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Old 19-03-2017, 01:59   #1
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Kedge Anchor with no chain and Spectra Dyneema rode.

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.
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Old 19-03-2017, 02:33   #2
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

No fuss really.I tie the nylon directly to the anchor. Granted my cat is only 26 ft long and the kedge has been used in sheltered waters,but with a strong tidal flow.Sometimes simple is sweet.
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Old 19-03-2017, 03:19   #3
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

Spectra and Dyneema are two different things and the least desirable for anchors. Use Nylon.
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Old 19-03-2017, 03:51   #4
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

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Spectra and Dyneema are two different things and the least desirable for anchors. Use Nylon.
The reason everyone is talking about Dyneema (or Spectra, they are essentially the same fibre) 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.
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Old 19-03-2017, 06:33   #5
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

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. We have a FX-16 with 25 feet of 5/16 BBB chain and 250 feet of 1/2 nylon for a stern anchor. The weight of the chain is a little bit of a hinderance getting the kit into the dinghy for the trip away from the grounded boat. The nylon can get quite scary as it stretches and stretches with me right over the winch. There is a lot of stored energy in the line just waiting to tear me to pieces. Lighter weight and no stretch would be real benefits.

I also use my stern anchor rode in our marina when a hurricane is forecast. The marina crew takes it from the stern of my boat, across the fairway, and to a piling on the dock opposite. Tightened up, it prevents my boat from surging into the dock ahead of me. The almost spider-web of lines that results would also stop any loose boat from going anywhere. The deployed length is 100 feet, and truthfully, nylon is too stretchy for the service.

I do have some questions about reliably knotting Spectra. It is so slick. How would you attach a snubber? How would the marina crew tie it to the piling?
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Old 19-03-2017, 06:59   #6
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

Generally speaking-no anchor will work without a chain!
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Old 19-03-2017, 07:05   #7
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

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Originally Posted by wsmurdoch View Post
I do have some questions about reliably knotting Spectra. It is so slick. How would you attach a snubber?
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.
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Old 19-03-2017, 07:07   #8
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

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Originally Posted by Fuss View Post
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.
I use a Dyneema leader (in place of chain) with a nylon rode with a Fortress, but I would never use a Dyneema rode. In fact, I am a strong proponent of long snubbers when chain is used.

In addition to terrible shock absorption characteristics, Dyneema is also a handling problem. Very hard to handle or cleat, I don't know how you would attach a snubber (which you will need) and only a reel windlass could handle it. The negative catenary is interesting and could be debated for a week, though I doubt it actually very important, in the overall scheme. Interesting, but a lot of important unanswered questions.

A a pure kedge (hauling a boat off the mud) a non-stretch rode is actually better in some ways. Nylon stretches miles and the recoil can be scary and dangerous. I like old polyester halyards (some stretch) for kedging. Again, the problem with Dyneema (unless covered) is handling. Even then, it must be large enough for the winches.

The leader is 20' and is covered with 1-inch tubular webbing as a chafe guard. The line is over strength and I do not use a thimble since there would be no space for it under the chafe guard. Dyneema does not loose significant strength around a bend, but the extra chafe protection of a thimble would be nice. Or you could use a SS shackle and there would be no chafe.

Sail Delmarva: Replacing the Chain Leader with Dyneema--A Better Secondary Rode?
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Old 19-03-2017, 07:16   #9
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

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Originally Posted by noelex 77 View Post
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.
If the issue is no windlass, then Dyneema is too small to handle manually.

The section idea is interesting. I had not thought of that, and it would work with a reel winch.

But wouldn't a nylon rode with a covered Amsteel leader tick all of the required boxes?

I also would not use this rig for a primary or around rocks. Only V or kedge, and only sand and mud. Chain is for rocks.
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Old 19-03-2017, 07:56   #10
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

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Originally Posted by geoleo View Post
Generally speaking-no anchor will work without a chain!
I am not sure if you made this statement seriously, but it is not a silly concept.

In anything other than deep anchorages, with higher wind forces, chain catenary only has a very slight effect on an anchor's holding ability.

However, chain weight does help in the initial stages of setting anchor. On many modern anchors it also helps force the anchor to adopt the correct setting position.

This is an example of an anchor not sitting in the ideal setting position. If we apply a little force the anchor will (hopefully) fall over and adopt a better setting position. The chain weight is adding to instability and will help the anchor to achieve the optimum position. However, as the anchor digs in the same weight reduces the anchor's ability to rotate upright. Dyneema would have no such effect. Would this make a practical difference?




Anchor designers develop their designs to work optimally with some chain weight. I think we need some experimentation before using anchors with no chain in critical applications. I suspect the effect will vary with different anchor designs and substrates.

A small section of chain removes most of these concerns, but reduces some of the advantages of a lightweight aluminium anchor.
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Old 19-03-2017, 08:16   #11
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

When I say kedging I mean placing an anchor to the side of a grounded boat to create some heal to help free her. For that I want minimum stretch but strength in the rode. I also want my rode to be easy to tie a bowline as I generally attach it to a halyard. No need for hardware because the need is drop, pull and remove over a short time. That makes the ideal kedge set up very different from the normal anchor. However, as I don't plan to ground my boat very often my spare anchor is set up as a backup anchor not a kedge. Thus some chain, shackle and nylon rode.
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Old 19-03-2017, 08:42   #12
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

I would have thought that "stretchy" rode is better.
We live off-road and I regularly pull vehicles out of the ditch, a stretchy line is much better for both the vehicles (breaking parts) but more importantly for getting the vehicle out. It's the bungee approach, on a boat it would keep tension on the line so wave action could help move the boat in addition to the straight pulling effort

Bill


, length of dyneema,
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Old 19-03-2017, 09:13   #13
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

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I would have thought that "stretchy" rode is better.
We live off-road and I regularly pull vehicles out of the ditch, a stretchy line is much better for both the vehicles (breaking parts) but more importantly for getting the vehicle out. It's the bungee approach, on a boat it would keep tension on the line so wave action could help move the boat in addition to the straight pulling effort

Bill


, length of dyneema,
If you want to use the stored momentum, yes, if steady pressure, not so much.The anchor will move in the bottom and a polyester rode will stretch a few percent. Nylon, on the other hand, takes a lot of energy to get tight, and when breaking a boat loose, you want some of those higher force bumps. Dyneema, though, is probably too low stretch.

But there is not one answer.
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Old 19-03-2017, 09:17   #14
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

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If the word "kedge" means the anchor on the stern that is carried out in the dinghy to recover from navigational mistakes...blah, blah, blah
Getting a little off topic, but...

You can also use a kedge off the bow to pull yourself along on windless days. We used to do this on a brigantine...we called it "kedging". Useful for getting the last little bit into a protected anchorage when your boat has no motor. I think Joshua Slocum wrote of using this technique on his famous trip as well.
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Old 19-03-2017, 09:28   #15
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Re: Kedge Anchor with no chain and Spectra Dyneema rode.

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Originally Posted by Dave22q View Post
When I say kedging I mean placing an anchor to the side of a grounded boat to create some heal to help free her. For that I want minimum stretch but strength in the rode. I also want my rode to be easy to tie a bowline as I generally attach it to a halyard. No need for hardware because the need is drop, pull and remove over a short time. That makes the ideal kedge set up very different from the normal anchor. However, as I don't plan to ground my boat very often my spare anchor is set up as a backup anchor not a kedge. Thus some chain, shackle and nylon rode.
I'm not sure what you call it when you take an anchor from a halyard to drag yourself off a shoal...but I wouldn't call it kedging.

And I would want some stretch in that line...otherwise the shock (when force suddenly applied) could damage any of the hardware in between...which is your mast, stays, turnbuckles, cleats, etc.
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