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Old 28-03-2013, 06:03   #121
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Re: Anchor design and misnomers

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Originally Posted by Andrew Troup View Post
imagine that grader blade with an array of smallish holes through it, grading deep, sloppy mud. I reckon that would actually take more horsepower after your drilled the holes than before.
I like this theory, maybe I need to get out my drill and test it on my old plow!

Maybe thats an advantage to the danforth slot and the new english anchor with the slot down the middle.

Another thought is that it is something to do with the drained vs undrained sheer strength. The slots might help the soil drain when under presure. then again they may do nothing.

But I'm also completely thinking out loud here: I have NO expertise in this field.
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Old 28-03-2013, 06:27   #122
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Re: Anchor design and misnomers

SnowP

I just struggled through the Excel patent, and either we're onto something, or Rex is not.

He explicitly describes the purpose of the multiple slots in the Excel flukes as being to pass water.

HOWEVER: he comes to a rather different conclusion from me as to why this is beneficial, which has me scratching my head, but the chances of me having it right and him wrong seem vanishingly low. It is however possible we're both right, because our explanations are possibly not mutually exclusive. He says it's to reduce the friction of the mud on the fluke, by relieving the pressure buildup - which I sort of get. Not yet convinced, though.
He seems to be saying he wants the mud to flow along the fluke, rather than stick to it, so the anchor can set deeper. I sort of get that, but I'm not certain I can be confident the slots would achieve that... I'd have thought the drier mud might get stickier.

Still, at least we know it's not intended as a cheese grater!

Where his explanation tallies exactly with mine is around what I call the 'spoilers' - except he points out that their 3D orientation promotes the rear of the anchor digging deeper (once again, I imagine that could be too much of a good thing, if the angle was excessive, causing the anchor to pitch nose-up and start climbing back out....)

I guess another crude analogy for them is the chipbreaker on a lathe tool insert.

BTW: About Jacques' twin Very Big Danforths in the hawses - your recollection is accurate. It seemed extraordinary to me, too...
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Old 28-03-2013, 06:57   #123
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Re: Anchor design and misnomers

A long, and I must admit very thoughtful post of mine, has disappeared somewhere in the Intertubes. Shorter me: it still seems to me that yacht anchor design is closer to art than science, and there are so many variables that it is very hard to balance all of them in such a way that you make a major advance.
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Old 28-03-2013, 07:43   #124
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Re: Anchor design and misnomers

Good thread so far.

I also am hoping for clarity on the best new gen anchor available in US, without rollbar (which IMHO is wasted weight that doesn't affect holding, can hinder resetting by trapping seabed, and is a PITA on anchor rollers)

If the excel lives up to the hyper- sounds great.

Trouble is, the one size fits all may be tough-
for example, on the Chesapeake, fluke anchors (danforth/fortress) often hold best because bottom is soupy and surface area rules. However, in the dwindling areas where there is grass (eg St Marys) I have found on someone else's boat that you can't get a fortress through, but a delta sets immediately. I have slowly dragged a bruce in squalls through mud, but had it set easier than the danforth in a firmer bottom.
That's the problem- to penetrate a firm bottom, you need sharper and smaller blades. To hold in a looser bottom, broad flat blades are the best.



(And no one yet has come up with an anchor that lets you anchor in the middle of Great Harbor in Jost Yan Dyke, BVI- where there is that area of boilerplate rock! If so, every charter boat needs to be equipped with that type so they don't drag after lowering anchor and immediately dinghying in to foxys. )
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Old 28-03-2013, 08:00   #125
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Cotemar Helix Anchor

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Seems to me that yacht anchor design is closer to art than science, and there are so many variables that it is very hard to balance all of them in such a way that you make a major advance.
The next big evolution in anchoring will be a Cotemar Helix Anchor that automatically drops down from the bow or mast base and screws itself deeply into the seabed.

1) More boats would be able to safely anchor in a harbor

2) Your anchor circle would only be your boats length

3) The Cotemar Helix Anchor would secure your boat to a depth and with the holding force that no modern day anchor can come close to matching.

4) It will work by electric hydraulics with telescoping square tubing projecting down to and then into the seabed

5) It gets even better. As an option, if you want to check on the status of your Cotemar Helix Anchor, instead of diving on it to check its status, you simply send down a seabed camera to your Helix Anchor and watch the surrounding aquatic sea life from your iPad or large flat screen monitor. Safety and entertainment, all in one.

6) Patent Pending

Stay tuned, you never know who you will meet in these Cruisers Forums
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Old 28-03-2013, 09:05   #126
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Re: Anchor design and misnomers

[QUOTE=malbert73;1196692]

I also am hoping for clarity on the best new gen anchor available in US, without rollbar (which IMHO is wasted weight that doesn't affect holding, can hinder resetting by trapping seabed, and is a PITA on anchor rollers)
[\quote]

My take right now:

(Lead) Weighted tips:
Spade
Ultra

Unweighted tip:
Boss
Ray/Bruce

(Steel) weighted tips:
Delta (and various derivatives)
Excel
------------
In concept, right now, I like the ultra. But have not yet seen much solid data on its performance. And it is expensive.

The spade is good but I don't like that you have to melt the lead out to regalvanize.

I suspect the Boss is excellent in good sand/mud penetrating bottoms, but am a little worried they optimized it a bit too much for "good" bottoms, and not enough for the bad 1% situations that I really care about.

The Ray is my bow anchor choice right now, with all the well known strengths and weaknesses if the Bruce type. Sort of the opposite if the Boss? You have to care about performance in the 1% worst bottoms more than getting the last bit of holding power in good bottoms.

Delta, good cheap general purpose anchor. Sort of the "minimum benchmark" these days. Can in fact be made to work most places with proper size, Rode, scope and some skill.

Excel, don't know yet.
--------------------
Here's a question for the group re the above thoughts . . . . Here are holding power or two anchors. I know which one I choose. Which would you choose?

Holding 95% of time in typical sand/Mud.
Anchor R= 2000kg.
Anchor B= 1000kg

Holding 5% of Time in worst Most difficult bottoms
Anchor R= 100kg.
Anchor B=1000kg
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Old 28-03-2013, 09:59   #127
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Re: Anchor design and misnomers

I'd take anchor R for use 95% of the time and either use a second anchor or switch to a specialty main anchor for oddball 5% of the time anchorages.
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Old 28-03-2013, 10:12   #128
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Re: Anchor design and misnomers

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Hoho! No, Stu, I just want a third anchor to complement the MS and Fortress, in case I lose one or have to leave somewhere in a hurry. Very happy at the moment, but figure if I get a third it has to be different from the other two.
So totally agree, my wife Vivien usually handles the anchoring, if as we back up slowly she has to stop herself falling forward we both smile knowing the pick is set....

We have all chain, a swivel with a 35kg KOBRA it rarely misses to set within a metre of being dragged and has nicely held in 60+ knots...

Repetitivous Technique is the secret.....

Cheers
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Old 28-03-2013, 10:21   #129
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Re: Anchor design and misnomers

Quote:
Here's a question for the group re the above thoughts . . . . Here are holding power or two anchors. I know which one I choose. Which would you choose?

Holding 95% of time in typical sand/Mud.
Anchor R= 2000kg.
Anchor B= 1000kg

Holding 5% of Time in worst Most difficult bottoms
Anchor R= 100kg.
Anchor B=1000kg
It used to be standard recommended practice for world cruisers to carry a quiver of various anchors for use in different bottoms, and I think that idea still has merit.
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Old 28-03-2013, 11:31   #130
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Re: Anchor design and misnomers

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I'd take anchor R for use 95% of the time and either use a second anchor or switch to a specialty main anchor for oddball 5% of the time anchorages.
K, the problem is that usually you don't know you are in the 5% until it's 2am and the wind is up and you start dragging. Usually you thought you set the anchor and that it was fine.

So, sure it's not difficult if you always had perfect information on the bottom but usually (out if the tropics) we do not.

And even if you do somehow have perfect information on the bottom, it's still a relevant question . . . How often do you want to pull another anchor out vs just dropping the main?
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Old 28-03-2013, 14:49   #131
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Re: Anchor design and misnomers

[QUOTE=Snowpetrel;1196597

Maybe thats an advantage to the danforth slot and the new english anchor with the slot down the middle.


[/QUOTE]

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Old 28-03-2013, 14:59   #132
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Re: Anchor design and misnomers

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So, sure it's not difficult if you always had perfect information on the bottom but usually (out if the tropics) we do not.

And even if you do somehow have perfect information on the bottom, it's still a relevant question . . . How often do you want to pull another anchor out vs just dropping the main?
It's true you don't know what is down there, but I have found that I almost always get a pretty good idea between the charts, the cruising guide, and what happens when I back down. It is pretty rare, though it has happened, that I can't tell if I've got a good hold. Since I set the anchor by hand for the initial pull I can get a pretty good feel what the bottom consistency is like. If I'm in a rocky cove and I feel grinding through the chain I can guess that it is pretty hard. You can also feel this in how it sets when you back down. If it catches, releases, then catches it could very well be one of those very hard sand bottoms you find in the Caribbean, and apparently the Med. according to Noelex. There is a certain, satisfying give and then gradual build in holding with a decent mud or sand bottom, and then when I crank up the power with my big three-bladed prop I can put significant load on there.

As to your second point, I think your original premise is somewhat biased towards getting the answer you want. What if in 95% of the harbors anchor R was only 1500, but in 5% it was more like half that or 750? I'd rather drop two 750s if needed for the occasional 5% situation.

Bottom line is these numbers are very theoretical, so there is no right answer.
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Old 28-03-2013, 15:13   #133
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Re: Anchor design and misnomers

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Bottom line is these numbers are very theoretical, so there is no right answer.
Well I have pretty good reason to believe that my rocna had sonewhat better holding power 95% of the time but much less good holding 5% of the time than the Ray. .... The holding numbers are obviously not exact and its obviously a more complex probability than just binary, but it draws the picture. So, for me it is in fact a real and practical question.

Most anchor tests seem to assume the answer is obvious and you should take anchor R. I choose anchor B. It's exactly why I tested anchors in difficult bottoms rather than normal/typical ones. I was just curious how other people would choose.

I guess you are saying you would take both and put anchor R on your Bow, and dig out anchor B at 2am if you had to.
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Old 28-03-2013, 15:23   #134
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Re: Anchor design and misnomers

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I guess you are saying you would take both and put anchor R on your Bow, and dig out anchor B at 2am if you had to.
I would have already set anchor B or a second anchor of some sort from the get-go if I felt the holding was iffy or the weather might turn bad for some reason. Maybe it is very deceptive where you have been, but I can only recall less than a handful of times when I dragged and I thought I had a good hold. My current boat has a powerful engine, and if I back down hard on the anchor I'm good--at least so far--never dragged with the current boat, but I frequently put out a second anchor if I'm uncertain about things, or I am anticipating possible wind shifts.
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Old 28-03-2013, 15:30   #135
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Re: Anchor design and misnomers

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Well I have pretty good reason to believe that my rocna had sonewhat better holding power 95% of the time but much less good holding 5% of the time than the Ray. .... The holding numbers are obviously not exact and its obviously a more complex probability than just binary, but it draws the picture. So, for me it is in fact a real and practical question.

Most anchor tests seem to assume the answer is obvious and you should take anchor R. I choose anchor B. It's exactly why I tested anchors in difficult bottoms rather than normal/typical ones. I was just curious how other people would choose.

I guess you are saying you would take both and put anchor R on your Bow, and dig out anchor B at 2am if you had to.
If both anchors weigh 25kg its really not a big issue to pull the second one out of the locker. If they both weigh 50 kg it is a big issue. Because its not a big issue to have one sitting on the bow, rode attached, ready is simply prudent and actually not difficult to deploy. If you had 50kg anchors then 2 bow rollers seems sensible and then you just press a button to pull one up and another button to drop the other one down (that's why we now have electric winches.

If lifting and resetting anchors is such aggravation - possibly you need a new lifestyle. It happens.

It seems sensible to have backed the first anchor in at full revs in the first place.

The thing I have not got my head around is the BIB set who only have one monster anchor, what do they do in your scenario. The 'Small is Adequate' minority have Kettlewell's quiver - but when R does not set (in your scenario) they are embarrassed? Maybe if they lived
'down under' they would have option E

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