Anchors - Bigger is Better ?

[Kettlewell]

Not saying there aren't better anchors out there, but CQR anchors weren't "abysmal failures" in the days when they were competing with Bruce and Danforth anchors mainly. In most of the tests of the time CQRs had far superior holding to Bruce anchors, yet today we still see Bruce users, though some have gone for huge versions. In normal sizes I don't think they work so well. If I see someone anchoring up ahead of me with a Bruce I get the fenders out, and have often needed them. Maybe someone like Nick would be just as happy with a 176-lb CQR or Rocna or Manson or whatever. Not sure what he has tried in that weight.

One thing that I do think obscures things here is that we read a lot of stories of someone being unhappy with anchor X, so instead they get anchor Y and for good measure they double the weight, and now they jump in and say how Y is far superior to X. That isn't comparing apples to apples.

[55north]

Bigger is always better - at least with anchoring. Within reason though; I once considered putting one of these bad boys on the front of my Laser (useful between races when it gets windy) but was politely told that it would put it out of class.



If you're the type of person who worries about 30kg of extra weight on an anchor then you're at the top of a slippery slope - the endgame is snapping your crews toothbrushes in half and throwing the non-brushy bit overboard. If that's the case, you belong on Sailing Anarchy, not Cruisers Forum!

[JonJo]

Jim,

Unless you won a barge then beam is commonly a fixed proportion of length, it varies but not that much. Cats do not seem to have been seriously incorporated into the USL codes but most anchor makers make their own recommendations for multihulls.

The codes do not take into account a lot of things, underwater profile for example.

I'm not sure about displacement - as a 60' lightweight racing yacht is considered exactly the same way as a heavy displacement vessel. However the codes were drawn up when everything was a 'heavy displacement' vessel.

However the codes have been used for without debate for decades, many, and the anchor makers have developed their tables from the codes and I have naively (?) assumed they, the anchor makers, have taken 'H' into account. I also note that even with time and the introduction of yachts of light displacement that anchor makers tables have remained constant. These same codes are used by the CS and ISAF refer in their rules, in terms of anchors, to the CS (or class rules - which are similar).

The USL codes might be flawed - but they are universally accepted and as I say I have relied, maybe naively, on the anchor makers to interpret correctly.

[Kenomac]

Originally Posted by JonJo

Kenomac,

You obviously are smitten by the Ultra. Can I suggest you re-consider, quickly. Someone else has questioned your choice, but if you need stainless there is an option.

Spade make their bigger stainless anchors from a better stainless (I think from 2205 grade, you need to check, and also check when they start, ie size, to use the better grade). They will also sell the stainless models, maybe all of them, welded (if you do not like the jointed shank).

2205 has a yield strength of 450 MPa vs 205 MPa for 316. Doubling shank strength looks a no-brainer to me

The shank on the Ultra cannot be compared directly to the Spade since the ultra construction is a hollow core box section shaft which gives it comparable strength to the single plate steel shaft of the Spade. If I find myself in a situation where I'm in hurricane force winds or even 40 knots, I would, and have attached the Fortress 55 along with 40 feet of chain to the CQR or Ultra in tandem fashion in order to provide maximum holding power. I attach directly to the rode and not the primary anchor. No worries about the shaft bending; if it does, Ultra has a lifetime warranty.

But, thanks for the advice.

Ken

[foggysail]

Originally Posted by barnakiel

I can't help. And it is an example to show things CAN be computed, not an answer to what the actual values are.

If you want to say my computation algorithm is wrong, please point to the apparent mistake. There may be one. Till then considered correct.

20 kg anchor will have roughly 60% larger surface area than 10 kg anchor, so it will also have 60% higher holding power.

b.

Well start with mass where mass is = volume times density or if you rather, weight times acceleration. But just assume you meant weight instead of mass, just doubling weight has no relationship to holding. What was on my mind with that assumption left me considering two different Danforth style anchors one made of steel and the other made of aluminum where the aluminum anchor would have a much larger surface area to provide better holding even if each had the same mass. So mass didn't matter!

Now maybe if you meant to use a particular anchor as a base, then doubling its weight which results in a physically larger size should increase its holding ....not sure if JonJo will go along with that but I believe it will offer greater holding.

Anyway, that is where I got lost and gave up following your analysis.

[DumnMad]

JonJon. I repeat, the USL codes for shipping equipment apply for winds up to 60knots plus waves only. Ships are not supposed to hang around at anchor when winds exceeding 60kn are expected.
You can't transfer these rules to yachts that expect to be anchored through storms and hurricanes.

[foggysail]

Originally Posted by Kettlewell

Not saying there aren't better anchors out there, but CQR anchors weren't "abysmal failures" in the days when they were competing with Bruce and Danforth anchors mainly.

Geez Kettlewell, my old Bruce held the bottom as if it became mated to it PRIOR TO ELL GRASS. Now I can't make any comparison to the the CQR, I can however make a comparison to the Delta which is pretty close to the CQR. My Bruce never ever plowed. My Delta never ever stayed in one place. And a Danforth certainly has good great holding....sometimes.

Abysmal failures?? Before the Bruce, the CQR was the prized anchor to own. But like most things, time improves our options.

[JonJo]

Originally Posted by foggysail

Now maybe if you meant to use a particular anchor as a base, then doubling its weight which results in a physically larger size should increase its holding ....not sure if JonJo will go along with that but I believe it will offer greater holding.

I'm more than happy with that

I have not seen a 'real' Danforth and though they look the same (in an image) the fluke plate might have different thicknesses, the fluke edges and shank different profiles which will alter the ability of each anchor to dive.

Doubling weight, of the same design, does not double area because if you increase size (and hence holding) you need to increase strength (to withstand the load) which means thicker steel. So doubling weight would mean area would increase but not double! A way round this would be to use different steels, but then you would alter balance.

Reference was made, Kettlewell, to roll bars retarding diving - it should not matter that as the anchor gets bigger the roll bar also gets bigger - basically the resistance to diving caused by the roll bar should be similar for a big or small anchor. There is the issue of roll bars providing a restriction to flow of seabed through the fluke, causing choking. This should not be an issue in sand or mud, there is sufficient water (a seabed has about 18% water filled porosity, I think) for the mass to be simply extruded, but if there were any weed then the compressed mass might terminate diving completely. The Mantus has an exceptionally wide roll bar, basically well beyond the width of the fluke - and compression and choking might not be such an issue, with a Bruce and Spade with no roll bar there is simply no constriction.

In scaling up changes may not be exactly linear, hollow tube comes in standard sizes and in scaling up the tube (or thickness of the fluke) it might not exactly meet the ideal scaling. You can see this in the Rocna where the shank of the 20kg model is (or it was) the same thickness as the 25kg and 33kg model (because steel plate comes in standard sizes and they presumably decided the next size up of plate was too thick for the 33kg model (balance was wrong?). This is not unique to Rocna - all anchor makers have the same compromises, Delta have the same issues. In Rocna's case it does result in the 33kg model having a weaker shank than the 20kg model but this issue will be true of other anchors. The ideal is to have a thin shank, more streamlined, less resistance for diving, which is one reason for use of high tensile steels, you get strength and streamlining in one 'package'.

[JonJo]

Originally Posted by DumnMad

JonJon. I repeat, the USL codes for shipping equipment apply for winds up to 60knots plus waves only. Ships are not supposed to hang around at anchor when winds exceeding 60kn are expected.
You can't transfer these rules to yachts that expect to be anchored through storms and hurricanes.

I find it very unlikely that the owner of a yacht will intentionally allow his hull to be exposed to the full force of a 60 knot wind (even worse any waves) for any period of time. Hurricanes are well forecast and any sane owner will have scurried to the closest place of refuge (with shelter from surface wind), creek or whatever. He will have deployed a web of anchors and warps, he will have tied to trees, he will have the mainsail on the cabin sole etc. The mast top might be subject to 60 knots but I'm not sure how many yachts sit at anchor with 60 knots across the decks. I'm also not convinced that relying on one anchor 2 sizes too big is the answer either, the anchor might hold but I suspect some of the bow fittings will fail first - a web of anchors attached to multiple strong points seems more sensible but this demands having the spare anchors.

[noelex 77]

Originally Posted by Jim Cate

JonJo, you have not dealt with my major query about use of the USL codes: what height ("H") do you use to determine what the code says is the correct anchor? And why is there no involvement of the beam of the boat? Or of displacement?

How can you place credence in the application of this set of tables which are not at all formulated on sailing yachts and the anchor loads that they generate?

I'm still confused.

Jim

I don't put much faith in codes like this. At best they set out minimimum requirements.
If my reading is correct they specify 3m (10 feet) of chain of chain for sea going vessels (a whopping 6m if your anchor is over 25 KG.)
With specifications like this for rode I cannot think anyone would put much faith in the the table on anchor size.

onestepcsy37 summed it up

Originally Posted by onestepcsy37

"you can always tell how long a boats' been out there by the size and number of their anchors; the longer they've been out, the bigger the anchors and the longer the chain"

This is what happens. If you are starting out log distance cruising, do yourself a favour and go oversize on your anchor choice. It will save you money in " upgrades" down the track.

[DumnMad]

Originally Posted by JonJo

I find it very unlikely that the owner of a yacht will intentionally allow his hull to be exposed to the full force of a 60 knot wind (even worse any waves) for any period of time.

You obviously don't live in NZ.

[noelex 77]

Originally Posted by JonJo

I find it very unlikely that the owner of a yacht will intentionally allow his hull to be exposed to the full force of a 60 knot wind (even worse any waves) for any period of time. Hurricanes are well forecast and any sane owner will have scurried to the closest place of refuge (with shelter from surface wind), creek or whatever. He will have deployed a web of anchors and warps, he will have tied to trees, he will have the mainsail on the cabin sole etc. The mast top might be subject to 60 knots but I'm not sure how many yachts sit at anchor with 60 knots across the decks. I'm also not convinced that relying on one anchor 2 sizes too big is the answer either, the anchor might hold but I suspect some of the bow fittings will fail first - a web of anchors attached to multiple strong points seems more sensible but this demands having the spare anchors.

The concept that cruising boats can avoid high wind speeds at anchor, or at least always have enough lead time to prepare with multiple anchors, in mangroves etc is a nice one. I wish it was true.
Have a look at the video on post 54
Many of the boats were friends and no one was expecting anything like the severity they got.
The worst wind at anchor I have seen was when the forecast was only force 6. If you cruise long enough you will caught in one of these severe weather events sooner or later. Like severe storms at sea they are rare, but you need to be prepared.

I agree about the cleats, fittings etc, these need to beefed up on many boats. I have seen quite a few ripped out. ( whatever happened to Sampson posts) Two anchors don't help as the boat swings the full force tends to placed on one anchor (and therefore cleat) at a time.

[JonJo]

I confess that in the absence of anyone advising their 'correctly sized' new gen anchor dragged as a result of which they upgraded to 2 sizes bigger of the same style (going one size bigger would seem irrelevant) then I see no evidence to suggest that correctly sized new gen anchors are 'too small'. I appreciate you sleep soundly but no-one with a correctly sized new gen anchor has suggested they do not sleep soundly either. There has been some strongly stated views - but no-one has bought a new gen anchor and felt the need to upgrade (unless they bought a bigger yacht). Undoubtedly someone, somewhere will eventually post saying they have done just that, but statistically we need a decent population of upgraders and they simply are not there, or here (at least not yet). So you have strong views and arguments but not the key one for me.

I see world girdling yachts but few, count fingers on one hand, have new gen anchors. They carry anchors, very often not particularly big CQRs, I would not use as a garden ornament. But it could be they do not visit the tropics in the summer (so minimise Hurricanes, Cyclones and Typhoons), they might not visit Tasmania in the winter (so cutting out winter storms) etc.

[congo]

Hi all this is congo,I am hoping that my entry is not the result of another locked thread, as the last 4 threads that had our brand name exposed are all locked?

Anyway I will try not to upset anybody. I must congradulate JonJo for starting this thread, it has been extremely informative for all and I know from our experience in 20 years plus in anchor designs JonJo makes some very valid points.

NOELEX WROTE:
I don't put much faith in codes like this. At best they set out minimimum requirements.
If my reading is correct they specify 3m (10 feet) of chain of chain for sea going vessels (a whopping 6m if your anchor is over 25 KG.)
With specifications like this for rode I cannot think anyone would put much faith in the the table on anchor size.

As I stated above Noelex. I have been in anchor design and manufacturing for over twenty years, more testing of various anchor designs than you could imagine. You know DNV ,LIoyds,many more classifications and the like the N.M.S.C, A.M.S.A. all base their requirements when it comes to correct sizing of anchors, ropes and chains based on the USL code.

This system gets upgraded only when terms of documented evidence require based on fact. Yes the regulations are revisited on a regular basis for all to see.

The USL CODE, I was a participant when the National Marine Safety Commitee revised the shipping laws in leiu of the updated USL code, a new document was released---- 4/7/2007( National standards for commercial vessels) anchors chains and ropes are explaianed in part C design and construction, subsection 7D.

I sat as part of a team on the N.M.S.C. in Australia, what Iearnt there will always be invaluable to our anchor designing as part of the committee.

I will post this and see if the coast is clear, I believe I can make a contribution to this discussion if I can dodge the locks.

Regards Rex.

[noelex 77]

Originally Posted by JonJo

I confess that in the absence of anyone advising their 'correctly sized' new gen anchor dragged as a result of which they upgraded to 2 sizes bigger of the same style (going one size bigger would seem irrelevant) then I see no evidence to suggest that correctly sized new gen anchors are 'too small'. I appreciate you sleep soundly but no-one with a correctly sized new gen anchor has suggested they do not sleep soundly either. There has been some strongly stated views - but no-one has bought a new gen anchor and felt the need to upgrade (unless they bought a bigger yacht). Undoubtedly someone, somewhere will eventually post saying they have done just that, but statistically we need a decent population of upgraders and they simply are not there, or here (at least not yet). So you have strong views and arguments but not the key one for me.

I see world girdling yachts but few, count fingers on one hand, have new gen anchors. They carry anchors, very often not particularly big CQRs, I would not use as a garden ornament. But it could be they do not visit the tropics in the summer (so minimise Hurricanes, Cyclones and Typhoons), they might not visit Tasmania in the winter (so cutting out winter storms) etc.

I have been trying to think of any of my cruising friends that have the "recommended sized anchor" it's very rare most are at least one step oversized.

I do have friends with a 40 foot Lagoon (410 I think) they had a 20kg Spade ( which must be close to recommended size) and dragged several times. They have updated to a 25Kg Rocna this year ( I think they should of gone larger). They are not full time cruisers, but they sail 8-10 months of the year.
Its only a single data point unfortunately.

They anchored ahead of me ( don't you just hate cats sneaking in and getting the top spot )and they held perfectly in 35-40k for a couple of days the first time they used the 25kg anchor, as you would expect, but I kept a watch on them.
I would be nervous to be behind them in stronger wind especially with only a 20kg anchor.