - my plan is to drop from 10mm standard to 8mm high tensile chain allowing me to carry more chain without additional weight in the bow or impact on strength.
The down side seems to be cost and a lower tollerance to shock loads - but of course this can negated with a good snubber adjusted according to the conditions (longer to allow more stretch as loads increase). All I need to do now is find some.....
MM5AHO
Well-Known Member
Hydrogen embrittlement of the HT chain steel is a real problem in hot dip galvanizing.
Cannot recommend galvanizing HT chain for anchor applications.
Cannot recommend galvanizing HT chain for anchor applications.
rogerthebodger
Well-Known Member
If you take a HT chain ,which is hardened and tempered to give high strength but results in a less ductile chain and galvanise it the resultante chain is further tempered but the heating and cooling during the galvanising process. The degree of tempering depends on the temperature of the zinc bath used.
If you looh at the Bradney chain web site you will see the grade 80 chain is available and is much stronger the grade 40 but is not available in galvanised, olny up to grade 40 is available. This is because the grade looses strength guring the galvanising process.
Sime one quoted a 10% loss but this very much depends on the temperature as said above.
In general the higher the galvanising temperature the thinner the coating so galvanising tend to use a higher temperature to the usage of zinc which is a major cost in the process.
Be careful of buying so called galvanised HT chain as it may start as HT but will not be after galvanising.
If you looh at the Bradney chain web site you will see the grade 80 chain is available and is much stronger the grade 40 but is not available in galvanised, olny up to grade 40 is available. This is because the grade looses strength guring the galvanising process.
Sime one quoted a 10% loss but this very much depends on the temperature as said above.
In general the higher the galvanising temperature the thinner the coating so galvanising tend to use a higher temperature to the usage of zinc which is a major cost in the process.
Be careful of buying so called galvanised HT chain as it may start as HT but will not be after galvanising.
MM5AHO
Well-Known Member
Its not the temperature of the zinc in galvanizing thats a problem with HT chain, its the hydrogen embrittlement that can be brought about by cleaning the steel in acid.
Grade 80 chain should not be galvanized. Grades 30, 40 are OK, and in fact are used in many galvanizing plants to suspend heavier materials in the acid, and later the zinc during processing. Grade 80 is never used.
Its not strictly correct to say that the higher the temp the thinner the coating. In most cases the higher the temperature, the thicker the coating due to the higher rate of alloying reaction.
Thisckness of galvanizing is controlled by several factors.
Immersion time: and the thicker the cross section, the longer it will take to equal the zinc temp, so thicker steel gets thicker coatings.
Termperature: In general the higher the temp the thicker the coating.
Steel chemistry: Silicon and Phosphorous content influences the reaction between iron and zinc greatly. This can double or trebel the thickness of the coating, which might be a good or a bad thing.
Surface profile: Shotblasting the surface to say standard SA 2 1/2, (re-profiling it) will typically double the coating thickness.
Galvanizing grade 80 chain is not just a matter of downgrading its rating to the equivalent of grade 40 etc. Its far more serious than that. There's a high risk of catastophic failure. Embrittlement can cause total failure.
Grade 80 chain should not be galvanized. Grades 30, 40 are OK, and in fact are used in many galvanizing plants to suspend heavier materials in the acid, and later the zinc during processing. Grade 80 is never used.
Its not strictly correct to say that the higher the temp the thinner the coating. In most cases the higher the temperature, the thicker the coating due to the higher rate of alloying reaction.
Thisckness of galvanizing is controlled by several factors.
Immersion time: and the thicker the cross section, the longer it will take to equal the zinc temp, so thicker steel gets thicker coatings.
Termperature: In general the higher the temp the thicker the coating.
Steel chemistry: Silicon and Phosphorous content influences the reaction between iron and zinc greatly. This can double or trebel the thickness of the coating, which might be a good or a bad thing.
Surface profile: Shotblasting the surface to say standard SA 2 1/2, (re-profiling it) will typically double the coating thickness.
Galvanizing grade 80 chain is not just a matter of downgrading its rating to the equivalent of grade 40 etc. Its far more serious than that. There's a high risk of catastophic failure. Embrittlement can cause total failure.
rogerthebodger
Well-Known Member
Must admit my chain / galvanising experience was 25 odd years ago when I worked designing crane and chain hoists when I used to visit Bradley chains 5 miles from where I lived
gianenrico
Well-Known Member
The peace of mind of having 75 meters of G70 8mm chain under 45 kts of wind in an anchorage INSTEAD of 50 meters is, IMHO, noticeable.
Boat is a 7.5 tons 40 footer.
Under such conditions radius of swaying is usually not critical.
The chian will act as a catenary and thus absorb the shocks; a snubber is anyway a good add-on.
Just a satisfied italian ( /forums/images/graemlins/wink.gif Maggi's client.
Cheers
Boat is a 7.5 tons 40 footer.
Under such conditions radius of swaying is usually not critical.
The chian will act as a catenary and thus absorb the shocks; a snubber is anyway a good add-on.
Just a satisfied italian ( /forums/images/graemlins/wink.gif Maggi's client.
Cheers
