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Old 29-05-2014, 01:33   #31
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Re: The Delta failed us again.

The Delta is a good (not great) anchor.
It does have a couple of weakness that limit its performance.

In very soft substrates the convex blade design does not provide a lot of resistance. Some substrates do firm up sufficiently with depth to overcome the problem, but others remain too soft, even if the anchor dives deeply, for the limited drag coefficient of this sort of shaped anchor to do well.

The second problem with the Delta is that it needs a good scope. All anchors have a much higher holding power at a longer scope, but some anchors are particularly vulnerable to a short scope and the Delta is one of these.

I don't know the area concerned, but it sounds like you managed to inadvertently combine both of the weakness together with a reasonably small sized anchor and the complication of stern anchor (with any crosswind this leads to higher forces)

The highest holding power of any anchor in the substrate you describe is the Fortress, but any of the concave roll bar anchors or the steel Spade would give you much better performance. These anchor are very versatile doing most things well.

It sounds like a change might save the marriage and the boat.
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Old 29-05-2014, 01:35   #32
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Re: The Delta failed us again.

Quote:
Originally Posted by noelex 77 View Post
The Delta is a good (not great) anchor.
It does have a couple of weakness that limit its performance.

In very soft substrates the convex blade design does not provide a lot of resistance. Some substrates do firm up sufficiently with depth to overcome the problem, but others remain too soft, even if the anchor dives deeply, for the limited drag coefficient of this sort of shaped anchor to do well.

The second problem with the Delta is that it needs a good scope. All anchors have a much higher holding power at a longer scope, but some anchors are particularly vulnerable to a short scope and the Delta is one of these.

I don't know the area concerned, but it sounds like you managed to inadvertently combine both of the weakness together with a reasonably small sized anchor and the complication of stern anchor (with any crosswind this leads to higher forces)

The highest holding power of any anchor in the substrate you describe is the Fortress, but any of the concave roll bar anchors or the steel Spade would give you much better performance. These anchor are very versatile doing most things well.
As will the Excel. I have anchored many times in the same location on the same boat with Delta and with Excel (and Rocna and Manson Supreme) and the Excel
is light years ahead of the delta and has similar or better performance to the Supreme and Rocna. If I didn't have the Excel I would use a Manson Supreme (note however - I have never owned or used a Mantus on my boat)
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Old 29-05-2014, 02:58   #33
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Re: The Delta failed us again.

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As will the Excel. I have anchored many times in the same location on the same boat with Delta and with Excel (and Rocna and Manson Supreme) and the Excel
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And yes I have owned a Rocna, a supreme a delta, a bruce, and many many cqrs.
It would be great to get some more details of the strengths and weaknesses of these anchors from your experience. Very few people have owned three different types of new generation anchors and used them on the same boat.

You do briefly mention the Manson Supreme in your blog when discussing the selection of the anchor for your current Seawind 1000XL:

"Boat came with a 35lb Manson Plough (a CQR style) on 50 meters of 8 mm chain (with a Muir Storm electric anchor winch). The anchor never dragged but it was ambivalent about setting. So after much research and head scratching I have decided on a Sarca Excel. Whilst I think the Manson Supreme would have been a fine replacement, the way the anchor comes up through the deck meant that an anchor without a roll bar was the better way to go."

If you bought an Excel and it worked well why did you subsequently buy the Rocna and Manson Supreme anchors for your Seawind? Or did you own a prior Seawind with a Rocna and a Manson Supreme? Or were these just anchors on boats from your dealership?

(I send you an Anchorholicis Anonymous membership form, anyway )
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Old 29-05-2014, 03:53   #34
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Re: The Delta failed us again.

my 'theory' with bow and stern anchoring is that
If you are anchored bow only and the wind/currents change, the pull on the anchor is lets say
10k wind - 1 tonne pull
20k wind - 2 tonne pull
however anchoring bow and stern = additional side forces - windage, wetted surface, not to mention the leverage action
so assuming 10k now = 2 tonne pull laterally, add to that the leverage gained from the dynamics and the pull on the anchor is now 4 tonne in 10k on the beam
Also 5:1 scope minimum is space permits.
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Old 29-05-2014, 04:11   #35
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Re: The Delta failed us again.

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Originally Posted by noelex 77 View Post
If you bought an Excel and it worked well why did you subsequently buy the Rocna and Manson Supreme anchors for your Seawind? Or did you own a prior Seawind with a Rocna and a Manson Supreme? Or were these just anchors on boats from your dealership?
I have to wonder - why the cross examination. Why the sensitivity? That Para above was written fairly early in the life of the boat.

Anyway - Firstly - no they were all anchors on my boat. Anchors I bought, paid for and used, and in the case of the Rocna and Supreme, sold. And of course the Delta - which I actually got really really cheap off a guy who bought a new mono with it on - which I donated to a young fellow who had a ball of rust on an RL 28 pretending to be an anchor. . I still have the Manson CQR under the house. No one will buy it.

Why did I buy the Rocna and Supreme, well people kept telling me they were the greatest thing since sliced bread, and many of my clients had also been convinced, so I tried them, really its a bit important in my line to actually speak from an informed position. The excel was still the best solution, the Rocna and Supreme were good but no better than the Excel, and suffered, particularly the Rocna, from clogging and resetting in a tidal shift (Brisbane River - Town Reach), even though you say that it doesn't happen, it did for me. The Manson Supreme had a similar behaviour - less so, but it was in a different location (St Helena Island in Moreton Bay). So the excel resets better and fits the anchor roller system better. That fact that it is Australian made was also a good thing. The Mantus with its roll bar removed might be okay from a fit point of view, as Mantus do suggest the anchor is fine with the roll bar removed, but I worry about any concave anchors resetting, however with the roll bar off that might be less of an issue and the Manson Boss could be worth a shot - but I have spent enough on anchors now so experimenting with the Mantus etc will have to wait.

Let me be clear - The Rocna and the Supreme are fine anchors, but I have had both clog and have difficulty resetting, the Excel is equally as good and being convex doesn't clog. The Delta was actually pretty good, but not as good as the others, the Manson CQR was actually also okay , once it set, which was always a bit of an effort. I have no experience with Mantus.

I would always choose a Manson Supreme over a Rocna as they both work equally well but Manson as a company does not have the baggage of Rocna, in short I know I can trust them to back up their product and indeed they have a very very positive reputation.

Anything else on that blog (that I had very nearly forgotten about) that I need to justify. Your viewing of my blog doubled its numbers for the month, thanks.
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Old 29-05-2014, 04:47   #36
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Re: The Delta failed us again.

We sold our Delta in Panama to some unlucky bloke.

I still feel guilty about that.
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Old 29-05-2014, 04:50   #37
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Re: The Delta failed us again.

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We sold our Delta in Panama to some unlucky bloke.

I still feel guilty about that.
I am sure you needed the money for important stuff, like rum.
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Old 29-05-2014, 04:58   #38
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Re: The Delta failed us again.

There are three different issues here: (1) choice of anchor; (2) size of anchor; and (3) technique. Choice of anchors is a classical theme on this Forum, so I won’t go into that much – you can read about it til you puke in the archives. People have strong views, let’s put it that way.

As to technique: Without good technique, it doesn’t much matter what anchor you have. First of all, if your anchor is not holding in soft bottom, that fact should be revealed while you’re setting it, not the night after. Especially if you’re anchoring in a mud bottom, you should always back down hard and long after the anchor has been set to be sure that it’s not creeping through the mud. The classical way to tell is by looking at transits, but I personally find the chart plotter even better. Set at maximum scale, and with “tracks” enabled, you see very well whether you’re solidly anchored or whether you’re creeping through the mud. Any SOG with COG astern proves you’re creeping, and you will be able to see your track. 0.00 SOG, or a little SOG with COG in an arc around the anchor, shows that you’re well set.


The other thing is scope. As others have pointed out, 3:1 is not enough for shallow water. In less than 25 feet of water, I would not personally use less than 5:1, or better 6:1 or more is there is swinging room. Don’t forget to add the height of your bow roller to the depth. For me, 5:1 in 12 feet of water would require 12 + 5 = 17 feet * 5 = 85 feet of chain, since my bow roller is about 5 feet above the water.


As to size: As other have pointed out, your anchor is undersized according to what we understand today. My boat was delivered with a 25kg Delta, so I’ve been exactly in your position. I never dragged my Delta (probably because I would always pull it up again on the frequent occasions when it didn’t withstand a full power pull in reverse for 5 minutes), but I very often couldn’t get it to set, even in bottoms which shouldn’t have been that difficult.


I went from that to a 55kg Rocna (more than twice the size of the Delta; 121 pounds), which set and held much better. But the big Rocna also had difficulty getting a good set in soft mud, so I had a few cases of having to set and reset it numerous times before I was satisfied.


I replaced the Rocna with a 100 pound Spade, which works much better than the Rocna. The Spade has a very sharp, triangular fluke, and is ballasted with lead. The lead ballast makes it sink into soft mud faster, sinking down to a usable substrate more reliably.


Those are my personal experiences on the “choice of anchor” question; as I said, you can find a lot of different opinions in the archives. Since you should be increasing the size of your anchor anyway (probably double), you will probably have a chance to choose a different type. You will have fun researching the pros and cons of the various choices!



Good luck!
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Old 29-05-2014, 05:02   #39
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Re: The Delta failed us again.

Quote:
Originally Posted by monte
my 'theory' with bow and stern anchoring is that
If you are anchored bow only and the wind/currents change, the pull on the anchor is lets say
10k wind - 1 tonne pull
20k wind - 2 tonne pull ...
FWIW:
Wind force varies as the square of the velocity, hence:
10k wind = X pull
20k wind - 4X pull (NOT 2X)
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Old 29-05-2014, 05:06   #40
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Re: The Delta Failed us Again.

Our primary anchor is a 55 lb delta. It is not very dependable in very soft mud/silt. It is difficult to set and I've had to use as much as 8 to 1 scope in soft mud and even then have dragged a few times (all chain). Only once did it actually break out, the rest of the incidents were more like it slowly plowed through the mud. I've never had a problem in consolidated mud or sand. I never use less than 5 to 1 no matter what the bottom is like. I'm not surprised that with a 3 to 1 scope in mud that it didn't hold. Since you titled the thread "the delta failed us again" it would seem that you have had this experience before, so why were your surprised??
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Old 29-05-2014, 05:11   #41
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Re: The Delta failed us again.

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Originally Posted by S/V Alchemy View Post
I have never used less than 5:1, even in lunch hook/90 minutes stopping situations.
I don't know if you ever anchor in deeper water, but by the time you get to 15 or 20 meters depth, I think 3:1 is fine.

In the English Channel, where the tidal range can be more than 10 meters (33 feet), you can often find yourself in 20 meters of water at high water after anchoring in something much less at low water.

In that kind of water, I typically just put out my whole chain (100 meters or 330 feet of 12mm), but if there's not enough swing room for that, 3:1 is really ok.
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Old 29-05-2014, 05:12   #42
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Re: The Delta Failed us Again.

We always had good luck with the Delta. But then again we always had a Danforth hanging of the bow as well. Were the Delta wouldn't set, usually mud, the Danforth would. Never rely on one anchor as there isn't one anchor made that holds well in all bottoms. And 3:1 scope
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Old 29-05-2014, 05:12   #43
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Re: The Delta failed us again.

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Originally Posted by Dockhead View Post
you will probably have a chance to choose a different type. You will have fun researching the pros and cons of the various choices!
I bet the fun part for most of us ends once we come to realize that anchor opinions are like a**holes, except lots of people have more than 1 anchor opinion.


But seriously now lets admit it, anchor threads are mostly about entertainment
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Old 29-05-2014, 05:27   #44
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Re: The Delta Failed us Again.

As Capt. Herreshoff noted. I don't trust anchors that look like they would also be comfortable being towed behind a tractor in a field.
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Old 29-05-2014, 05:28   #45
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Re: The Delta Failed us Again.

Something that should be taken into consideration, Delta anchors, when we released our Sarca anchor some twenty years back, Simson and Laurence launched the Delta, I am fortunate enough to still have my origional test Delta from Simson and Laurence.

When Robertsons anchor testing took place they supplied a Delta themselves only now they were all made in China, when comparing-- the origional Delta had a thinner shank and was a much harder steel as to the China produced unit from Robertsons.

Performance was chalk and cheese, and yes the origional Delta in soft mud matched against the Rocna or Supreme was an absolute eye opener in diving and holding power where as the one produced in China was a far cry from the origional.
This may well explain why some swear by them and others dont.

Regards Rex.
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