Oh goody, goody another anchor debate

Re: another anchor debate

Hylas, thanks for the reference.

I note that the angle tested was 145 degrees - typical of a tidal reversal.

I have to admit that my solution to tidal reversal is always to moor with two anchors, one uptide and one downtide. Mind you, those were the days when only CQR and fisherman anchors were available.

One element (obviously) not covered in the re-set story is the possibility of hooking weed or plastic bits which can so easily prevent any anchor (which flips) from re-setting, so I still use two anchors whenever possible . . . and if not, I stay aboard for the tide turn, or if there's a strong risk of a big wind shift.

While googling to find the article you quoted I came upon this very interesting link:

http://alain.fraysse.free.fr/sail/

It's quite the best published analysis of anchoring I've seen (obviously - since he agrees with all my views! But he does add a lot to my understanding) And sorry, I haven't read your Amazon reference, which may well be just as good.

His work isn't recent enough to cover modern anchors, he doesn't cover the lateral snatch effect on the anchor, and I'd question his conclusion that forces due to currents are trivial, since he doesn't allow for extra 'snatch' factor when a boat is yawing from side to side in a current.

But his caveats cover these issues, and his stuff seems to be a sound starting point for any debate on anchoring. He advises his less numerate readers to skip the equations and go straight to the conclusions of each section. Sound advice.
 
Re: another anchor debate

When the tide changes, and assuming you ride to the anchor and not the rode, what happens to an anchor - particularly a CQR?

Does a CQR invariably break out and dig back in again, or does it somewho burrow its way round?
 
I was surprised to read that the tests were carried out on three completely different sites, all of which seemed to have shallow water over sand. No rock or mud or kelp. So that'll be three identical sites. My much maligned (but not by me) Sowester plough on chain is in no danger of being replaced on these results.
 
Re: CQRs

[ QUOTE ]
The comments about CQRs only working in soft mud are correct

[/ QUOTE ](My emphasis). Given that you admit that you weren't actually using a CQR, aren't you overstating your case?

If that were the case, how come so many people, ourselves included, have been able to get consistently satisfactory results, up to and including gale conditions, from a CQR in sand and sand/shell/gravel mixes?

It seems to me that most people are getting good results from the anchors of their choice - otherwise they'd change them. I suspect that a lot of perceived problems arise from how they're set. Kelp is the greatest problem for us, and I readily admit that the CQR is not effective there.
 
Almost everyone thinks their own anchor is great. The reason for that is in the article. If all the anchors are capable of holding 1000 lbs, that covers 99% of anchoring for a normal cruiser. Very few will ever meet the sort of conditions that will separate a CQR at 1500 lbs from a Delta at 2500 or a Spade at 5000.

But I agree that three different sand-over-mud locations is hardly a comprehensive test. I'd like to see tests done on mud, hard sand, liquid mud and stone/rock.

I know from experience that in very soft mud a Delta is next to useless but a Fortress digs in like it's drilling for oil.
 
Re: CQRs

I take your point about my old anchor but when I swim to look at my anchor I have a nose round at other anchors and CQRs real or otherwise consistently lie on their side on sand. I carry five or so anchors, each different and I have carried out experiments on other types as well for the fun of it.

I watched more than 50 boats anchor under duress in a force five plus, over about two hours and the only boats that did not have to have two or more goes at getting a set were bugel and spade types. It proves nothiing because I suspect those without anchoring success were on charter boats with all that that implies.

In short all anchor types can set and hold and all can fail to set or not hold, depending on the bottom, technique and conditions. We may develop the perfect leisure boat anchor one day but we haven't done it yet.
 
Re: another anchor debate

There's an 'Anchor size' thread going on in the PBO forum in which I've explained my use of two anchors in various situations.

In the up tide, down tide situation, you ride to alternate achors, both of which are dug in to the appropriate direction, so there's no flipping.
 
Re: another anchor debate

Loved this article, well written and helpful.
However can't help noticing that:
As noted in previous posts, all three sites were somewhat similar with sand.
Curious, as article notes, that anchors were persuaded to penetrate with a less powerful craft than Shana Rae, even though Shana Rae increased revs (in astern) gradually. I'm baffled! can anyone suggest an explanation?
Also odd that, of the two Danforth-shaped anchors, one performed brilliantly ond one very badly. Again, I'm baffled.
And finally - that anchor rode was 20 ft on 5/16" chain plus nylon rope. Chain presumably weighted about 10 kg, or 22 lb if you prefer. Does anyone use so little chain? (even my little boat has 15 m of 8 mm) ... seems to me that the whole rode would start lifting off the bottom with a pull of about 100 lb, ie anchor gets a yank upwards just as it's thinking about digging in. I'm surprised any set at all, even more that some did on a 3:1 scope. It's a very severe test (this might have been a good thing in context, and would have differentiated betwen the most-reliably-setting and the rest) and it's arguable that more anchors would have set had more chain been used.

Pretty impressed with a 5000 lb tension, it's about as much as my little boat weighs ....

I do so love anchor threads!
 
Re: another anchor debate

[ QUOTE ]
Curious, as article notes, that anchors were persuaded to penetrate with a less powerful craft than Shana Rae, even though Shana Rae increased revs (in astern) gradually. I'm baffled! can anyone suggest an explanation?

[/ QUOTE ]We understand that the location tested the 2nd time was different again (softer sand).

[ QUOTE ]
Also odd that, of the two Danforth-shaped anchors, one performed brilliantly ond one very badly. Again, I'm baffled.

[/ QUOTE ]In actual fact, if the Fortress result of "max before releasing" is corrected to be comparable to that of the West Marine Performance, i.e. by considering a ratio of holding power to anchor size, the average performance appears fairly similar. You can see this on our own graph of results based on SAIL's version of this article, on our website.

The Yachting Monthly article does not draw a distinction between the "max before releasing" (holding power) and absolute peak pull (while dragging).

It is a pity that greater effort by both magazines was not put into the analysis of the data. Much confusion has resulted.

The negative comments from both magazines however should illustrate the general problems with copies and clones of genuine anchors. Indeed West Marine themselves should be fairly embarrassed about the anchor they consider "to be as close to our ideal anchor as possible." This in the product blurb for the Performance - they go on to say "We believe we actually improved on several aspects of the original designs of Bob Ogg and Richard Danforth."

/forums/images/graemlins/crazy.gif

[ QUOTE ]
And finally - that anchor rode was 20 ft on 5/16" chain plus nylon rope. Chain presumably weighted about 10 kg, or 22 lb if you prefer. Does anyone use so little chain?

[/ QUOTE ]Americans /forums/images/graemlins/grin.gif

With respect to your comment about the chain lifting off, in fact it doesn't make much difference. Unless you're using all rope, any anchor will begin to set with an effectively horizontal pull on it, as it is initially incapable of providing enough resistance to allow the rode to be pulled close to straight. It doesn't make much difference how much chain is used.

And of course by the time you're applying several tonnes of force to the rode, it will be practically straight, whether all chain or not.
 
Re: another anchor debate

Not an explanation but a confirmation - my Delta slides merrily across the sea bed unless I set it very slowly. Any attempt to set it using reverse and I'm dragging backwards rapidly. I've seen the same with a Fortress.

As for differences between similar anchors, it's a common experience. It may be down to fluke angle, sharpness of tip or half a dozen other differences. Also, the performances may well be reversed in different conditions.

I think any rode would be pretty much a straight line with 5000lb pull on it, chain or no chain.
 
[ QUOTE ]
Yes. The FX37 weighs 10Kg. If the same anchor (same size) was in steel, it would weigh 28Kg, and as you can see the other steel anchors tested weighed around 15Kg - not exactly a fair comparison.

This is one of the reasons we made our own graph of the testing, so as to measure holding power results against each anchor's size. There is even some considerable variation in size between the steel types.

[/ QUOTE ]

Much of the argument seems to hinge around this point. You need weight (to dig in) and you need surface area (to hold). So the perfect anchor is heavier than you can manage, and bigger than you have space for. But if you can manage a 35 pounder, and you have space for a 35 pound aluminium anchor, why should you settle for a smaller 35 pound steel anchor?

An objection to this argument is that aluminium is not as dense as steel, and weight in water is reduced by anchor's displacement. A steel anchor loses about a fifth of its weight, and no doubt there is a Scuttlebutter out there who knows how much more an aluminium one loses. But none of the contributions so far have alluded to any setting problem that is peculiar to the aluminium version.

Mark (two 33 lb Bruces, one 22 lb Delta, one fisherman's and looking to acquire a bigger flatter anchor) Walker
 
[ QUOTE ]
Much of the argument seems to hinge around this point. You need weight (to dig in) and you need surface area (to hold). So the perfect anchor is heavier than you can manage, and bigger than you have space for. But if you can manage a 35 pounder, and you have space for a 35 pound aluminium anchor, why should you settle for a smaller 35 pound steel anchor?

[/ QUOTE ]In addition to weight under water, there are many disadvantages of aluminium that don't get tested. Particularly strength and durability. We don't make an alloy version of the Rocna, because we don't feel we can get adequate strength from it. Also cost.

Your logic is valid, but in that scenario, if you need a 35lb aluminium anchor because that's the appropriate size, then for general purpose anchoring you should really be prepared to accept say a 70lb steel anchor. Alloy anchors have a place as spares and on boats that must save weight (racers), but for 'normal' anchoring should be avoided.
 
To be a fair comparison,

[ QUOTE ]
<span style="color:blue"> Yes. The FX37 weighs 10Kg. If the same anchor (same size) was in steel, it would weigh 28Kg, and as you can see the other steel anchors tested weighed around 15Kg - not exactly a fair comparison. </span>

[/ QUOTE ]

It could be perfectly OK to correct results in relation with some parameters;
- But also to be fair, this has to be clearly explained
- And the same correction should be applied to ALL anchors ..

For example, the 15 kg Spade has a blade surface area of 800 sq cm² and the 15 kg Rocna has a blade surface of 1030cm² or about 28.75% more than the Spade and most others tested anchors.

To be a fair comparison, then the holding results of the Rocna should be divised by 28.75 %
 
[ QUOTE ]
In addition to weight under water, there are many disadvantages of aluminium that don't get tested. Particularly strength and durability. We don't make an alloy version of the Rocna, because we don't feel we can get adequate strength from it. Also cost.

[/ QUOTE ]Witness the fact that even the massive Fortress failed in the testing - during their veer pull, YM reports the shank bent slightly, SAIL reports the fluke bent slightly. YM has demonstrated a little more attention to detail, but then the fluke is the more likely to fail. Perhaps it was both.

SAIL say:

"This was while the anchor was under load, so it would be unfair to say anything other than it withstood a tremendous amount of abuse and still functioned properly"

We disagree, the above statement is tantamount to saying that it is acceptable for a product to fail when it is put to use in extremes which it is supposed to be able to handle.

Neither magazine makes a big deal out of this, but an anchor managing to damage itself just in sand is something we would consider unacceptable, and is an excellent illustration of the above arguments concerning aluminium.
 
In the weekend i was talking to a gent who has arrived home from 9 years at sea in a heavyish 37fer.

Talking about anchoring and the alloy anchor he had on the front I asked "why alloy and not steel?" (being nosey I do this a lot), answer was weight on the bow (which I did think was a bit strange considering all the stuff already loaded up there, but never mind). I asked if he was concerned about the alloy bending under load, his answer was "take a look at this".

'This' was a bit of Italian made 8mm short link which had stretched (I know this takes over 2000kg) and the very solidly built bow roller/fitting made from 50 x 12mm stainless steel, which was well bent. This was from 2 days of "well over 50 knots and some nasty waves". Not strangely this gent (who writes for many mags around the world) thinks his anchor is the greatest thing since mum caught her tits in the wringer. That alloy (primary) and a genuine Bruce (smaller secondary) replaced to good CQR copies which were chucked off a few years ago due to "being a pain in the ar*e".

Tha alloy anchor was fine, no paint left but not bent in anyway. He was a bit surprised (he was expecting to find some damage on retrieval) as I was but goes to show alloys must be a lot stronger than I and a few others have thought.

It was not a Fortress. Strangly I have seen a lot more bent Fortress's than straight but the owners are still happy they work.

Go Alloy anchors you strange but wierdly wonderful things (maybe) /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
 
Re: To be a fair comparison,

NONONO, the point is not about awarding arbitrary handicaps to make a particular brand come out top. When I raised the point it was about the fact that the test was supposed to be of anchors recommended by the manufacturers for boats of 35-40 ft. The Fortress tested was 1-2 sizes above the manufacturer's recommendation.
 
[ QUOTE ]
Alloy anchors have a place as spares and on boats that must save weight (racers), but for 'normal' anchoring should be avoided.

[/ QUOTE ]

My interest in aluminium is almost exactly for those reasons. I'm no racer, have a 38 footer displacing 7.5 tons unloaded, and use a 33 lb Bruce for general purpose anchoring. Backing that up are another 33 lb Bruce, a 22 lb Delta and a fisherman's. Between them, those seem to cover most eventualities in moderate weather, but I'm not confident that they would hold the boat in a real blow.

Why not get a heavier main anchor? I'm not sure the anchor locker could take a bigger one, and I know I would struggle to lift a heavier one out of it. 450 or so quid may seem a lot to pay for a piece of aluminium kit that will be used rarely, if ever, but, to use the phrase so beloved of Scuttlebutters, what price peace of mind?
 
Re: Kelp

Our Spade seems to work remarkably well in kelp . . . it's sort of sharp and curvy, so maybe it cuts its way down through it. We have anchored a couple of times in Craighouse and a couple of times in Canna - both very kelpy - with no problem - able to set it (sometimes second go though) and use max reverse.

It does however tend to come up with a huge ball of kelp on it, which caused no end of hilarity on one of those occasions in Craighouse. (Anecdote HERE)

All Spade owners I have ever spoken to have been very happy with their choice of anchor . . . but then no-one is likely to say 'oh no I'm a wally, wasted my money, drag most nights' are they?

I love anchoring debates . . . FWIW we have never dragged with the Spade, and that is good enough for me. On the other hand, we do use a lot of scope and set it properly . . . any badly anchored fool can drag whatever the shape or size of the anchor.

- Nick
 
Re: Kelp

I'd agree with your comments about the Spade. Mrs_E, she who lowers and raises the anchor, reckons the only problem is that it inevitably comes up with half of the surrounding seabed attached again much to the amusement of any audience.
 
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