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Old 10-03-2014, 18:24   #31
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Re: Anchor

I've got a 105 lb. CQR on 350' of 1/2" chain on the bow, plus a 70 lb. Danforth on a 25' 1/2" chain plus rode on the stern, and neither has dragged to date. ;-)
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Old 10-03-2014, 18:26   #32
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Re: Anchor

In regard to the Rocna and anchor testing, there are about 100 threads already started and quite extensive on this forum in regard to that specific subject. It has little bearing on the OP's question of whether a 25 kilo Delta will work for his 46' catamaran. If possible, can we all keep this thread slightly on this subject.
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Old 10-03-2014, 18:28   #33
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Re: Anchor

Hi Andrew,

In my searching for meaningful test results (and I agree with the point of your post re test parameters vs real life situations) I found this article by a multihuller in Australia who seems to take testing quite seriously. I thought it contained some valuable information and testing took into consideration some real world scenarios such as degree of horizontal pull, shift of pull direction, mud fouling flukes when re-setting etc.

I'd be interested in your take on it.

http://www.mysailing.com.au/news/tes...ion-of-anchors
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Old 10-03-2014, 19:00   #34
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Re: Anchor

I think I understand Palarran's request, but I don't entirely agree.

This is a discussion forum, and (particularly once the OP's question has been addressed, which seems to me the case here) the discussion will inevitably range further.

Anchor testing seems to offer a way to rise above an often fruitless contest between the preferences and experiences of often strong-minded individuals, whose requirements and circumstances differ widely.

And so, not surprisingly, tests were mentioned. To leave tests un-discussed, as if this were a purist Q&A medium, risks leaving the impression that tests are not controversial in their applicability.

And the thoughts I jotted down had not hitherto occurred to me in a coherent form, so it seemed like an opportunity to share them.

It seems to me that if the OP has no wider interest in the 'workings' beyond his narrow question, he has only to skim the thread to pick out those who are brave enough to give a specific 'answer'.
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Old 10-03-2014, 19:23   #35
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Re: Anchor

Fair comments all 'round, including both Andrew Troup & Palarran, at least in our view.

...and thanks, Andrew, for your considerable and detailed remarks about anchor testing in general. We agree completely...and in fact we observe similar deficiencies in the standardized testing of solar panels which typically involve assumptions that bear little resemblance to actual use, e.g. direct and clear overhead sunlight and laboratory-controlled temperatures...and even less resemblance to the use of solar panels on vessels! Anyway, that's a HUGE thread drift so we'd better no go any further there!!

Back to anchors and now chirping our bit in relation to anchor testing, we tend to assign quite a bit of weight (no pun intended! ) to the Lloyd's ratings. No doubt there'd be at least a few here who've observed insurance companies at work...and our similar observations over many years suggests that if an insurer publicly rates an anchor as 'High Holding Power', thus encouraging its customers to rely on that anchor, you can be fairly confident that rating is firmly grounded -- There we go again... -- in claims experience...and that's very relevant to real world sailors!
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Old 10-03-2014, 19:34   #36
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Re: Anchor

sounds pretty good to me. I used a Delta next size down on my 42 cat throughout the caribe. (44 lb?)
BTW, here's an interesting take. In the Tobago keys, with a steady 32 wind and gust to 40 for hours (Flat water in the anchorage as no fetch) I snorkeled the anchor and chain. Guess what? The chain still had catenary to it and there was no apparent tightening of the chain.
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Old 10-03-2014, 19:36   #37
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Re: Anchor

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Originally Posted by Andrew Troup View Post
I'd be interested to know the respective weights of the two anchors, and whether you've found a pattern to the types of bottom each prefers?

TIA
35 pound Manson and 33 pound Bruce. Still trying to figure out the pattern, but I am trying to figure out a lot of things about boats and sailing.
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Old 10-03-2014, 20:41   #38
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Re: Anchor

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I'm really enjoying following this thread. it's very educational... I have 2 questions:

(a) how is it physically possible that a 25KG (approx 55lb) anchor can hold a 15+ ton vessel.. such as the Lagoon 450??!?!?! seriously?! it just boggles the mind how something so tiny can anchor something sooo big!


SNIP
The anchor is only one part of the ground tackle used to hold a boat. It is not uncommon for the chain to weigh a couple of times more than the anchor. It is even possible for the rope to weigh as much as the anchor.

But even a good anchor and chain can drag if it is not set well or if the spot chosen to anchor is not selected well. The breaks on a car may only weigh 20 pounds but they keep a 5k pound car from moving.

Just a quick word about anchor testing. Selecting the right spot to anchor and setting it right with a reasonable amount of chain will be more important than using a Manson or a Bruce (or the brand you like best).
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Old 10-03-2014, 20:47   #39
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Re: Anchor

Andrew that is a great and thoughtful review of anchor tests.

I agree with most of your sentiments of the limitations. I would further add that even the large reports have a reasonably small number pulls in only a few bottom types. We really need to read many anchor tests and develop a weighted (based on the quality of the test) mean.

Having said that my assessment of different anchor designs (which is based mostly on my observations in the real world ) agrees surprisingly closely with the independent anchor tests (when they are considered as a whole). Based on the performance with a constant direction of pull. (Which is generally all the tests try to measure)

I think the results of the better anchor tests should be read with some caution, but they should still be given some consideration, observing some of the cautions Andrew has outlined.
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Old 10-03-2014, 21:02   #40
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Re: Anchor

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Selecting the right spot to anchor and setting it right with a reasonable amount of chain will be more important than using a Manson or a Bruce (or the brand you like best).
Hear! Hear!!
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Old 10-03-2014, 21:10   #41
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Re: Anchor

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Originally Posted by Cheechako View Post
sounds pretty good to me. I used a Delta next size down on my 42 cat throughout the caribe. (44 lb?)
BTW, here's an interesting take. In the Tobago keys, with a steady 32 wind and gust to 40 for hours (Flat water in the anchorage as no fetch) I snorkeled the anchor and chain. Guess what? The chain still had catenary to it and there was no apparent tightening of the chain.
Been there, done that. Just my two cents but the best way to learn about anchors is to dive on them. In the keys I dive almost every time I set the anchor. Also try and do it on some what of a regular basis if I am at an anchorage for any length of time.

I tend to drop the anchor and let out say 15 feet of chain in 10 feet of water and see how the anchor grabs. Once it gets a little tension on the chain I let out maybe 10 feet of chain and repeat the process till I have about a 7:1 ration of rode to depth. Funny thing is that if I dive the anchor a couple of days later the chain has often caught on rocks or other stuff on the bottom so it is not in a straight line, rather like two straight lines.

I suspect letting out 100feet of chain in 10 feet of water would let just about any reasonable anchor hold in lots of conditions.
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Old 10-03-2014, 21:58   #42
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Re: Anchor

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Originally Posted by noelex 77 View Post
Andrew that is a great and thoughtful review of anchor tests.

I agree with most of your sentiments of the limitations. I would further add that even the large reports have a reasonably small number pulls in only a few bottom types. We really need to read many anchor tests and develop a weighted (based on the quality of the test) mean.

Having said that my assessment of different anchor designs (which is based mostly on my observations in the real world ) agrees surprisingly closely with the independent anchor tests (when they are considered as a whole). Based on the performance with a constant direction of pull. (Which is generally all the tests try to measure)
.....
Thanks N77, I take a lot of notice of your thoughts on anchoring topics, so perhaps I was onto something.

One other point: the prevailing "light chain" movement, started by a person with a preference for massively heavy anchors, has received the imprimatur from several other key thinkers and opinion shapers, and become the de facto standard for cruising vessels.

NewGen anchors are (it seems to me, whether intentionally or adventitiously) designed to suit light chain.

I find the theory quite unconvincing, because it relies on static force analysis, rather than dealing with the dynamic energetics of the way the forces acting on the boat are applied to the anchor, which would require looking at the first and second derivatives of the relationships between tension and direction.

So I'm never going to be able to talk anybody round to my point of view, any more than a rocket scientist would be able to convince us what did or did not tally with the realities of orbital dynamics in the opening scenes of "Gravity".

Why I bring this up, when the battle for new hearts and minds seems irretrievably lost, is this:

In respect of "Old Gen" anchors, this may in some cases put them at an artificial disadvantage, even if anchor testing were made more realistic, because it's my feeling, supported by dynamic analysis, that chain size and weight is a major factor in keeping some of them from dragging. The ethos of "putting all the weight in the anchor, and as little as possible in the chain" is not, I think, equally applicable to all anchors and bottom types.

And the tests invariably (and inevitably) use the same chain -- if they use chain at all -- for all anchor designs. And, of course, it's "light" chain, in comparison with what the earlier designs tend to require to perform as intended.

And perhaps anchor effectiveness observations based on the success of others need to be tempered with an assessment, not just of whether their chain is suitably massive, but whether their technique is well adapted to their anchor --

otherwise it would not be surprising if the real-world observations appeared to support the results of the tests, because in both cases, the same 'knee-capping' of potential could conceivably be happening. Or not
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Old 11-03-2014, 00:55   #43
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Re: Anchor

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Originally Posted by BigBeakie View Post
Hi Andrew,

In my searching for meaningful test results (and I agree with the point of your post re test parameters vs real life situations) I found this article by a multihuller in Australia who seems to take testing quite seriously. I thought it contained some valuable information and testing took into consideration some real world scenarios such as degree of horizontal pull, shift of pull direction, mud fouling flukes when re-setting etc.

I'd be interested in your take on it.

Testing the new generation of anchors
@BigBeakie

Thanks a lot for that link.

It'll take me a while to digest it, but here's my off the cuff reaction:

I personally have long thought Jon Neaves (who is respected contributor here) to be head and shoulders ahead of most nautical journos in trying to address these questions, and I see from that recent write-up that he's continuing to make effective strides in the direction of real-world relevance.

But I think there will always realistically remain a gulf between what is practicable and affordable in testing, and what is encountered in practice, particularly with regard to difficult bottoms.

Evans Starzinger and a friend tried to bridge this gulf some years ago in a test they undertook with respect to just one particular type of difficult bottom (bouldery rocks) but inevitably the results had a lot of "noise" relative to the signal, and testing methods were very hard to verify for repeatability, let alone standardise for others to be able to independently replicate and build upon.

The question of the boat sawing sideways and ranging fore and aft is also too expensive to be simulated in any repeatable way, and in any case, different anchors will have different vulnerabilities in terms of these aspects of load regime.

Jon has tried to nod in the direction of that question, it seems, by a single pull at ninety degrees, and another at 180. This is useful info, but does not illuminate, say, the vulnerability of an anchor to being progressively "walked out" by repeated and reversing minor angular variations of maybe 10 degrees in the horizontal plane. This is more troubling, because (unlike the major wind-shift) whoever is onboard is unlikely to sit up and pay particular attention to a steady-state vulnerability.

He notes that snatch loading is not something which he can realistically test, and I note that some of his tests (as usual, even by anchor designers) appear to have been done on the beach, and others presumably in the intertidal zone, and even there (in my experience) the bottom condition and characteristics are never comparable with the zone where it is continuously submerged, where real-world anchors almost always are laid.

I also find his selection of a bungy jump analogy for a snubber unfortunate, but perhaps it arises from his multihull focus. The distinction I would draw is fairly involved, so I won't launch into it here.

In theory, the www offers a perfect opportunity to crowd-source real-world data, but there is minimal accountability, a massive amount of noise vs signal, and this time, some of the noise arises from 'human factors'.

I think that it may always be the case that testing anchors in order to find the "one to rule them all" is a bit like generic testing for the perfect husband or wife. Firstly, there is no such thing, and secondly: the answer depends entirely on who is asking.
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Old 11-03-2014, 02:02   #44
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Re: Anchor

Please do not turn this in to another anchor type comparison thread just because I posted a link to a particular vendor. I only posted the link to the Rocna site so another poster could get a visual idea of how an anchor works. If anyone is interested in arguing about the different types of anchors, I suggest they re-open one of the existing threads where this has been done to death.
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Old 11-03-2014, 05:08   #45
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Re: Anchor

I forgot to include a couple of links to current anchoring threads in my previous post:

Anchors - Bigger is Better ?
Do I need a new gen anchor?
What Size Anchor
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