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#11 Chrisc

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Posted 20 June 2019 - 06:26 AM

looks like a home made POS to me!


I've only just twigged as to what POS means, or rather what I hope it doesn't mean.
My opinion is that when you see the same bit of gear on a lot of different boats it's because it's a proven piece of equipment and well suited to its purpose. This is the case with my POS which is identical To everybody else's POS, differing only in size. They are found on private boats from around 8 - 9 meters all the way up to the 80 meter commercial vessels so obviously suitable for canals and rivers.
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#12 Island Time

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Posted 20 June 2019 - 08:11 AM

Ha Chris, probably fine for that, I have virtually zero experience of anchoring in rivers and canals!


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#13 Knot Me... maybe

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Posted 20 June 2019 - 08:47 AM

Interesting about the Euro versus Chinese chain KM.
The 8 mm short link chain offered at €5.80/metre, assuming I can get my hands on it, is made in France, Grade 40, ISO 4565, whatever all that means.

Interesting. There are many selling chains whose total knowledge comes from the person selling them. We have one popped up here recently selling the chain as 'European' as that's what the winch mob he buys it off told him. But who he buys it off doesn't make chain and it's very obviously Chinese. He knows it too, the cheeky prick..anyway..

 

That could be EU made as I mentioned yesterday but it'll probably be Italian. France is good on BIG gear but not a player in small, Italy is the opposite so a good pairing. There is a fair bit of EU made stuff which gets regarded as 'local' due to all the tie in.

 

ISO4565 is a ISO standard which for the average boater is simply a 'physical size'. In 8mm ISO4565 and DIN766/A, the other common ISO standard, measure the same physical size.

 

Grade 40 for the average boater is 'strength'. The most common grade found is Grade 30 but more and more Grade 40 is being seen. Other grades available, if you know where to shop, is Grade 50 but that's rare and pretty much out of Aussie only and then there is hell strong Maggi AQUA7 a Grade 70, it's the strongest open link galvanised chain around.

 

8mm -

Grade 30 - bust 3200kg - note here many Chinese made chains claiming to be G30 will never make that load, many are only G20

Grade 40 - bust 4000kg

Grade 70 - bust 7000kg - note here, 95% of boats that 'need this' don't.

 

Buy that one you are talking about, it'll work for you very well.

 

Pool type anchors are very common in the UK due to so much soft bottom, easy and cheap to make so cheap to buy. I'd think the canal share similar bottoms and if you only need a 'just in case' a pool would be a good option. It's sort of the EU's version of a Danforth.

 

NZ doesn't see quite a few anchors for assorted reasons, a big one being we don't tolerate crap well as we do anchor in oceans and tend to have a more 'go hard or go home' approach to boating than most. I had some Swedish people out a few months ago and they were gobsmacked to see Optis sailing in 25-30kts, to them that was head for the storm cellar stuff. So a lot of the, generally fringe, anchors we don't see (even if we do stock and sell a lot of small Pools general into commercial)  but NZ and Aussie to tend to be leaders in serious anchors with the Sarca, Supreme, Excel plus input in to a few Chinese made ones like Rocna and Kewene.

 

That anchor, a length of 8mm chain and some 14mm string behind it, set it well and I'll sleep happily aboard the good ship C&J, in liue of knowing her real name.


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#14 Knot Me... maybe

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Posted 20 June 2019 - 10:52 AM

ISO4565 is a ISO standard which for the average boater is simply a 'physical size'. In 8mm ISO4565 and DIN766/A, the other common ISO standard, measure the same physical size.

We've just had another boater in with winch issues. As it pans out he was sold the wrong Standard chain as the mob doing it get their product knowledge from China and they all think ISO4565 and DIN766/A are the same. So I thought I just better clarify that bit above.

 

Those 2 standards are the same physical measurements in 6 and 8mm chains ONLY.

In all other sizes they vary, especially 10mm. Most winch gypsies will run one or the other, very very very few will run both.


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#15 Chrisc

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Posted 20 June 2019 - 07:38 PM

Thanks to KM for a detailed description of the ins and outs of anchor chain. I have found a source of the 8mm grade 40 chain where we are here in Toul, cost €7 per meter, a bit more than the other guy but then I don't have to pay for delivery.
I'm reluctant to buy 10m of it.
I started this post querying whether I could get away with less than 10m of chain in my rode. There are two reasons for this. Firstly, here's a picture of the foredeck.Attached File  20190620_084729.jpg   773.52KB   0 downloads
As you can see its not exactly well set up for handling an anchor. The only place I can see to stow an anchor rode is in a plastic bin on the foredeck.
Secondly, everybody knows that in a chain/rope rode the chain should equal the length of the boat. Well, why? What is the correlation between chain length and boat length? So if you have a 15m super slippery ultra lightweight low volume low windage race yacht you need 15m of chain in your rode. Yet I with my 10m high wooded heavy bluff bowed dumpy putterboat only need 10m of chain. So how does that make any sense?
So, kicking all the 'everybody knows' sacred cows, here's another one. Whilst chain does of course provide protection against chafe from the sea bottom and it limits sheering, I do not believe that it does much to improve holding. I have been anchored twice on all chain in well over 60 knots of sustained breeze (in a yacht, not the putterboat). This is the sort of stuff that when you go forward to check your gear you crawl on your hands and knees - the wind is too strong to stand up in. in these conditions I note that the chain leaves the fair lead and enters the sea about 15m ahead of the boat and the chain is bar tight and dead straight. Not an inch of cantenary in it at all. So the chain will provide cantenary and thereby give a horizontal pull on the anchor in benign conditions, when you don't need it. And in severe conditions when you do need it, you don't get it. My opinion is that 8 and 10mm chain used by the average boater is too light to provide any useful benefit in terms of holding, exceptions in regard to chafe and sheering as noted above.
And that is why I am reluctant to fork our dollars and give myself storage problems when anchoring in canals may be regarded as anchoring in a puddle in a paddock. This is not the Hauraki Gulf.
Right, now I'll tie myself to the stake for my heretical comments on chain. Roll up with the matches.
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#16 Dtwo

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Posted 20 June 2019 - 07:46 PM

If the chain is bar-tight, surely the effects of gravity are working exactly the same way and the catenary force is still active - it still wants to pull the chain down?


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#17 Chrisc

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Posted 20 June 2019 - 07:57 PM

Of course in these conditions it is not possible to see the anchor stock but by implication if the chain is bar tight then the anchor stock is in line with the chain and not lying on the sea bed as it should be.
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#18 Chrisc

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Posted 20 June 2019 - 08:04 PM

Right, now we are off to collect the chain. I don't necessarily agree with the purchase for the reasons stated above but if your wife tell you to buy chain, then you buy chain. (Sigh)
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#19 Island Time

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Posted 20 June 2019 - 08:57 PM

If that is the case Chris, the anchor will pull out. Once the angle is towards the surface, it relies purely on the shear strength and weight of the seabed material. Its essential that the pull is along the seabed to retain holding power. Hence, more scope for better holding. With a long scope, it does not take a huge weight to deflect the rode sufficiently to keep the angle of pull parallel to the seabed.

In your experience above, even when the chain looks bar tight and straight, it is almost certainly NOT going directly to the anchor, or it would not stay put...

IMO. Knot me would likely have more to say... 


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#20 Chrisc

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Posted 21 June 2019 - 12:49 AM

If that is the case Chris, the anchor will pull out.


I don't think it would. At a 10 : 1 scope in heavy conditions and assuming the anchor rode bar tight and the stock of the anchor in line with the rode then the angle of the anchor stock with the seabed would be 6°. If the flukes of the anchor rotate 30° either side of the stock which I think would be about that without actually measuring, then the anchor would still dig in.
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