Kedge Anchor with no chain and Spectra Dyneema rode.

[Ken Z]

I have always used three stran nylon 20' of chain and crosby or wilcox(sp?) a usa galv. brand ,china steel i dont trust. 3 strand nylon gives you stretch, chain helps you set the anchor and saves it from rocks and coral. A piece of leather is good chafe protection on your chock, or just take in or let out a foot to change wear spots.

[Factor]

Originally Posted by noelex 77

...Dyneema (or Spectra, they are essentially the same fibre)

similar but not the same or even essentially the same. In so far as anchoring is concerned - yep I agree they are close enough to the same thing, but for other purposes - very different. Spectra's creeping is a definite let down on halyards and shrouds etc compared to Dyneema.

for anchors is its superior abrasion resistance over lines like nylon that have been traditionally used. I think we are going to see much more use of Dyneema for anchor rodes in the future.

The lack of stretch in Dyneema just means you need a snubber like you would with chain. The other challenge is to ensure the line will sink, but this is solvable.

I like spectra and Dyneema, and they have some great properties, and in some applications they have taken over from traditional answer very quickly - eg winch cables on 4Wds. But I would still use nylon, two very important features on anchor rodes are that they sink, and that they stretch. Spectra and Dyneema do neither well. I am with thinwater on this.

[Stumble]

Originally Posted by noelex 77

Dyneema/Spectra generally really needs to be spliced not knotted. Fortunately single braid is easy to splice.

I think the best option is to have the line in sections where the likely desired attachment positions are situated and attach the snubber via a soft shackle.

I don't think this is just an option for a kedge. It has some potential for use on the primary anchor where weight is critical (for example with no anchor winch).

Abrasion resistance is still a concern. While not as good as chain, Dyneema has much better abrasion resistance than polyester or nylon rope rodes.

I havethought about this a good bit, and frankly don't like any of the answers I have come up with. The best option I have is having the anchor line run thru a larger dyneema line, the large line is just a short pennant that slides up and down the anchor line with an eye spliced inthe other end then the eye attached to a nylon snubber.

The problem of course is that it would be tedious to move the larger pennant up and down the anchor line to the right place every time you needed to anchor.

I have yet to figure out a good way to attach a snubber midspan. Maybe someone else will devise such a solution.

[Fuss]

Thanks for all the replies so far, the reason I asked is that it is so much easier if you remove the chain and in some conditions Fortress says the chain is not necessary to help set, for example in soft mud chain pulls the shank down and stops the flukes from bedding in... however this gets too much into other detail that is not so important to this thread.
It is interesting for me what others have done to use their kedge without chain but retain strength and not have the worry of chafe, thus my original question. Try your fortress without some chain...it still works just the same and makes life so much easier.

[UNCIVILIZED]

In terms of chain, if the anchor is primarily a kedge, or one which you don't commonly leave set for long, then you can go to a higher schedule of chain, including a transport chain, which only has light galvanizing, so that it's far lighter in weight per unit of strength. Though it'll need to receive a good bit more TLC (rinsing) than standard chain.

For using bare Dyneema for things like anchor rode, how does one handle cleating it off? Including dealing with it's low melting point, & tremendous aversion to heat. Since it wouldn't take too much line surge to overheat the section of bare Dyneema on a cleat, if there's any room at all for it to move. And I can't see being able to 100% prevent such movement. Since it's quite easy to melt nylon lines due to such movement when a boat's surging heavily.

One other thought for an anchor that's purely a kedge used for ungrounding yourself would be to shackle a stout block to the anchor. Or to a chain leader attached to the anchor. And then use a rode which has half of it's length composed of Dyneema, & half of conventional cordage. With the 2 shackled together such that you attach the bitter end of the Dyneema to a deck padeye or cleat, & then pull in on the standard cordage on the line's other end. Either via a winch, or windlass, until the juncture of the 2 lines gets winched to the boat.

If you did this, then it'd be fairly easy to have quite a long line for kedging that would be fairly light weight, but very strong. Along with the perk of it giving you a 2:1 purchase for un-assing yourself off of a piece of real estate. Which at times surely could come in handy. The extra pulling power I mean.


PS: If you want a metal leader near the anchor that's lighter weight, & that doesn't inhibit burying, you can use rigging wire. Though watch out for meat hooks when handling it. And of course it'll be more sensitive to corrosion than chain. But in some areas you see commercial vessels that use it as primary rodes, with large spools of it mounted on powered drums on deck.

[Stumble]

Originally Posted by Factor

similar but not the same or even essentially the same. In so far as anchoring is concerned - yep I agree they are close enough to the same thing, but for other purposes - very different. Spectra's creeping is a definite let down on halyards and shrouds etc compared to Dyneema. I like spectra and Dyneema, and they have some great properties, and in some applications they have taken over from traditional answer very quickly - eg winch cables on 4Wds. But I would still use nylon, two very important features on anchor rodes are that they sink, and that they stretch. Spectra and Dyneema do neither well. I am with thinwater on this.

So far as I am aware Spectra and dyneema are chemically identicle fibers with different manufacturers. DSM created it, then early on leased the manufacturing of it to Honeywell for the NA market. Honeywell branded it Spectra.

The earl you differences had to do with slight manufacturing differences, and that the US rope manufacturers were using a slightly different braid angle than the European ones. The US stuff was wider angle braids, similar to the braid angles of polyester, while Europe was using low angle braids, like polypropylene (ski ropes).

Since then everyone has pretty much collapsed to low angle, braids and of course developed post manufacturing treatements to increase physical properties (head setting, load pulling, etc.).

I feel someone has contrary information I would really like to read it. Because this is the story I have been working under for years. If I am wrong I would like to correct myself.

[crabcake]

Mooring ropes with Dyneema® show minimal wear after six years in service on VLCC

[noelex 77]

Originally Posted by Factor

similar but not the same or even essentially the same. In so far as anchoring is concerned - yep I agree they are close enough to the same thing, but for other purposes - very different. Spectra's creeping is a definite let down on halyards and shrouds etc compared to Dyneema.

Manufacturers try to differentiate their product and it easy to fall for the marketing hype.

There is a simple explanation of the properties of different rope types here:

Fibre Explanations : Sydney Rigging Specialists

"Spectra® and Dyneema® are basically the same product but registered trade names of different companies. Spectra® is the trade name of Dupont from the USA and Dyneema® is the trade name from DSM in the Netherlands."

DSM won a recent court case and now Dupont pay royalties.

[noelex 77]

Originally Posted by crabcake

[URL="http://gcaptain.com/mooring-ropes-dyneema-show-minimal-wear-six-years-service-vlcc/"]

Thanks for the link. It is incredibly wear resistant compared to nylon and polyester, but it is still a long way short of the chafe resistance of chain.

This is one of our Dyneema soft shackles after some prolonged hard use:



Will Dyneema survive the following sort of treatment?

[thinwater]

Originally Posted by UNCIVILIZED

In terms of chain, if the anchor is primarily a kedge, or one which you don't commonly leave set for long, then you can go to a higher schedule of chain, including a transport chain, which only has light galvanizing, so that it's far lighter in weight per unit of strength. Though it'll need to receive a good bit more TLC (rinsing) than standard chain.

For using bare Dyneema for things like anchor rode, how does one handle cleating it off? Including dealing with it's low melting point, & tremendous aversion to heat. Since it wouldn't take too much line surge to overheat the section of bare Dyneema on a cleat, if there's any room at all for it to move. And I can't see being able to 100% prevent such movement. Since it's quite easy to melt nylon lines due to such movement when a boat's surging heavily.

One other thought for an anchor that's purely a kedge used for ungrounding yourself would be to shackle a stout block to the anchor. Or to a chain leader attached to the anchor. And then use a rode which has half of it's length composed of Dyneema, & half of conventional cordage. With the 2 shackled together such that you attach the bitter end of the Dyneema to a deck padeye or cleat, & then pull in on the standard cordage on the line's other end. Either via a winch, or windlass, until the juncture of the 2 lines gets winched to the boat.

If you did this, then it'd be fairly easy to have quite a long line for kedging that would be fairly light weight, but very strong. Along with the perk of it giving you a 2:1 purchase for un-assing yourself off of a piece of real estate. Which at times surely could come in handy. The extra pulling power I mean.


PS: If you want a metal leader near the anchor that's lighter weight, & that doesn't inhibit burying, you can use rigging wire. Though watch out for meat hooks when handling it. And of course it'll be more sensitive to corrosion than chain. But in some areas you see commercial vessels that use it as primary rodes, with large spools of it mounted on powered drums on deck.

The problem with high grade chain is that the shackles are basically unavailable above grade 43. And it will still be chain, when it comes to dragging on deck. Dyneema is better.

A a leader, the solution is to cover it with a webbing chafe guard. No problem cleating to handle and break-out, based on experience.

You only overheat nylon if you are over the WLL. It would fail anyway. Additionally, At least I am proposing Dyneema only for the leader (20'); there will still be nylon. I am only replacing the chain, which ain't easy to cleat either.

No one is going to use rigging wire. It's been discussed for 75 years (old Danforth documents) and no one is going to do it for obvious practical reasons (good luck cleating that for break out).

And no, Dyneema is not chain. I used Dyneema during some anchor testing around rocks, because it was something that needed testing. It didn't do badly, but after you watch rodes wrap around rocks it becomes obvious that chain the the best answer. I only use Dyneema/webbing for sand and mud. I have a 20' piece of chain I can swap.

[crabcake]

Originally Posted by noelex 77

Will Dyneema survive the following sort of treatment?

You're very welcome Noelex!

I seriously doubt that Dyneema in its current formulae will take the kind of punishment marine coral can dole out! I won't say never, because never is a long time

Now these folks seem to be doing some neat stuff with Dyneema as a base. Maybe in the not too distant future they'll come up with something that can withstand the punishment anchoring generates?

[buzzstar]

Originally Posted by Fuss

Does anyone have an example of their setup...
Shackles, length of dyneema, chafe protection used, splicing or knots used, size of anchor, size of your boat, thimbles or not etc..

It would be interesting for us all I think.

At the moment , I have a FX55 fortress attached to 100m of 16mm sinking 3 strand with a thimble and a big unrated stainless shackle.

My boat is 27 tonnes.

Originally Posted by wsmurdoch

If the word "kedge" means the anchor on the stern that is carried out in the dinghy to recover from navigational mistakes, the light weight and no stretch of Spectra would be a good thing.

There may be a terminology gap in addition to the usual common language problems. My interpretation is that the OP is using the Fortress as his kedge (or secondary) anchor. Another anchor is his bower (or primary) anchor. Some of the responses relate to the verb, "kedge," but unlike wsmurdoch, the posters may not recognize the other meaning. We see so many references to kedging off a grounding that some of us, myself included, may forget the existence of two meanings. Most cruisers not only carry a bower, and kedge, but probably one or two other, less frequently, used anchor types. Perhaps a really light "lunch hook," and a really heavy one, such as a Fortress for storms and such. Yes, I know, for some the lunch hook may serve as their kedge, so just like all things anchor, it is not an exact science, but is an art balanced by science, mathematics, and skill. Seamanship too if you consider it a separate and category.

[Factor]

Originally Posted by noelex 77

Manufacturers try to differentiate their product and it easy to fall for the marketing hype.

There is a simple explanation of the properties of different rope types here:

Fibre Explanations : Sydney Rigging Specialists

"Spectra® and Dyneema® are basically the same product but registered trade names of different companies. Spectra® is the trade name of Dupont from the USA and Dyneema® is the trade name from DSM in the Netherlands."

DSM won a recent court case and now Dupont pay royalties.

You may fall for marketing hype, I don't.

Spectra creeps under prolonged heavy load and Dynemma doesn't, wonder how that is. It may not be relevant in the lower performance end of life, the difference is very noticeable on high performance multis. Thats actual real life experience, not internet truth.

Got a citation for that court proceeding reference?

[Stumble]

Originally Posted by Factor

You may fall for marketing hype, I don't.

Spectra creeps under prolonged heavy load and Dynemma doesn't, wonder how that is. It may not be relevant in the lower performance end of life, the difference is very noticeable on high performance multis. Thats actual real life experience, not internet truth.

Got a citation for that court proceeding reference?

Dynema absolutely creeps under load, you are welcome to go check the DSM website for creep over time engineering data here. https://www.dsm.com/products/dyneema...-property.html In fact factoring in dyneema creep data is what is necessary for using it as standing rigging.

I think you are thinking of is vectran that has effectively zero creep (about the same as stainless). But all flavors of dyneema creep to varying degrees.

[charliehows]

I use about 10 ft of chain then 20mm nylon rope. I think a bit of chain is good to encourage the anchor to bite - 10 ft isnt a problem when laying out from a dinghy. As far as dyneema for the rode - I'd consider doing a tightish 3 strand plait so you can get some stretch into it, otherwise its strength and abrasion resistance makes it a pretty good fit. I've found a perfect use for dyneema - on my boom brake which is a wichard style - thin rope, quite slippery, abrasion resistant, very strong.