G70 chain

[Yngmar]

Yngmar,

Thanks for filling in your usage. Couple of queries, why did you buy G7 in the first place and what did you have previously. I've looked at a number of samples of Maggi's A7, your chain will be marked as such, and the link size is very small, I could not use a 3/8th" shackle, the clevis was just too big. Your use of the swivel to attach to the chain implies an even small clevis -is it an oval shape to give the strength they specify?

edit another query - what sort of snubbers are you using? close edit

We upgraded the anchor significantly and went up a size over Rocnas recommendation (works brilliantly, although anchor roller needed modification and new nav lights). Previously had some 45m of 8mm unknown grade chain with intermittent rusty patches where it had lain in a puddle in the bottom of the anchor locker (now de-puddlified with rubber grass protector mats). Felt it was due for replacement and so might as well upgrade to a) longer (75m) and b) stronger chain, but 10mm would've meant a new gypsy (exceeding the price of the chain) and a massive amount of extra weight at that length, so going for 8mm G7 made a lot of sense.

The Kong swivel has a round forged pin that is part of one half of the thing and slots into a hole in the other half. Vyv has kindly published drawings, descriptions and load test results of these things (it's "J" on his list): https://coxengineering.sharepoint.com/Pages/Connectors.aspx

By the way, you can also get Maggi to ship the chain with oversized links on one or both ends of the same strength as the chain. Although the Kong swivel makes this unnecessary and we already had that.

The snubber I'm not happy with yet and will redo soon. It's a nylon octoplait 18mm with a stainless thimble spliced into an eye and a chain hook (this sort) shackled into it. I don't much like the arrangement - it's a bit too short, the hook has fallen off the chain once already in some swell and I'd much rather have a two-legged snubber going straight to the mooring cleats, as the current arrangement has to go through the anchor roller, which I don't like much. Putting the current one-legged snubber on either cleat makes the boat lay sideways to the chain, which can be useful but mostly isn't desirable, and the two-legged snubber can still do this. Have to do some research on how to make a better snubber myself.

 

[Neeves]

Thanks for the reply - lots of nice detail.

Many anchor lockers have the drain hole well above the locker base. If the locker base is above the waterline its worth drilling a new drain hole and adding a clam vent. I'm not sure what sort of 'mat' you have used but if you google 'gratings' you will find something really serviceable. Alternatives are the plastic gratings that are used in many marinas on their pontoons. Our locker base is flat and drains well but we have installed perforated rubber floor mats with dimples in the bottom - the chain drains well. The problem with leaving the puddle is that it evaporates, condenses higher up in the locker and then you have a constant stream of electrolyte running over the chain. Its better than the puddle but not perfect

Your snubber is too thick - think 12mm x at least 10m. The way to go is the bridle. its an easy fix.

Putting a gate on a cheap hook is easy, though a clevis hook is easier to adapt.

The oversized links sold by Maggi are expensive and monsters. People already complain about shackle pins sticking in the bow roller - the oversized link from Maggi will make anchor retrieval difficult.

Jonathan

 

[MM5AHO]

There's an article on snubbers, their need and how to arrange them on our website here.. http://www.knoxanchors.com/wind-forces-and-snubbing

 

[[2574]]

Maggi Aqua 7, 8mm connected to Rocna 20kg via Petersen D shackle:

and another

 

[Neeves]

Robih,

Very neat. I can see why you bought the Petersen, your bow roller channel is very narrow. A 3/8th" Crosby bow shackle has a 2t WLL and MBS of 9t and is cheap from Techni (and I assume others in the UK) - the downside is the protruding clevis pin. Its difficult to compare but it looks as if Maggi have got the message and found smaller Omega links.

What happens when the anchor comes up sideways, turned through 90 degrees?

Great fairleads! I love the little rollers, perfect for snubbers.

Jonathan

 

[[2574]]

Jonathan,

For reasons I cannot explain the anchor has always come up in the correct orientation. Maybe we're lucky but haven't felt the need for a swivel (which I have always avoided as surely it must add potential for failure due to its relative complexity compared to a shackle).

My only slight concern with my setup is the potential for a perpendicular pull from the chain on to the anchor which would place "unfair" sideways stress on to the Petersen shackle. That said the shackle has a WLL >2,000kgs which is well in excess of the Maggi WLL.

Yes, we like the fairleads though we can claim no credit for that - Nauticat standard design.

I have followed your comments apropos snubbers with interest. We deploy a 10m 12mm nylon octoplait snubber on a chain hook. It works well so far though I am concerned at the possibility of it falling off the chain if a surge caused the chain to go slack momentarily. That has not happened to us yet but I do sometimes think that I will upgrade to some kind of captive snubber attachment and also a longer, perhaps 20m snubber line. This would give better elasticity (about 6m of stretch). However I've yet to find a better snubber attachment device.

Rob

 

[Neeves]

You might find 2 snubbers, one on each side (same size) beneficial - you will effectively have a bridle which will reduce yawing. If you are running back to the transom then whatever your deck length, say 10m, allows you to have a 20m snubber with only 10m beyond the bow. If you can route to a sheet winch via a turning block, you can then control from the winch and not need to leave the comfort of the cockpit. The safety aspect was a bonus the real intent was to get as long as possible on the deck reducing the length forward of the bow.

Jonathan

 

[K-ron]

My issue with chain hooks is the fact that they can and will fall off the chain when anchored in shallow water if the length of the snubber from the bow exceeds the depth of water (and the wind drops off). The point of attachment on the chain hits the seabed and knocks the hook off. I appreciate this can be resolved by taking the bitter end of the snubber back to the cockpit and having a shorter length over the bow but it's not practical on my mono hull. Therefore I now use the olde trusted rolling hitch.

Kieran

 

[thinwater]

My issue with chain hooks is the fact that they can and will fall off the chain when anchored in shallow water if the length of the snubber from the bow exceeds the depth of water (and the wind drops off). The point of attachment on the chain hits the seabed and knocks the hook off. I appreciate this can be resolved by taking the bitter end of the snubber back to the cockpit and having a shorter length over the bow but it's not practical on my mono hull. Therefore I now use the olde trusted rolling hitch.

Kieran

a. A rolling hitch has been tested an show to slip at about 30% WLL. Many cruisers have experienced slipage and either double the hitch, use a camel hitch, soft shackle, or use hardware. "Olde trusted" is false security.

b. There are many locking hooks, as Neeves has stated. My personal favorite is illustrated below. This was an early prototype. The second hole is for attaching a second anchor rode. It can also easily be adapted to redundant snubbers. Very strong, can't come off.

c. I'm not sure why rigging the snubber back some distance is not practical. As a compromise, try the midships cleats--that is what I do. Unless the water is very shallow, that should be sufficient.

These are not the shackles I use--I was just staging a picture.


d. How strong does a snubber need to be? Clearly, it does not need to be sized for the vicious snatches that can take place when breaking an anchor loose. A separate, stout snubbing means is needed for that. Logically, the WLL of the snubber should exceed the maximum foreseen wind load, plus a safety factor of about 50-100% for waves. Thus, the breaking strength needs to be at least 8 times the maximum wind load (850 pounds for a 40-foot boat at 60 knot), or 6,800 pounds. ABYC, on the other hand, requires a BS of about 16,000 pounds for the ground tackle (WLL = 4,000 pounds). While this seems a lot weaker than the chain, a number of well-known cruisers have successfully sailed far using a single 11mm climbing rope for a snubber (~ 6,500 pounds BS), suggesting it is enough. Given that dragging has to be at least 100 times more common than breaking a chain or snubber, a softer snubber should help keep the hook in the bottom, which is what matters. Even if it fails, the chain is still secured to the boat with only a few meters of slack, and you can rig a back-up snubber if a sustained monster of a storm is expected. I use twin 8mm snubbers (34-foot cat, similar windage to 45-foot mono), with a combined BS of about 6,500 pounds, by the time allowance is made for angles and knots.

 

[Neeves]

One way to attach a snubber to a chain is a soft shackle, much favoured by Americans. You can read all about soft shackles on American forum where many will become quite ecstatic and emotional.

America chains, imperially sized, have a bigger orifice in the link than metric and I have not found a soft shackle both small enough and strong enough to fit metric chain. I have some 5/6mm soft shackles, they can be inserted into a 8mm chain - but I would not want to try it in the dark, rain and wind. Its a very tight fit - which defeats the object of the exercise - they are meant to be convenient.

Jonathan

 

[thinwater]

One way to attach a snubber to a chain is a soft shackle, much favoured by Americans. You can read all about soft shackles on American forum where many will become quite ecstatic and emotional.

America chains, imperially sized, have a bigger orifice in the link than metric and I have not found a soft shackle both small enough and strong enough to fit metric chain. I have some 5/6mm soft shackles, they can be inserted into a 8mm chain - but I would not want to try it in the dark, rain and wind. Its a very tight fit - which defeats the object of the exercise - they are meant to be convenient.

Jonathan

Another option I tested is to make a really long soft shackle and use it as a prusik sling. Works well. I sometimes use an ordinary sewn spectra climbing sling and attach it to the snubber or other rode with a carabiner, although this limits the strength to about 5000 pounds. A higher strength variation is possible. However, this is strong enough for boats up to about 40 feet. Again, the peak load should not exceed ~ 1000 pounds if the snubber is long enough.

There are many answers. You just need to pick the one that fits your boat. I use a locking Manus hook most of the time, just because it is super easy. It has also never failed, though the design works better in the 1/4-inch size than in larger sizes, where it becomes cumbersome. Again, it is a matter of choosing the solution that fits.

 

[GHA]

Soft shackle made from 5mm dyneema will, fit 10mm chain, mbl must be over 5t at least. Marlow d12 max is remarkably chafe resistant as well.

 

[Neeves]

Soft shackle made from 5mm dyneema will, fit 10mm chain, mbl must be over 5t at least. Marlow d12 max is remarkably chafe resistant as well.

Which soft shackle do you suggest for 6mm and 8mm G70?

What is the WLL of the metal connector between the soft shackle and snubber.

That 'snubber' will effectively take the full snatch load on the chain, its very short - if that is full length - and will offer no elasticity and will have no value for a G70 chain (where the chain has been downsized from 12mm) where the lighter chain has sacrificed much catenary.

Jonathan

 

[GHA]

Which soft shackle do you suggest for 6mm and 8mm G70?

What is the WLL of the metal connector between the soft shackle and snubber.

That 'snubber' will effectively take the full snatch load on the chain, its very short - if that is full length - and will offer no elasticity and will have no value for a G70 chain (where the chain has been downsized from 12mm) where the lighter chain has sacrificed much catenary.

Jonathan

Don't know about 8mm chain, sorry.

Stainless carbine hook doesn't have a wll, very few stainless rigging accessories do. But way above what it will be subject to in this situation.

And it's not a snubber, 2 anchors down Bahamian stylee posted to show soft shackles work just fine for 10mm chain, every boat should have some

 

[Neeves]

GHA,

I agree - soft shackles made from 5/6mm dyneema would be ideal for 10mm chain - but in terms of G70 there is more interest with owners using 10mm and 8mm G30 and looking to down size to 8mm and 6mm. I'm not sure why there is this pattern. It might be HT chain appeals to owners of lighter weight and weight sensitive yachts and they tend to be using smaller, not 12mm, chain in the first place.

Something to look at - make the soft shackle from 5/6mm dyneema with a dyneema cover and depending on the knot you can achieve over 200% strength of the base cordage. I have 2 here beside me to test. I'm told that people are using dyneema soft shackles (with a dyneema cover) as the shackle to join chain to anchor - I cannot confirm this practice. I think Thinwater is using dyneema as part of his 'second' rode - one major advantage being its light to deploy from a dinghy.

Soft shackles seem to be well below the horizon - your posting is unusual (and welcome). They are relatively easy to make at home, if you are handy with knots (and can be bought commercially - though I don't find commercial ones very cheap).

Sadly soft shackles for 8mm and 6mm are still something to strive for.

Jonathan

 

[noelex]

One way to attach a snubber to a chain is a soft shackle, much favoured by Americans. You can read all about soft shackles on American forum where many will become quite ecstatic and emotional.

America chains, imperially sized, have a bigger orifice in the link than metric and I have not found a soft shackle both small enough and strong enough to fit metric chain. I have some 5/6mm soft shackles, they can be inserted into a 8mm chain - but I would not want to try it in the dark, rain and wind. Its a very tight fit - which defeats the object of the exercise - they are meant to be convenient.

Jonathan

I have tried most of the chain /snubber connections and Dyneema soft shackles have been the best. They never come undone, are kind to the chain and its galvanising, never jam, are simple and quick to attach and finally, they are inexpensive (especially if make your own). There is a lot to like.

In terms of strength there should be no problems. The connection point does not have to be stronger than the chain, just stronger than the snubber.

A 4mm Dyneema soft shackle (which I think should easily fit through 8mm chain) made with SK75 should have a breaking strength of around 4600kg if you make it yourself using the latest recommended knots (my wife makes all ours). If you are really desperate for greater strength, you can use stronger grades of Dyneema (SK90 or 99), but this should be unnecessary even for those boats with G7 chain.

To put this in perspective, 14mm nylon (octoplait or 3 strand) has a breaking strength of 4100 kg and this is when dry and new. Nylon loses a lot of strength when wet (about 20%) and significantly more with age.

 

[Neeves]

Thanks Noelex,

But the thread had drifted off G70, slightly, and 'my' need is a for 'connectors' for 6m G100 galvanised to the strength of 10mm G30 (or 8mm G100 replacing 12mm G30).

The soft shackles I will be testing are SK99 core with SK78 covers giving a strength over 200% of the SK78 cordage being used - but they do not fit 6mm and 8mm link. Or they do fit 8mm - but you would not want to do it at 2am in the rain - too fiddly.

Snubbers need to be easy to attach, secure when attached and easy to take off - or they will not be used.

Useful though the thread drift might be it does not cover the concept of the thread which was people's usage of G70, experiences and would they use it again.

Jonatna

 

[thinwater]

Don't know about 8mm chain, sorry.

Stainless carbine hook doesn't have a wll, very few stainless rigging accessories do. But way above what it will be subject to in this situation.

And it's not a snubber, 2 anchors down Bahamian stylee posted to show soft shackles work just fine for 10mm chain, every boat should have some

a. There are stainless climbing carabiners that are load rated (WLL 1200-2500 pounds). Judging from the size (2 3/8"?) and style of this one, I'd be stunned if the WLL of that one was over a few hundred pounds pounds, which is not enough... but you may not have exceeded the BS and it has not fatigued yet. The designs of non-load rated carabiners are extremely variable and mostly useless. Basically a complete crap shoot. West Marine sells carabiners like the with WLL from 99-177 pounds.
https://www.westmarine.com/buy/west-marine--stainless-steel-carabiners--P002_060_002_002
https://www.westmarine.com/buy/suncor--stainless-steel-carabiners-without-eye--P002_060_002_500

b. One advantage of the soft shackle method is that you can recover it over the roller and make it up on-deck. Thus, the carabiner just makes for noisier recovery and is 100% not needed. Get rid of it. I have used soft shackles exactly as you show, but without the biner.

c. One way to make soft shackles easier to work with is to make them longer. Instructions are generally for tiny, short one you might use to attache a block. for something like this, there is no reason not to make it 4-8" long when closed. Much better.

 

[GHA]

a. There are stainless climbing carabiners that are load rated (WLL 1200-2500 pounds). Judging from the size (2 3/8"?) and style of this one, I'd be stunned if the WLL of that one was over a few hundred pounds pounds, which is not enough... but you may not have exceeded the BS and it has not fatigued yet. The designs of non-load rated carabiners are extremely variable and mostly useless. Basically a complete crap shoot. West Marine sells carabiners like the with WLL from 99-177 pounds.
https://www.westmarine.com/buy/west-marine--stainless-steel-carabiners--P002_060_002_002
https://www.westmarine.com/buy/suncor--stainless-steel-carabiners-without-eye--P002_060_002_500

b. One advantage of the soft shackle method is that you can recover it over the roller and make it up on-deck. Thus, the carabiner just makes for noisier recovery and is 100% not needed. Get rid of it. I have used soft shackles exactly as you show, but without the biner.

c. One way to make soft shackles easier to work with is to make them longer. Instructions are generally for tiny, short one you might use to attache a block. for something like this, there is no reason not to make it 4-8" long when closed. Much better.

A- This was just a first playaround & the crab was handy, I know it's not hugely strong and will be ditched next time but in this particular situation the factor of safety is huge with no big winds anytime soon. It's stamped at 8Kn max so swl of about 160Kg at 5:1 FOS if you believe the MBL. Another factor where some kind of eye or shackle would be beneficial is the bend radius of the rope rode around the soft shackle, there's a strong argument for something with a better radius at the connection point where the rope attaches to the soft shackle. I think Mk2 will be a longer soft shackle with a hard eye one end or maybe stay soft & choke the alpine butterfly and soft shackle together but something to get rid of that nasty radius.


Those links to west marine look like they are to items which aren't stamped, in Europe this means any WLL or SWL on a piece of paper but not stamped on the body doesn't really mean anything and wouldn't be legal, maybe different in the US
. For decades I worked in commercial rigging, there were no stamped stainless rigging accessories available way back, then maillon started selling tested maillon rapid 'quick links" - possibly after lots of requests from us lot in entertainment rigging as test certs for every piece of rigging became a must have.
Been a few years now since buying bags of them and a quick google comes up with a load of stamped stainless accessories available so things must have changed a bit.


PS - Sorry for thread drift, tis is the way the net is

 

[Neeves]

Thread drift is fully acceptable in my book. Especially on a thread on rodes and particularly on a thread on G70 - which is where newer ideas are being tested.

When you said earlier that stainless rigging was not stamped I did not like to argue (as I don't know about stainless rigging) but my 'biners' or as we angle saxons call them 'crabs' whether alloy (7075) or stainless are all stamped (and as Thinwater has said somewhere - they are all individually tested). Things have changed a lot with crabs since I bought them to use climbing and I lost touch, Thinwater put me back on the straight and narrow. The max strength I have found for climbing crabs is 27kn, recovery (?) crabs might be slightly higher. The most common crabs now seem to be alloy and come from China (with US or European brand names).

I have a small selection of alloy crabs with screw locks - I have not felt a pressing need yet to try or test them. In fact I'm not quite sure how to test them such that the test has nay validity or usefulness.

I think a few of us are playing around trying varying combinations - it will work itself out in time as to what is best.

But keep up the thread drift

Jonathan