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Old 24-02-2014, 01:56   #31
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Re: Do I need a new gen anchor?

Quote:
Originally Posted by nigel1 View Post
I'm a firm believer in not keeping the chain between anchor and windlass bar tight. The reason being that the constant tension on the windlass is no good for bearings and bushes. Instead, once I have the anchor on the roller, I use a length of dyneema between anchor and a cleat to keep the anchor secure on the roller. Looking at adding something a senhouse slip in the setup to allow for quick release.
+1

We use a claw chain hook on the rode attached to a strong point and leave the chain to the windlass slack. We have used a stainless rod through holes in the roller and through a link - but this can be fiddly (at night) - but would use it for long or rough passages.

There are number of ways to stop the anchor 'swinging' the simplest is lashing it - to something. We use a home made nylon wedge, well 2 wedges, between bow roller plates.

Jonathan
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Old 24-02-2014, 02:14   #32
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Re: Do I need a new gen anchor?

I have a photo I took of the top 10m or so of the 30m mast on a 78' RTW maxi yacht, which in delivery trim was probably about 42 tonnes.
The topmast is all you can see of the boat from the dinghy landing place, due to a fairly decent wave, breaking 100m inshore of the yacht's location. She was lying happily to a 105lb CQR in Rada Vinapu, an exposed open roadstead off Easter Island, in a decent breeze.

For two days, that anchor held perfectly, on 30m of 5/8" chain and all our best hawsers joined end to end. We weren't assuming anything: there were a minimum of six competent crew left on board, with instructions to bugger off at the slightest indication of a drag. And not come back until the seas went down!

A single anecdote proves nothing, but the skipper made all the purchase decisions on that boat, and he was possibly the best seaman in the Whitbread fleet of that era (mid 80s) - certainly up there with the likes of Tabarly. He certainly thought it was an adequate anchor. It was also noticeable he always seemed to get it to set on the first attempt. (As his vessel had no windlass, not even a bow roller, failure to achieve that was the sort of thing you would notice)

I'm pretty sure seafloors and waves and wind haven't changed too much in the intervening period.

However, one thing which HAS changed: Most modern humans appear to have been trained from birth (by business interests, presumably) to consider convenience to be an apex characteristic, often THE apex characteristic ... and adequacy is considered a concept from yesteryear.

That seems to suit the needs of the consumer-driven, growth-predicated economy very nicely.

(Please don't think I'm trying to win converts here, I'm just trying to pre-empt the derisive dismissal from the NewGen fanbois!)

PS: the other thing which has changed is that people use much bigger anchors and much smaller chains these days. The reasoning seems plausible at first encounter, but I find some serious flawed assumptions on deeper consideration and experimentation.
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Old 24-02-2014, 04:50   #33
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Re: Do I need a new gen anchor?

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Originally Posted by Nicholson58 View Post
Same issues on our boat. I bought a Rocna but the roll bar interferes with the bow pulpit.
Has anyone heard of cutting off the roll bar? Looks like a spade without it.
Hello!

I think Mantus is only roll bar anchor designed to work without the roll bar
Others depend more heavily on roll bar for setting properly.

Personally I would think about some modification to the pulpit itself, to adjust it to the use af ANY chosen new generation anchor

Best regards

Tomasz
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Old 24-02-2014, 05:44   #34
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Re: Do I need a new gen anchor?

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Originally Posted by ozskipper View Post
An anchor is only as good as the scope and the catanery Curve.

If your scope is too short and there is only a short length of chain your catanery will be dismal and the anchor wont set properly

That may be where the answer lies.
Following the useful links that Stu Jackson made are some vids from MaineSail where he shows that with very short, i.e. even 2:1 scope and therefore very little catanary still allows the anchor to lie flat, so increasing it won't help it to start to dig in. Once it has started, it will benefit from a little more scope and for holding, the more the better. I was surprised how low the anchor lies when dragged using such low scope.

In any event, I usually set with a lot more than that. 6:1 then shorten a bit. When setting fully, the chain is bar tight, so scope is important, but there is almost no catenary, so that is not a factor.
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Old 24-02-2014, 19:52   #35
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Re: Do I need a new gen anchor?

Quote:
Originally Posted by JonJo View Post
+1

We use a claw chain hook on the rode attached to a strong point and leave the chain to the windlass slack.
same here. we bring the manson supreme right up on the roller. about 2 feet behind the chain shackle we have a chain claw that keeps it taught. chain past that is slack, but gets one wrap around a large cleat and then straight in to the windlass.

the windlass is always left in 'ready to run the chain out' condition. just take the wrap of chain off the cleat, pull the anchor shank back an inch or two, release the chain claw, and over she goes....
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Old 24-02-2014, 20:44   #36
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Re: Do I need a new gen anchor?

Quote:
Originally Posted by Andrew Troup View Post
I have a photo I took of the top 10m or so of the 30m mast on a 78' RTW maxi yacht, which in delivery trim was probably about 42 tonnes.
The topmast is all you can see of the boat from the dinghy landing place, due to a fairly decent wave, breaking 100m inshore of the yacht's location. She was lying happily to a 105lb CQR in Rada Vinapu, an exposed open roadstead off Easter Island, in a decent breeze.

For two days, that anchor held perfectly, on 30m of 5/8" chain and all our best hawsers joined end to end. We weren't assuming anything: there were a minimum of six competent crew left on board, with instructions to bugger off at the slightest indication of a drag. And not come back until the seas went down!

A single anecdote proves nothing, but the skipper made all the purchase decisions on that boat, and he was possibly the best seaman in the Whitbread fleet of that era (mid 80s) - certainly up there with the likes of Tabarly. He certainly thought it was an adequate anchor. It was also noticeable he always seemed to get it to set on the first attempt. (As his vessel had no windlass, not even a bow roller, failure to achieve that was the sort of thing you would notice)

I'm pretty sure seafloors and waves and wind haven't changed too much in the intervening period.

However, one thing which HAS changed: Most modern humans appear to have been trained from birth (by business interests, presumably) to consider convenience to be an apex characteristic, often THE apex characteristic ... and adequacy is considered a concept from yesteryear.

That seems to suit the needs of the consumer-driven, growth-predicated economy very nicely.

(Please don't think I'm trying to win converts here, I'm just trying to pre-empt the derisive dismissal from the NewGen fanbois!)

PS: the other thing which has changed is that people use much bigger anchors and much smaller chains these days. The reasoning seems plausible at first encounter, but I find some serious flawed assumptions on deeper consideration and experimentation.
Yeah, yeah.

You have a point, however --

The structure of the argument is a bit like -- I once saw a 10,000 mile DX contact on HF radio made with a rusty coat hanger as an antenna; therefore all of your insulated backstays and so forth are consumerist-driven, modern decadance . . .

"Adequacy" is ok as a design concept for many purposes ("the perfect is the enemy of the good" etc.), but for ground tackle many consider "adequate" to be insufficient. Here is a really good case, in my opinion, for "as good as you can practically get it, up to and even including overkill, if that is reasonably achievable", as the proper design value.


As to bigger anchors and smaller chains -- that comes straight from good sources -- Steve Dashew and Peter Smith. The idea is that catenary is useless in extreme conditions, so weight in the chain which is not contributing to a necessary level of strength would be better put into the anchor. I think this is entirely sound. However, one need not go so far as to use G70 chain as Dashew does, which can't be easily regalvanized and which might be brittle.

I think anchoring altogether as a science has progressed greatly since I started cruising a couple of decades ago. The new generation anchors are just part of the equation. The result is a lot less anchor dragging, panic in the night, etc., objectively. I don't think we can dismiss this as "consumerism".
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Old 24-02-2014, 20:57   #37
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Re: Do I need a new gen anchor?

A friend of mine wrote this, seems like a pretty good option (OPTION, means HIS choice, your boat your choice, so no need to attack it...)

I forgot. The Rocna. All 20kg of it with 100ft of chain. The rest of the world can debate all they like. When I pull into a place like Bodega Bay at midnight and the fog is so thick I can't see the jetty 50 feet away to make an entrance, I drop my hook in the rolling ocean swells with the surf crashing (Foster says it's like staying in a cheap Best Western beside the highway), and I sleep. And in the morning I have a windlass to pull the beast up and I wouldn't trade it for anything. (I also wouldn't add more chain - this works perfectly in 25 to 30 feet of water - you let all the chain out and you tie off nylon at the preferred scope and don't bother with snubbers and chain hooks and all that stuff...)
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Old 24-02-2014, 21:14   #38
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Re: Do I need a new gen anchor?

Your present anchor is like a good twenty year old car. Relatively reliable and gets 18 miles per gallon. It is usable and if you are happy with it no problem. A new model (new gen anchor ) will be more reliable and in terms of car performance get you 36 miles per gallon but it will cost you to get the new anchor.
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Old 24-02-2014, 21:32   #39
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Re: Do I need a new gen anchor?

Perhaps a more apt analogy would be a new car that lasts forever vs. a Chevy Nova.
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Old 25-02-2014, 01:17   #40
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Thumbs up Re: Do I need a new gen anchor?

Quote:
Originally Posted by DoubleWhisky View Post
Hello!

I think Mantus is only roll bar anchor designed to work without the roll bar

Tomasz
Amazing how an intentional design characteristic took a couple of years to surface And if it was intentional and if it works - why the roll bar in the first place and why the roll bar now?

Tomasz, you were just being provocative- just ensuring no-one thinks its safe

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Old 25-02-2014, 01:50   #41
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Re: Do I need a new gen anchor?

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Originally Posted by Dockhead View Post




As to bigger anchors and smaller chains -- that comes straight from good sources -- Steve Dashew and Peter Smith. The idea is that catenary is useless in extreme conditions, so weight in the chain which is not contributing to a necessary level of strength would be better put into the anchor. I think this is entirely sound. However, one need not go so far as to use G70 chain as Dashew does, which can't be easily regalvanized and which might be brittle.

.
I appreciate that everyone says that G70 chain is, or might be, brittle - consequently it must be correct

but is there any evidence to support the statement. Have there been documented cases of G70 anchor chain breaking?

Original Rocna, Supreme, Excel all use hi tensile steel in their shank - have any of them snapped - showing brittleness.

I also appreciate that G70 chain should not be re-galvanised - in the same way a A514 anchor shank should not be re-galvanised. There is no mention of this deficiency in anchor shanks - why the paranoia with chain?

If I interpret what has been posted - lighter, stronger chain is useful, in that you can put some of that weight into an anchor, but you are not advocating G70 chain (for the reasons you outline) - what sort of chain are you suggesting might offer weight savings that could then be diverted to the bigger anchor?

Jonathan
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Old 25-02-2014, 02:03   #42
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Re: Do I need a new gen anchor?

My take on the adequacy question is that mostly what you get with a NewGen anchor is that it is easier to set. I consider this mostly as a convenience attribute, and of limited attraction provided I don't have undue difficulty setting the anchor I have.

NewGen anchors are also reported to hold better for a given anchor weight*. This may indeed be so, but again I'm not bothered, because I don't mind heavy anchors. The design I favour for the sorts of bottoms I consider most difficult (the genuine Bruce) performs very nicely in the heavier sizes.

*Interestingly, NewGen manufacturers themselves seem conflicted on this point, because their charts often recommend heavy anchors.

So my yardstick of adequacy is that an anchor is adequate to my needs if it holds the boat in any conditions I have yet experienced and stows compactly in my bow, and it is sufficiently convenient for my needs if I can set it without difficulty. I don't care if someone else finds that particular anchor difficult to set, or if it doesn't deliver good holding figures in anchor tests.

Anchor tests, in my experience, tell us how well an anchor will perform in the chosen test, and that's about where it ends. I don't really care how anchors perform in tests; i care how they perform at 3am in the real world.

The "conventional wisdom" on the catenary question, at least on the internet, is (I would venture) largely driven by the two guys Dockhead mentions, plus a couple of others. All I can say is that the reasoning of all these guys has gaping holes, and would not get signed off by any expert in kinematics.

Their explanations of the perceived limitations of catenary, are however entirely plausible to laymen, because these guys are basically gifted, experienced laymen. And all but one of them have a selling focus, which with the best will in the world will inevitably be inimical to absolute impartiality and objectivity. Having said that, I am convinced that they are all convinced that they are telling the exact truth on the matter.

I know one of the more influential guys personally and hold him in considerable esteem - but I would not get him to design an energy transfer system. Which is what a rode is, for the purposes of this discussion.

He would very likely get me to, though .... as long as he didn't know it as a rode. Rodes, he thinks he knows all about. We all do...
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Old 25-02-2014, 04:39   #43
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Re: Do I need a new gen anchor?

Hi, Jonathan

Quote:
Originally Posted by JonJo View Post
Amazing how an intentional design characteristic took a couple of years to surface And if it was intentional and if it works - why the roll bar in the first place and why the roll bar now?
I have not a clue
I do not understand fully the mechanics behind the Mantus setting, so I can only go after what the designers say...
And the people are happy with their Mantus anchors - it is most important thing

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Tomasz, you were just being provocative
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Old 25-02-2014, 14:49   #44
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Re: Do I need a new gen anchor?

Like most anchors that have survived their baptism of birth it works well in many seabeds - but on no account remove the roll bar and use it for overnight or long term cruising. Its an anchor and its on a boat - if something can go wrong it will and if it lands on its back it will never re-set.

It 'works' because a flow of water turns the sole, underside, of the fluke toward the water flow. If the boat is moving aft the water flow turns the anchor so the sole is facing the bow of the yacht, the heel of the fluke hits the seabed and falls shank toward the yacht - immediately ready to set. In this orientation it will set immediately. It does not take much water flow to induce this effect. Of course if the yacht is moving forward the opposite occurs and it falls and lies with the shank pointing away from the bow. If the yacht then moves backwards (so as to set the anchor) there is the chance it will simply stand up on its heel (it is a very wide heel) and can fall upside down. It will then never re-set. There are many scenarios to have the anchor on its back.

If you test it and find me wrong and that the suggestion was thus professional and safe - please post. I am more than willing to be shown to be incorrect.

I suspect this hydro-dynamic effect is to be found on other concave anchors to a greater or lesser extent.

Removing the roll bar will be perfectly sensible for very small vessels simply stopping to fish or have lunch. But I do not think many on this forum buy anchors for that purpose. The suggestion, of removing the roll bar, was not thought through and was not tested in real life - the video was great but misleading and dangerous. The danger is the idea has stuck - even now it is being repeated as gospel. Shame on the manufacturers.

It would be better if design quirks were tested in full by the manufacturers rather then making misleading claims and then quietly trying to forget them. The market is not the place to make design changes as most professionals would and should know. It might work for 'T' shirts but not for anchors.

Moths only appear when something of interest is lit by light - obviously many would want errors simply swept under the carpet where moths would not find them, shame on them.

Have a great day!

Jonathan
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Old 26-02-2014, 03:55   #45
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Re: Do I need a new gen anchor?

You well may be right Jonathan

At least Your expertise with different anchor designs is much wider than mine

Best regards



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