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**GordMay** · 22-10-2006, 01:44

I’m reminded of an excellent theoretical treatise
“Tuning an Anchor Rode” ~ by Alain Fraysee
http://alain.fraysse.free.fr/sail/rode/rode.htm

craigsmith · 22-10-2006, 02:33

Quote:

Originally Posted by Alain d'HYLAS

But are we talking about the same thing?? To my great surprise, I did not find nowhere the graph very favorable to Rocna, published by C.Rocna. There are some others...

For information purposes, I join the one of the page 68: "Effect of Location on holding power":

- In two places out of the three, the results of the Rocna is good and average in the third:
- at "East of warf" Rocna arrives in third position behind Fortress and Spade
- at "West of Warf" Rocna arrives in fifth position behind Fortress, Hydrobulbe, Océane and Spade
- Finally at New Brighton, Rocna arrives in third position behind Hydrobulbe and Suprème..

Then can somebody explain me how, while being respectively twice third and once fifth, Rocna can publish a figure of unknown origin, attesting that its anchor was the best in the test?

Thanks in advance for the explanation.

At the risk of getting drawn into a mud slinging competition, here is the explanation, in the form of the main chart of the article, published on the first spread (page 63):

Average figures.

Our chart is the same as this, except we use a ratio of holding power to weight in order to compensate for the differences in size (clearly one cannot fairly compare a larger anchor to a smaller anchor), and have also adjusted the aluminium anchors so as to be comparable to the much heavier steel ones.

It is consistancy which pays off, and a good test will illustrate that. Here anchors were subjected to three different conditions with three different scopes, and while some did very well on occasion, they let themselves down on others. When you are out in the real world, you do not want to be playing a guessing game when you launch your hook. You want to be able to rely on it, not worry that it happened to hold "the best" in one particular test but no others.

As such we point to the crucial "max before releasing" in the above chart.

The SAIL article should be read and studied in depth before arguing the details of the results. In actual fact the specific data for every pull is not provided. So, we are simply happy to quote averages.

Apologies to those who have seen this for the 2nd or 3rd time on as many different forums, but at the risk of sounding immature, "he started it"

**GordMay** · 22-10-2006, 03:24

Quote:

Originally Posted by craigsmith

...Our chart is the same as this, except we use a ratio of holding power to weight in order to compensate for the differences in size (clearly one cannot fairly compare a larger anchor to a smaller anchor), and have also adjusted the aluminium anchors so as to be comparable to the much heavier steel ones ...[/I]

So, how did you the adjust aluminium anchors so as to be comparable to the much heavier steel ones?

A fair comparison is important to any evaluation. I will be leery of any unspecified “adjustemts” to published (raw) data.
There might be several “fair” criteria, by which to compare anchors:
Holding power vs Retail Cost (Lbs pull - $ Dollars)
Holding power vs Weight (un-adjusted)
Tested Holding power vs Manufacturers’ Claims or Recommendations

craigsmith · 22-10-2006, 03:41

Quote:

Originally Posted by GordMay

So, how did you the adjust aluminium anchors so as to be comparable to the much heavier steel ones?

A fair comparison is important to any evaluation. I will be leery of any unspecified “adjustemts” to published (raw) data.
There might be several “fair” criteria, by which to compare anchors:
Holding power vs Retail Cost (Lbs pull - $ Dollars)
Holding power vs Weight (un-adjusted)
Tested Holding power vs Manufacturers’ Claims or Recommendations

Hi Gord,
One can adjust the "effective size" of an aluminium anchor by considering the relative densities of steel and alloy, then compensating for the fact that while increases in surface area are proportional to the square of dimensions, increases in volume (weight) are proportional to the cube of dimensions. Since it is holding power that is being tested, it is the geometrical size which matters, and comparing unadjusted results of aluminium anchors to steel on the basis of "holding power to weight" would be silly.

Your criteria suggested seem fair, although retail cost is not necessarily so, as some people prefer to spend a great deal of money on an anchor in order to secure their boat, while others will not. Consider the fact that Spade's are quite popular, although expensive - albeit not as popular as cheap Chinese-built Bruce copies. Each consumer has different values, and perceived value is subjective - as is the value of money itself!

Perhaps a letter to the editor of SAIL with your suggestions!

**GordMay** · 22-10-2006, 04:39

Quote:

Originally Posted by craigsmith

”... Since it is holding power that is being tested, it is the geometrical size which matters, and comparing unadjusted results of aluminium anchors to steel on the basis of "holding power to weight" would be silly ...” and ”... Your criteria suggested seem fair ...”

Actually, my criteria (simple ratios) were too simple. None of the desirable and undesirable characteristics should be considered in isolation (from the others).
The decision-making process (determining “value”) is a complex combination of all those stated factors (and perhaps more).
The first criteria must be (purpose):
1. Adequate holding power (more is desirable)
2. Adequate setting speed (quicker is desirable)
Additionally:
3. It has to be priced within my budgetary constraints (cheaper is desirable)
4. It has to be light enough for me & mine to handle (lighter is desirable)
5. It has to be small enough to stow (smaller is desirable)
6. et al

A better formula for determining the value of a particular anchor would look more like this:
Value = [ (Holding Power + Setting Speed) - (Weight + Size) ] / Cost

The ideal theoretical anchor would have tremendous holding power, set instantly, re-set consistently, have little mass (weight) and size, and cost “little”. I don’t have one of these.

If unequivocal holding power were the only criteria I used to select an anchor, I might choose a 10,000 Lb (or 20,000#) rock to hold my 29 Foot 6500 pound boat. I can assure you I don’t have one of these, either.

David_Old_Jersey · 22-10-2006, 07:14

Been following these Anchor discussions recently, the Rocna seems interesting. At the moment my main Anchor is a CQR (Not sure if it is a copy!)

CQR

I have not done any "serious" anchoring with this boat or anchor, and although I have not seriously dragged I suspect that this is more to do with the weight of chain used and only anchoring in good weather - certainly whenever having dried out and inspected the Anchor (one of the advantages of having an up to 40' tidal range!) that I usually have ploughed a fair old furrow in muddy sand that I have previously used a Danforth without any of sign of dragging when set. (although I have had problems of weed / debris over the years getting caught in the flukes and jamming them open - and with the anchor flpping onto it's back - so the flukes are just pointing upwards.

Danforth

I do also have on board a Bruce (might also be a copy) which I have not yet used, will probably give it a go next summer, but for me it just doesn't "look right" / capable of setting properly - obviously I am being completely unfair here as I have never even tested it AND I will admit that I know jack sh#t about anchor! - but IMO being happy with your anchor is partly also a confidence thing.

BRUCE

I also have onboard a small kedge (CQR type) which I have not yet used - be a good dinghy hook! In my backgarden I have a small Danforth Kedge which I may put onboard (fixed to the pushpit) for ease of deployement as a kedge (lunch hook?) cos I like the Anchors.

I forget the weights of both the CQR and Bruce, but they are big enough to probably give me a hernia! and IMO are big enuf for a 30' foot boat (and to some would seem to be oversize). Just that I am not entirely happy with either. As neither as fixed in a Bow Roller, I would like the next anchor to be one that was capable of doing this, but in the absence of finding something that does this I will probably go for a big Danforth on the basis that I have used them on other boats in circumstances where a dragging anchor would have meant a shipwreck 10 minutes later due to either strong currents and / or weather. And just put up with the inconveniance or put a ROCNA or the CQR on the bow roller as a "lunch hook"??? In an ideal world I would like something that was also good at re-setting itself on the basis that Anchors do break out and also something with less moving parts than a Danforth.

I would be a very happy bunny if something like the ROCNA was the answer, but I appreciate their is no "one" answer. But I am not yet convinced, I would prefer to hear from others over the next couple of years. I won't dispute the Stats, but as someone whose job does involve quite a bit of making complete b#llocks look good with Stats, I have a certain reluctance to rely solely on them!!

**Alan Wheeler** · 22-10-2006, 12:23

Well put Gord. That's exactly what I would have said ;-)
That is why I viewd the first Graph Graig supplied with scepticisim. I am not sure why anchor manufacturers worry about weight in the argument of an anchor design.
So far ALL tests I have seen have been flawed. I guess it is why there are so many on going tests. Everyone has an opinion. To me, the test should be as such.
The anchor should not be based on equal size-weight-area-or what have you. It should be based on the boat length/weight it is designed for. Then you are comparing apples to apples. When specing an anchor, this is what you choose it by. I have X long boat with Y weight. The X/Y gives you mass and windage. Then you take the anchor the manufacturer has specified for that X/Y and you go out and test its setting speed, it's re-setting speed in a 180 turn and it's holding power before release. In as many different bottom types. The holding power is my No.1 concern, the setting speed/resetting speed is No.2 in my concern book and then size/weight No.3/4 with Price being No5.
Average across bottom types is another red hearing. I want to know what anchor is best for what bottom. If one design takes in all, then it is considered more favourably to another that isn't. I don't want an average as I want to know EXACTLY if the anchor is the best choice for where I am.

craigsmith · 22-10-2006, 17:54

Quote:

Originally Posted by GordMay

A better formula for determining the value of a particular anchor would look more like this:
Value = [ (Holding Power + Setting Speed) - (Weight + Size) ] / Cost

The ideal theoretical anchor would have tremendous holding power, set instantly, re-set consistently, have little mass (weight) and size, and cost “little”. I don’t have one of these.

I agree, although there are many other factors, such as re-setting ability, ability to handle a veer without breaking out, versatility across different seabeds, consistancy of setting, construction quality, strength, durability, etc etc etc. Hence the reason no magazine test is ever perfect. So the SAIL magazine is not conclusive, but is still very informative

Alain d'HYLAS · 29-10-2006, 13:49

Quote:

Originally Posted by craigsmith

So the SAIL magazine is not conclusive, but is still very informative

I couldn't agree more:

and from this test.. the best one seems to be the Hydrobubble!...

**Manson Anchors** · 15-02-2007, 11:38

I have to agree Alain, I am a wee bit dumbfounded on charts depicting which anchor is "best" based on one pull...or the combination of chosen pulls. Its not a science and the "conclusions" written on anchor test results are a far better guage. The intricate assesment of load-cell results can lead to huge discrepancies.

On the point of Warranties, look carefully at how long the Company has been around and how long you expect them to be around when it comes to honouring these warranties.
The smartest men in the room arent always around when you need them....

s/v 'Faith' · 15-02-2007, 12:08

I just got my 2007 West catalog, and the Manson Anchors are now a West offering.

No having to write away to Timbuktu and paying freight by elephant train like some other anchors.

I am not the worlds greatest fan of West, but if you buy it and don't like it you just take it back.

Maine Sail · 15-02-2007, 15:29

It is by far the finest anchor I have ever used even better than my steel spade!

hesap4tom · 29-07-2008, 07:57

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E-mail me and lets see what can i do for you. I can try to give some discount, free shipping, etc.
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