Dyneema Anchor Rode

[Dockhead]

Originally Posted by estarzinger

They worked awesome, up in Greenland and Newfoundland 3 years when I was soloing.

But we have given up boating . . . . so no new developments/experience with them. New England Ropes uses the concept in their 'cyclone mooring pendants' product and still has a 100% record.

I do have snubbers on board even if I don't use them much. I think I'll make up a couple of those over the winter time. I was using one of them as a temporary midship spring for single handed docking, and lost it overboard this summer.

[UNCIVILIZED]

Originally Posted by Dockhead

I'll definitely talk to Thinwater.

Dashew is pretty categorical about polyester vs nylon, and I find his arguments pretty convincing. Have you read this?

Attachment 156504

Yep, I've read it, & it is convincing. Though as Evans alluded, some of it is dependent on/related to boat & rode size. And I really want to get a copy of Thinwater's book on this topic before I decide one way or another. Not that both options won't work if done correctly. Plus it's been ages since I read Practical Sailor, & I think a lot of his stuff is published in various issues.
Any links to something more recent by the Dashews on this topic?


EDIT: There are a bunch of lines that are dyneema blended with other fibers, & they might make good choices for what you're looking at. Along with various other ropes used in commercial maritime & land based industries. Which, since they're not for recreational marine use, the prices tend to be lower. For example, the stuff Seaworthy Lass found & plans to use in her JSD.

[Benz]

Originally Posted by estarzinger

If you mean their "Anchorplait© to Chain Splice" . . . be aware that the windless manufacturers do not like or recommend it. It is easy to make and is high strength (when done correctly) and a decent splice if you are not using a rope to chain gypsy, BUT the windless guys have had cases where a link turned a bit sideways (inside the splice, where the rope is taking the load rather than the chain) and jammed in the gypsy and stalled the windless occasionally either hurting the gearbox or the motor. They pretty much all recommend some one of the back/loop splices where the chain links are unconstrained, and there are various tips/tricks for making these lower bulk and more flexible so they run thru the gypsy pretty well.

I agree with your general thought on materials. I'd personally go nylon, but if I had some particular reason to be concerned about chafe I'd use polyester (plait in both cases).

I don't really like the splice either--it has an awkward finish. But I did one for a Gunboat recently that requested it specifically, and I know that it works, even if it's not pretty. I far prefer a back splice from the last link, but the customer was holding all the cards--nice, crisp, greeny-gray ones--in this case.
But for those who want the strength of Dyneema with the grippy-ness of polyester, why not try something like NER's Salsa? 8-strand Dynemma/poly blend. Perhaps it only comes in small sizes.

[Seaworthy Lass]

Originally Posted by Pete7

If the lengths are 20m then that would suggest a total of 9 knots and splices between the anchor and the boat, is that a good idea for an anchor rode?

Pete

We are planning this as emergency anchor rode (to be used with our standard snubber) and 80m will be plenty for this, resulting in 3 joins when used the maximum amount, and zero, one or two joins otherwise. I have no fear using well made eye splices, so I don't think this is a problem.

I think this length of dyneema/acera will make an excellent emergency system, doubling for other uses when needed. The low weight, low volume and high chafe resistance are big drawcards. It should not be too difficult to weigh it down a little so that it sinks. Retrieving the line is the main issue, but by tailing the line around the capstan (or a winch) this should be possible.

I would not like to use all rope rode rode permanently. Snorkelling I have seen chain caught under far too many underwater obstructions, sometimes at quite acute angles. Rope could chafe through horrifically quickly in these conditions.

SWL

[Benz]

Originally Posted by Dockhead

I'll definitely talk to Thinwater.

Dashew is pretty categorical about polyester vs nylon, and I find his arguments pretty convincing. Have you read this?

Attachment 156504

A couple of thoughts after reading that PDF:
1) Dashew's line size selection seems on the slim side to me. I had 5/8" nylon on my 27-footer! And I carry 3/4" nylon on my 31' cutter. He was doing 3/4" on a boat twice the length!
2) It's not always possible to let out more rode--some anchorages are pretty tight and neighborly.
3) A big reason boats sail around at anchor is because of an absence of real keel. Without passing judgment on fin keels and spade rudders in this place, I'll point out that it's unfair to rope rodes to blame them for the consequences of bad boat design.
4) There is no reason ever to let a nylon rope saw on a hawsehole or chock. That is simply bad seamanship. When the rode is at the desired length, rolling-hitch a shorter, cheaper sacrificial line to it. It can even be dyneema. Then lead that through the chock and belay. That way the expensive nylon rode doesn't get harshed on.

That being said, I usually anchor on all chain, but my kedge is on nylon with a short chain leader, and that's the one I deploy for serious blows. 200' of nylon makes a very comfy ride!

[Seaworthy Lass]

A couple of examples of chain caught under rock. Permanent use of all rope rode (especially nylon or polyester) would result in sleepless nights for me.

In the first photo the chain passed completely under the rock and can be seen emerging at the centre top.
In the second photo with every gust the chain veered up, sawing back and forth under the rock as the boat swung around.

Even in rockless anchorages I have seen all sorts of unexpected debris that could potentially chafe rope eg old engines, parts of wrecks, even bits of planes.

[Seaworthy Lass]

For those of you who think you rarely anchor near rock, if there is one around, Murphy's Law says your rode will snag it .

I would have sworn this was an all sand anchorage with only sparse patches of scattered weed, but this is what the chain managed to encounter:

[BigBeakie]

Wouldn't it be great if there was anchor chain that is strong but lighter?

We are in final testing of a new chain for our new 50' cat. I definitely wanted a full length chain rode for deeper anchorages ( Alaska, BC, deep Sth Pacific spots etc.) but wanted something lighter.

Serendipity led me to a new chain that is G100 and a galvanising process that promised better corrosion protection. After as much book research as I could reasonably digest and confirming the break testing results, I took the leap and ordered 120 meters of G100 8mm. It weighs 1.45 kg/meter.

My sample broke at 11 Tons kgf at a certified testing facility. But best of all, it is not brittle, which was my main concern. It has about 20% elongation to break, my sample was 22%. I also got all the strong Omega links galvanised at the same time. No sense having stronger chain and then using weaker links.

The galvanising is 100micron Armorgalv, ( normal galv. is about 30 micron, US Navy and Coast Guard spec is 60 micron I believe) and from what I have seen of 18 months of constant seawater immersion, the corrosion protection should be excellent.

I've got a sample length soaking in a surf zone getting pounded, so I'll see how the durability goes while the boat is being built.

Any other ideas for testing would be appreciated. I still will have an emergency and /or storm rope rode, so this thread is excellent info. Thanks to all.

[UNCIVILIZED]

You could drop a piece of it into a bucket along with something electrically noble, & add a bit of electricity, to test it's corrosion resistance. Or drag it through the sand extensively behind a truck or off road vehicle. And with any of these tests, or others that you think up, do the exact same test against a piece of chain who's properties are known. This will give you a benchmark to compare the new stuff to.


BTW, what do you plan to use in terms of shackles? Or does it have oversized links on the ends? Though even with these, a situation may arise where you have to connect it to things using one of it's regular links.

[skipmac]

I like my all chain rode. In addition to not being cut by rocks or coral, ability to attach snubbers and a few other things I really like the ease and convenience of hoisting all chain rode with windlass.

The ideal solution to me is to move the chain farther aft. No sure how Dashew does it but just visited a friends boat with a great setup. The boat is aluminum with a channel for the chain running under the foredeck to the windlass just forward of the mast. The chain then drops down a shaft to a chainlocker under the floor. Weight is all centered and you can carry as much as you like.

I had a boat years ago with a similar solution. Didn't have the channel under the foredeck but did have the chain locker farther aft. The PO had a nice, wood, channel made that laid on the deck for the chain to slide through without gouging the boat.

[BigBeakie]

Originally Posted by UNCIVILIZED

You could drop a piece of it into a bucket along with something electrically noble, & add a bit of electricity, to test it's corrosion resistance. Or drag it through the sand extensively behind a truck or off road vehicle. And with any of these tests, or others that you think up, do the exact same test against a piece of chain who's properties are known. This will give you a benchmark to compare the new stuff to.


BTW, what do you plan to use in terms of shackles? Or does it have oversized links on the ends? Though even with these, a situation may arise where you have to connect it to things using one of it's regular links.

Thanks Unciv.

I've already planned to drag it on a local beach, and alongside as many different other brands as I can rustle up. One test sample has been used in constant anchoring use, mostly sand, for 18 months, and it looks brand new.

It can have larger end links added during manufacture, but on mine I'll be using Omega 8mm links. If using shackles, you'd have to look up the breaking spec of the appropriately sized Crosby, Campbell or similar with a pin diameter of 10 or 11mm.

On the 8mm G100, there is 11.7mm ID link space for shackle pin.

Photo is the Omega link on G100 8mm chain and the same chain after break test with the broken link at the end. The link length on the unstretched chain is 39.5mm, and the break sample the links are 43.0 to 43.5mm.

[mattyc]

Where can one view the specs on Acera rope with working/breaking strength given in pounds?

[transmitterdan]

Originally Posted by mattyc

Where can one view the specs on Acera rope with working/breaking strength given in pounds?

1kN is about 225 lbf (pounds force) within the margin of error.

Many rope specifications just give breaking strength and leave working strength up to individual user safety factor choice. So you may not find safe working load listed anywhere or you may find it for some ropes.

[thinwater]

The snubber/catenary arguments can get pretty wild sometimes, with people saying catenary works fine, and other just as certain it does not. The real answer is that both may be true, which makes sense there are smart, experienced people on both sides of the debate.

If the water is shallow (>15 feet) the chain catenary will NOT absorb enough energy if steep waves arrive. Even at relatively long scope, there simply is not enough elongation between the lulls and the gusts. I'm not saying the chain is rod-straight, only that the difference in length between the gust an lull isn't much, just a foot or so.

In this circumstance, polyester is worse than chain. There is no catenary and there is not enough out to absorb impact. It can be MUCH worse. I tested it and loads were terrible.

However, if the water is >30 feet deep and you have >300 feet of chain out, then the catenary remains effective in some pretty extreme conditions. The grade of chain, scope, and boat are all variables, but once there is enough chain out, impacts are absorbed. If >300 feet of chain are backed by polyester, that's a good way to save weight and shock does not matter. The polyester will stretch a little.

200 feet of chain + polyester presents an interesting challenge. It is not enough chain to be safe in all conditions. A long nylon snubber is still a good idea if it will get really rough. However, attaching a snubber to polyester is a challenge. A rolling hitch will slip. A pair of prusic slings made from polyester cover Dyneema or Dyneema/polyester blend will hold well (a single may slip at high load), but an Amsteel sling will slide. So if the polyester is deployed, you either have to face this challenge, or deploy at least 100 feet of polyester. What you do not want to do is deploy 200 feet of chain and 30 feet of polyester with no snubber; it might get bumpy, if it blows hard.

One of the most dangerous combinations is 50-100 feet of chain + nylon, and no snubber in shallow water. They deploy the chain, only 10-20 feet of nylon. The nylon chafes, the load cycles over the WLL, and rope gives. This was not the fault of the nylon, they simply used it wrong.

----

It's an interesting question, which is why I kept my mouth shut and listened. I generally anchor shallow (catamaran), so 100 feet of chain + 35-foot snubber works really well. If it is deeper, I have nylon and use prusic slings. But perhaps if I was rigging from scratch, I would use polyester, pruisic slings, and a nylon snubber.

The truth is, I'm not too concerned about chafe or cyclical loading. Because I use a bridle, the rode is not over the roller and cannot chafe. The bridle is carefully rigged and does not chafe, at all. Because there is 100 feet of chain, the rope is not on the bottom. And because the snubbers keep the load (measured) below 10% of the BS of the rope even at 60 knots, fatigue is not possible.

[thinwater]

Another thing I have been playing with for several years is a rode with NO CHAIN. Yup, that's right.

Before you have a heart attack, this is for a kedge that is ONLY used for moving the boat or as part of a V-anchor rig. Based on a Fortress anchor, it is much easier to move around deck and in a kayak or dinghy. Because of the use, it does not move along the bottom, since in both systems, yawing is controlled. I'm not sure I would use this for V-rigs if coral and rocks were common, but they are not where I sail (soft mud with shells). But if there were rocks and coral, I probably wouldn't be using the Fortress either.

Chain catenary is counter productive when kedging. This should be obvious. The weight of chain is also problematic with Fortress anchors when setting in soft mud--lighter is better.

Finally, I do use a 20-foot leader for chafe. Over strength Amsteel covered with a free floating chafe guard, which by virtue of its freedom of movement, is virtually chafe proof, even over rocks. Tubular climbing webbing, attached only at the anchor end, but fully covering the spliced eye.

BTW, Dyneema without a cover is a bugger to handle. It's practically impossible to cleat when breaking out an anchor. I think it is dangerous to work with, enough reason not to consider it for this. With the webbing cover it cleats and handles just fine.

Something to try, for kedge anchors only. Food for thought. It is MUCH easier to use.