Two anchors, one rode - best practice?

[thinwater]

Originally Posted by boatpoker

- Both anchors set
- rode tension roughly equal
- scope approx 9:1
- 35lb. Bruce + 35lb. Delta

The difference between this and in-line is that the first anchor does NOT have the second pulling on its tail.

I wonder if a short rode (10'?) on the slide anchor would be even better.

[thinwater]

Originally Posted by boatpoker

- Both anchors set
- rode tension roughly equal
- scope approx 9:1
- 35lb. Bruce on primary, all chain
- 35lb. delta on 50' chain and 3/4" Nylon rode

With a horizontal windlass with wildcat and gypsy it's a simple matter of hauling in the secondary to the carabiner, unclipping the carabiner, completing the haul in and then retrieve the primary as normal.

What were the rode materials? It seems like they would need to have similar stretch, ruling out nylon for the slider. Polyester or Dyneema could work. You don't really need weight or cut resistance.

[boatpoker]

Originally Posted by thinwater

The difference between this and in-line is that the first anchor does NOT have the second pulling on its tail.

I wonder if a short rode (10'?) on the slide anchor would be even better.

perhaps but 65mph winds and waves breaking over the pilothouse .... it worked !

I think stick with that in severe condition until it doesn't work

[Mycroft]

I use a 10ft "rode" connecting the second anchor Tom. Did you read the post I made earlier in the thread?

Originally Posted by thinwater

The difference between this and in-line is that the first anchor does NOT have the second pulling on its tail.

I wonder if a short rode (10'?) on the slide anchor would be even better.

[thinwater]

Originally Posted by boatpoker

perhaps but 65mph winds and waves breaking over the pilothouse .... it worked !

I think stick with that in severe condition until it doesn't work

Come on! You tried something innovative and it worked. Don't become a old curmudgeon now!

[thinwater]

^^ Unless I'm reading this wrong, when there is a >90 degree shift, the slider carabiner becomes a pulley, greatly increasing the force on the slider anchor. This will cause the new anchor to drag into the original anchor, fouling them both. Rigged as Mycroft suggests (V-tandem with a short side rode--I do something very similar) this cannot happen.

Rock climbers sometimes connect anchors in this manner, and it is considered poor practice if the load is from an angle, because of the force multiplier.

Perhaps you have not experienced this; it would require a big shift, big wind, and poor holding.

I think this is a trick for storms where a big shift is not expected.

[boatpoker]

Originally Posted by thinwater

^^ Unless I'm reading this wrong, when there is a >90 degree shift, the slider carabiner becomes a pulley, greatly increasing the force on the slider anchor. This will cause the new anchor to drag into the original anchor, fouling them both. Rigged as Mycroft suggests (V-tandem with a short side rode--I do something very similar) this cannot happen.

Rock climbers sometimes connect anchors in this manner, and it is considered poor practice if the load is from an angle, because of the force multiplier.

Perhaps you have not experienced this; it would require a big shift, big wind, and poor holding.

I think this is a trick for storms where a big shift is not expected.

how about .... with a 90 degree shift, the secondary becomes the primary and if that lets go you still have the original primary holding.

[thinwater]

Originally Posted by boatpoker

how about .... with a 90 degree shift, the secondary becomes the primary and if that lets go you still have the original primary holding.

However, if there is ANY tension on the main rode, the slider anchor will need to rotate to face that as well, and that will also place additional pressure on the slider anchor.

It just seems to me there is no special advantage over simply attaching the second anchor to the rode, and several disadvantages.

[boatpoker]

Originally Posted by thinwater

However, if there is ANY tension on the main rode, the slider anchor will need to rotate to face that as well, and that will also place additional pressure on the slider anchor.

It just seems to me there is no special advantage over simply attaching the second anchor to the rode, and several disadvantages.

Perhaps one significant advantage is the very easy retrieval of both anchors but despite online theories It worked so I'll keep it in my arsenal.

It may work in theory but it won't work in practice or the reverse if you choose

In a 90 degree shift the the slider would turn 90 degrees first and in so doing becomes the primary.

[meirriba]

Originally Posted by Jim Cate

So, re your first question above: The same issue exists if you have two smaller anchors deployed on one rode... if the windlass fails, you still have to hoist around the same mass, and it is complicated by the joining of the second anchor. The usual method for such situations (failed windlass) is a long line with a chain hook, lead back to a cockpit winch. It is a PITA, but it works, and the difference between doing it for a 25 kg and a 45 kg anchor would not be so great. That additional weight is about the same as an additional 20 feet of 10 mm chain and most of us would not worry so much about that.

MY biggest concern about your proposed method is when there is an unexpected storm or other need for greater holding power. For your tandem method, you must either weigh anchor and then wrestle the second anchor and chain into position and shackle them together and then somehow reset the lot, or perhaps just shackle on the second anchor and veer a lot of additional chain.. if there is enough left in the locker.

Somehow just having your big anchor set in all situations, ready for whatever conditions arise with no further action needed... well, it just seems better to me. And, FWIW, to most of the long term cruisers we know as well... the guys who have experienced the unexpected storm at 0200 a few times!

Your boat, your choice of course...

Jim

I believe that we have some misunderstanding.
It is clear that the main anchor should be adequate and even 'oversized' and not some puny hook that will drag when the wind raises to 30-40 knots.
But, and here is the main issue that caused this thread from me, is the question - do I have to be prepared for a hurricane every day and carry a double sized anchor at all times?
As to your comment about windlass failure: I beg to differ. When the windlass fails, and I use on day to day basis a 'normal' slightly oversized anchor, it will be a different story than having to raise manually an anchor twice the normal size. Your logic that it is the same, applies only if the windlass fails concurrently with the deployment of two anchors in a exceptional weather. The probability of this is much lower.
BTW - I did raise manually for a week in Tonga and a week in Turkey - both times anchors in 25Kg range, using different methods, including the halyard you suggest. I am not sure that the experience would be pleasant with lets sat 45kg one.
Anyway - I have started this thread to learn, and I keep in mind all comments. Never stated that tandem anchoring is my preferred tactic!

[brianlara 3]

Originally Posted by brianlara 3

Simple. My humungous 35lb supreme & 250ft of 5/16 chain is on the bow. The ordinary 25lb supreme sits on a stern roller with 26ft of 3/8 chain and 100 ft of rode.
If i need to anchor in, say, 60 ft of water and 50 knots, I'll shackle the sterner and chain to the front of the bower.....& then relax.
When the bower is back in the roller I can still reach the 3/8 chain and drag the little one back on board. Haven't tried it in anger get, don't need to.
The sterner's there so why not use it when off a cliff face in deep water on a lee shore.
Sure, going to be rough as hell but beats having massive salvage costs and loss of everything.
Why not?

Coincidentally.....
Pulled the lot up today from 65ft of water in Middle Harbour off Quakers Hat (Sydney). Was down for two days gusting 40. Didn't budge.
The only bad part was the front chain was packed with black mud.
Am now confident that 70 knots in 50 ft would be fine.

[meirriba]

Originally Posted by Mycroft

I'm going to offer an alternate view from most in this thread.

Roger Hughes' article "Anchoring Once and For All" in the Jan/Feb 2016 issue of Good Old Boat magazine had a great method of using a second anchor. I had just begun my Pacific Northwest cruise and ran into some seriously sketchy and DEEP, rocky anchorages where that second anchor really added some serious piece of mind.

My primary anchor is a Rochna 33, while my old CQR 68 is now my secondary. My rode is a 300ft 7/16" chain. Using Hughes' article as a guide, here's my procedure.

If the anchorage is deep, say 90ft, I'll lower the primary until it hits the bottom and then adde a few more feet of chain. Then I'll connect my secondary to the chain with a short 10ft rope rode and a shackle. (The secondary has a second 25ft rope attached that I'll get to.)

Once the secondary is attached to the chain, then I'll let out the rest of the rode.

In such a deep anchorage as this, at best both anchors dig in and my swing is reduced. At worst, the second anchor lifts and acts like a kedge of sorts. (Of course at truly worst, all 140 lbs of anchors would lift and I would be blown into the rocks.)

Compared with tandem (which I didn't even bother to attempt), retrieval is not that much more difficult than a single anchor. Here are my steps:

I pull the chain until the shackle of the secondary is on deck. Then I reach down with a boat hook to grab the second rope rode on the anchor and run it up my secondary roller to the capstan. (We're still held in place by the primary anchor at this point.) After I pull the secondary up to it's holding spot, I unshackle it from the chain and pull up the primary like normal.

Even if the depth of the anchorage isn't that deep, I'll frequently drop the secondary if the bottom is rocky (like so many up here in PNW fiords).

I hope this helps answer your question Mark.

Bob

Thanks!

[meirriba]

Originally Posted by boatpoker

I have used this in a tropical storm anchored with breaking waves hitting the pilot house. The primary rode runs freely through a large stainless steel carabiner on the second anchor and there was about 50' between anchors. It was very easy to retrieve. I'd do it again.

Theoretical question, as it is a novel idea for me.
You have written in a following post that both anchors are set in the ground.
It seems to me, that if the wind is strong enough, it will straighten the catenary of the primary chain and this will in effect lift the secondary anchor off the ground (unless both anchors are very close to each other, unlike the picture).

[boatpoker]

Originally Posted by meirriba

Theoretical question, as it is a novel idea for me.
You have written in a following post that both anchors are set in the ground.
It seems to me, that if the wind is strong enough, it will straighten the catenary of the primary chain and this will in effect lift the secondary anchor off the ground (unless both anchors are very close to each other, unlike the picture).

anchors are about 50' apart. If the secondary pulls out it still acts as a huge kellet.