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Old 09-02-2011, 15:46   #76
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Originally Posted by CarinaPDX View Post
The fact that the ends are secured doesn't magically make the torque of the unlaying twist go away - it just prevents it from showing. There will be a torque applied to each end, and when the rode unloads and loads it can hockle. I have used 3-lay for a snubber and it usually does turn into a twisted mess - I don't do that anymore.
Yes, I understand your point. But there is an important distinction; the short snubber is a very tough application because the load comes and goes quickly, unlike a fiber rode, and it can hockle before the stresses even out. Also, as you explained, your snubber is not truly constrained at both ends; the chain can twist. So, true, but not relevant to my question. What if the 3-strand is truly prevented from twisting, which it is in most applications.

Off the topic a bit, but interesting trivia. Mountaineering (rock climbing) ropes have 12-16 parallel core ropeletts that are each individually twisted, but not to each other; they form a loose bundle. There are always an even number; half are s-twisted, and half are z-twisted, so that the bundle does not cause rope twist if loaded free hanging, which is common. This was a perpetual problem back in the day, when 3-strand ropes were used in the mountains.

Ropes are not simple.
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Old 09-02-2011, 16:18   #77
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But with chain (weight), as long as it IS (mostly) on the bottom, the pull will increase the effectiveness of the scope. Don't know if that comes out right, but looks good to me.
There's an easy way to test this. Lay out 100 meters of chain on a sandy beach. Now pick up one of the ends and try to drag the chain.

You'll be amazed at how much energy it takes to move chain.
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Old 09-02-2011, 17:07   #78
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There's an easy way to test this. Lay out 100 meters of chain on a sandy beach. Now pick up one of the ends and try to drag the chain.

You'll be amazed at how much energy it takes to move chain.
My boat is heavier than me and has more power than me when the wind is blowing over it or the tide is running
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Old 09-02-2011, 18:45   #79
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There's an easy way to test this. Lay out 100 meters of chain on a sandy beach. Now pick up one of the ends and try to drag the chain.

You'll be amazed at how much energy it takes to move chain.

a. That would be about 240 pounds of chain. Try to pull a 250-pound anchor.

b. If the wind is blowing anywhere near storm levels, the chain isn't on the bottom. Mathematically impossible.

c. It could be that there is simply enough chain for ridiculous scope. Then up-size the anchor a bit and see a.

We're going in circles again.

Abrasion resistance I think we all get. No argument is presented.
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Old 09-02-2011, 19:43   #80
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Yes, HT shackles are available and are a great solution if you have them. The normal cheap shackles on the Hamilton site are "load rated" (i.e. don't provide SWL) and for the good US galvanized shackles it requires 1/2" to get the 2 ton rating of the 5/16" HT shackles. To get 2 tons out of the swivels it takes 5/8" (galvanized or stainless) unless you opt for the expensive ones designed to go over rollers smoothly. All that for HT 5/16" chain. No wonder there are failures at the swivels...
Wrong -- look here SHACKLE ANCHOR 3/8" USA 2TON HI TEST SLVR PIN 105393
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Old 09-02-2011, 20:01   #81
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SailFastTri-

I'm not sure what you think I said is wrong, but i'm pretty sure you typed before you checked. Reread the first sentence I wrote which you quoted: I did indeed give credit to the HT shackles, which you then referenced. Everything else I talked about were the none-HT shackles and swivels. Perhaps you didn't figure out that "HT" means "High Tensile"?
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Old 09-02-2011, 20:56   #82
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a. That would be about 240 pounds of chain. Try to pull a 250-pound anchor.
I doubt that my windlass could hoist a 250lb anchor that had been properly set. On the other hand, it would have no problem retrieving an equal weight of chain.
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Old 09-02-2011, 21:15   #83
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SailFastTri-

I'm not sure what you think I said is wrong, but i'm pretty sure you typed before you checked. Reread the first sentence I wrote which you quoted: I did indeed give credit to the HT shackles, which you then referenced. Everything else I talked about were the none-HT shackles and swivels. Perhaps you didn't figure out that "HT" means "High Tensile"?
Sorry -- I was too quick to reply. Apparently we're on the same page.
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Old 09-02-2011, 21:37   #84
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When using a chain/3-strand nylon rode, my darn anchor always comes up backwards on the anchor roller. Kind of like buttered toast falling on the floor. Hence the swivel.
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Old 10-02-2011, 05:48   #85
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So do shackles and every link of chain.

I don't consider swivels "essential", don't put words in my mouth. But they are helpful on some boats, and good quality ones are fine.

There's no lesson at all to learn unless you detail the exact swivel model and the particular failure it suffered. Tarring all in a group with the same brush by way of an unknown anecdotal failure - if that's not "arrogant" I don't know what is.
Sorry for the delay in answering.

Swivels, chain links, rope, and anchor are single point of failure elements and their respective probabilities of failure are added to obtain the total probability of failure. With the exception of swivels, all other components are generally accepted as necessary (with variations in length, strength, materials, etc.)

So, by removing a non-necessary component (the swivel), we also remove its probability of failure, irrespective of its value, from our equation, without removing much virtue from the system.

Of course, I say all this for my own benefit, because most knowledgeable people already know it.
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Old 10-02-2011, 06:10   #86
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It's not non-necessary to some boats and some boaters.

But, a good quality swivel installed correctly is as safe as a shackle. Possibly safer.

I don't understand how you can think in such circular logic. You might just as well rant that shackles must never be used, because the majority available are cheap low grade junk that are probably weaker than the chain.
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Old 10-02-2011, 11:44   #87
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It's not non-necessary to some boats and some boaters.

But, a good quality swivel installed correctly is as safe as a shackle. Possibly safer.

I don't understand how you can think in such circular logic. You might just as well rant that shackles must never be used, because the majority available are cheap low grade junk that are probably weaker than the chain.
Thanks for your input. After having met briefly Alain Poiraud (designer of the Spade anchor) here a few years back, and then witnessing your internet person qualities, I can assure you that if I ever buy another anchor, it will be the one represented by the most reasonable person. Not yours. Well, perhaps a Manson, they are the same and cheaper, aren't they?
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Old 11-02-2011, 18:51   #88
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I doubt that my windlass could hoist a 250lb anchor that had been properly set. On the other hand, it would have no problem retrieving an equal weight of chain.
OK, I exaggerated. I took poetic license and stretched it, to make a point. Dragging 100 meters on a beach was not a fair illustration either, so we were both playing.

Even one size up in anchor would add more holding than 200 feet of chain. Chain is good for abrasion and very good for short scope in a crowded fair weather anchorage, but remains a very inefficient way to gain holding power in extreme conditions.
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Old 06-03-2011, 18:20   #89
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Re: Nylon vs Polyester

Back to the original question on this thread, for those of you who do use polyester anchor rodes, can you name which specific brand and type of polyester you're talking about? I'd like to compare the manufacturer's specs., cost, etc. on the polyester vs. the standard 3-strand nylon (that I have been using for more than 30 years).

Also, I have to say I have been in some anchoring and parachute sea anchoring situations where I could feel the significant stretch happening in the nylon line. To my unscientific eye and sense of motion it appeared to me that this was relieving the stress on my boat fittings, the line itself, and what it was attached to. I have never observed this overheating/melting phenomena through numerous gales, a couple of hurricanes, etc. Not saying it doesn't happen, just that it must be a pretty rare occurence if you are using a decent-sized line.

In fact that might be the easier, cheaper solution to having too much stretch in your nylon--go up a size or two in diameter, and gain some chafe resistance too.
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Old 06-03-2011, 18:59   #90
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Re: Nylon vs Polyester

We use multiplait here. 3-strand for anchor? Never in my ship ;-)

Hard to say what make it was. Came from Germany just before the Chinese era. Could be some German stuff. (Gleistein, if sth like this exists?)

(OK, found it here: Gleistein - Geo Yacht productsheet for rope GeoSquare Polyester)

I reckon the Polyester has stretch enough so that when the rope is long, you get all the snubber rubber effect you need, if not too much.

How about UV resistance? I think plain nylon fares poorly in this respect, but then again an anchor rode is not the same like an .6 oz nylon spinnaker cloth, is it.

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