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Old 29-03-2013, 00:42   #151
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Re: Anchor design and misnomers

SnowP

I hope you're right, and am sure your are ... but I'm not thinking about tiger country for this particular tactic -

note I said "any boat which sails in high latitudes", not

".... while sailing in high latitudes"....

as a frinstance, there's masses of NZ coastline still to explore! and although I'm not big on tropical sailing, I occasionally get my arm twisted, and I can think of times I wish I'd thought of this in coral country - where shorelines are off the menu

My feeling in general is that it never hurts to have some "off the wall" ideas 'up sleeve' for contingencies...

if I don't need them, so much the better.

But some of the classiest cruising moves I'm aware of were highly unconventional, and crafted in moments, cobbled together from snippets of other ideas - generally by people who were continually pondering different approaches to problems they had not yet needed to solve.
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Old 29-03-2013, 00:42   #152
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Re: Anchor design and misnomers

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Originally Posted by Andrew Troup View Post
Downunder

Sure thing, but not in this precise context.

I first struck the general idea a long time ago when a Nth Islander got washed over a river bar which wasn't as deep as the chart said (having touched coming up towards high tide - yikes!), he got pushed over sideways, long keel dragging, but of course it was too shallow to get back out when the boat was upright)

So he dug himself a trench, with a bunch of helpers. Of course, they did as much as they could at low tide, but coming up to high, he had a mate put on dive gear and clear it back out ('cause the trench filled up with loose stuff quite quickly, but it wasn't so hard to move). I think the guy was said to have wrapped a length of chain around each shin.

Andrew,

It is surprising what help and advantage a diver can be in many emergency situations.

But i doubt i would be voluntering for your proposition. Saving a distressed vessel is another proposition.

Cheers
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Old 29-03-2013, 00:59   #153
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Quote:
Originally Posted by Andrew Troup View Post
My feeling in general is that it never hurts to have some "off the wall" ideas 'up sleeve' for contingencies...

But some of the classiest cruising moves I'm aware of were highly unconventional, and crafted in moments, cobbled together from snippets of other ideas - generally by people who were continually pondering different approaches to problems they had not yet needed to solve.
Good point, I enjoy your ideas, and you never know, maybe oneday I will need to weild a shovel underwater to get my anchor to set. I just hope it will be somewhere warmer than antarctica... Keep the ideas rolling.
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Old 29-03-2013, 02:29   #154
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Re: Anchor design and misnomers

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Originally Posted by Andrew Troup View Post

I do anticipate a potential weakness (apart from, as you say, Big Pick bottoms) - and for me, the one which for me is currently "top of mind" and applies to all anchors, would be that old chestnut: a thin stratum of sand or mud (or crushed coral) over a hard layer - too hard even for a Big Pick.

It seems to me that the single big anchor fails here: as I think I posted elsewhere: much of the fluke area will be standing above the sea floor. Hard to get much grip on seawater...
In my current cruising ground this is my most common "bad substrate". Specifically a thin layer of sand over rock.

A big anchor does still hold much better than small anchor. The larger fluke area scoops and piles up a much bigger area of sand. Multiple small anchors would work as well, but only if you can even out the pull on rodes.

However, there is one drawback that has not been mentioned of BIB option. I find that even in a bad substrate like this my large anchor will nearly always hold full revs in reverse on the first drop.
This means the anchor will at least hold to 30-35k, but above this there is no guarantee.
With a big anchor if you don't dive their is no indication that the holding ground is poor (I have found cruising guides etc are very unreliable in indicating the areas with poor holding)

If the holding is variable with good and bad areas (and this is always the case to some degree) a big anchor will hold you in reverse even in the bad areas. With a smaller anchor multiple attempts will eventually find a relatively better patch, at least you then know the poor nature of the bottom.
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Old 29-03-2013, 07:01   #155
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Re: Anchor design and misnomers

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When I asked the question on the BIB thread no-one responded

The reason we did not respond to you is that most of us have ALREADY described our other anchors, when we use them and about how frequently. Jedi said 1%, which is about the right ballpark (for us more with the rocna and less with the Bruce/Ray). I have described using a delta as a tandem, loaning out our Ray when we were sitting on the Rocna, and rowing out danforths and fortresses, and having four anchors and four shore lines out during hurricane Lenny.

You just don't want to hear it because it does not fit your prejudice, just as you did not want to hear the "next gen" dragging stories.


which left me thinking maybe they just cross their fingers.

Yea, right, that's what the Dashew's, Jedi and I do, cross our fingers. We also like to sing Kum Ba Yah

BIB ......... Their anchors can be 40kg, instead of 25kg - a nightmare to manhandle,

Any decent seaman can lift and deploy very heavy weights with the equipment common on sail boats. Jedi has mentioned the technique he uses if he needs to dinghy out his anchor. We can lift and deploy a 50kg anchor out of our sail locker in about 2 minutes (from the moment we think of it) with a staysail halyard. At one time, in Chile when we were testing anchors to see which we liked, we had four 50kg anchors on board. We deployed them dozens of times a day. It's just something I prefer not to have to do at 2am in rain and a squall!

none actually seem to carry a second anchor.

Yea, right. Your reading comprehension is top notch.

I have been very polite so far, but I am going to tell you flat out that your theory that I would somehow be more secure (or even as secure) and sleep better if I used anchors which were half the weight of my current ones is simply ludicrous. Sure they would be less expensive, and sure they would bring less weight on board, but more secure??!! That's just plain and simple stupid.

...........
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Old 29-03-2013, 07:38   #156
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Re: Anchor design and misnomers

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.

have been very polite so far, but I am going to tell you flat out that your theory that I would somehow be more secure (or even as secure) and sleep better if I used anchors which were half the weight of my current ones is simply ludicrous. Sure they would be less expensive, and sure they would bring less weight on board, but more secure??!! That's just plain and simple stupid. ..........


That pretty much sums it up.
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Old 29-03-2013, 07:58   #157
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Anchor Cable

Danforth marketed a cable leader for their anchors for awhile, but I guess it didn't sell well enough to keep it on the market. I know that there are a fair number of people down in the Carolinas that have to anchor their boats out when hurricanes are coming, and for some the standard procedure is to use a wire leader to allow maximum diving of the big Danforth and Fortress anchors they typically use for multiple-anchor sets. I have corresponded with some about this and they are convinced the wire leader is the way to go in order to maximize the penetration.
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Old 29-03-2013, 14:44   #158
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Re: Anchor design and misnomers

Thanks Even,

Your summary is most succinct. And as you say you had commented prior, and your practice had been absorbed. Sadly you are one of few to have commented. If all the others had been as forthright I would not have asked, I was not asking you specifically to repeat what you had said already. Next time I ask a question I will ensure that if you have already answered in a previous post I will specifically mention that there is no need for you to further comment. You represent one person, or one yacht. And I am not sure you are typical, you might be but I do not know and it would be wrong to make assumptions.

Actually I do want to hear - that is why I asked the question, again and again.

Again thank you so much for your efforts. They are much appreciated.

Have a great sail, if the frequency of your ability to post reduces we will miss you.

Jonathan
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Old 29-03-2013, 15:14   #159
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Re: Anchor design and misnomers

Quote:
Originally Posted by estarzinger View Post
The reason we did not respond to you is that most of us have ALREADY described our other anchors, when we use them and about how frequently. Jedi said 1%, which is about the right ballpark (for us more with the rocna and less with the Bruce/Ray). I have described using a delta as a tandem, loaning out our Ray when we were sitting on the Rocna, and rowing out danforths and fortresses, and having four anchors and four shore lines out during hurricane Lenny.

You just don't want to hear it because it does not fit your prejudice, just as you did not want to hear the "next gen" dragging stories.

which left me thinking maybe they just cross their fingers.

Yea, right, that's what the Dashew's, Jedi and I do, cross our fingers. We also like to sing Kum Ba Yah

BIB ......... Their anchors can be 40kg, instead of 25kg - a nightmare to manhandle,

Any decent seaman can lift and deploy very heavy weights with the equipment common on sail boats. Jedi has mentioned the technique he uses if he needs to dinghy out his anchor. We can lift and deploy a 50kg anchor out of our sail locker in about 2 minutes (from the moment we think of it) with a staysail halyard. At one time, in Chile when we were testing anchors to see which we liked, we had four 50kg anchors on board. We deployed them dozens of times a day. It's just something I prefer not to have to do at 2am in rain and a squall!

none actually seem to carry a second anchor.

Yea, right. Your reading comprehension is top notch.

I have been very polite so far, but I am going to tell you flat out that your theory that I would somehow be more secure (or even as secure) and sleep better if I used anchors which were half the weight of my current ones is simply ludicrous. Sure they would be less expensive, and sure they would bring less weight on board, but more secure??!! That's just plain and simple stupid.
...........
JJ, you can add Ann and I to the list of folks who cross our fingers and hope for the best. We have found this technique to be very effective over the years. It appears that you use a similar technique in perusing the posts here on CF -- close your eyes and hope that no one notices that you have ignored contrary responses to your questions.

And Evans, thanks for the excellent summation!

Cheers,

Jim
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Old 29-03-2013, 15:44   #160
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Re: Anchor design and misnomers

What a touchy lot you are.

Sadly usage of second anchors is hidden, or lost in a myriad of posts and in many cases simply not stated. I am specifically interested in how those with bigger anchors handle them, as its not a technique that I need use. But I am sure its a technique that others might enjoy being shared - for the time we buy bigger yachts. Equally when I go to BIB it would be useful to know what that 'ocean of experience' uses. I do not know because I have neither the bigger boat nor the bigger anchor. Obviously if you do not want to reply and share your experiences (and everyone presumably has different ideas) then simply ignore the request. The fact it might be repetitive simply means I have not seen, nor remembered (if it has been previously posted), the answer, I never claimed to be perfect, nor became upset when people did not agree with me.
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Old 29-03-2013, 16:12   #161
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Re: Anchor design and misnomers

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What a touchy lot you are.

Sadly usage of second anchors is hidden, or lost in a myriad of posts and in many cases simply not stated. I am specifically interested in how those with bigger anchors handle them, as its not a technique that I need use. But I am sure its a technique that others might enjoy being shared - for the time we buy bigger yachts. Equally when I go to BIB it would be useful to know what that 'ocean of experience' uses. I do not know because I have neither the bigger boat nor the bigger anchor. Obviously if you do not want to reply and share your experiences (and everyone presumably has different ideas) then simply ignore the request. The fact it might be repetitive simply means I have not seen, nor remembered (if it has been previously posted), the answer, I never claimed to be perfect, nor became upset when people did not agree with me.
In our neck of the woods, williwaws are not uncommon up north, and tidal changes can create significant currents that exert a lot of force. My personal view of anchor design is that with most designs, weight is of primary importance, so I am definitely a BIB believer. My experience with a 44# Bruce on a 12 ton Cape George was ok, dragging only a few times over 18 years of cruising in the Pac NW and Hawaii. My experience with a 176# Claw is that once it hits the bottom, I'm not going anywhere. Maybe some other design would be better and I admit to a certain lust for an Excel since I am convinced it is the best anchor out there, but in the heavier weights, I have a hard time faulting the Bruce design. We drop it, let out about 3:1 1/2" chain, let it settle a bit, then add a 30' 1/2" snub line. This about 95% of the time. If we are in for a blow, say above 30 knots, I'll let out 5 or 6 to 1 chain, with the same snub line. I've only experienced sustained winds of 50 knots with gusts to 60 so maybe this tackle would pose a problem in higher winds but that's why we carry a big Guardian as well.

Delfin weather cocks nicely so we don't move around much at anchor and she doesn't present that much windage compared to other vessels so I feel pretty secure with what I have.

Needless to say, I'm not looking forward to raising the hook without hydraulics, but find the challenge to be able to do so by hand a bit silly. I can't fly by hand either, but have no qualms about using airplanes.
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Old 29-03-2013, 16:18   #162
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Re: Anchor design and misnomers

Go well Evans.

I hope your contrary winds are generally moderate, and your fair winds are frequently lusty!

And may your anchor unerringly find the G-spot at every opportunity.

Kia kaha, mate ! and... nihil illegitimi carborundum
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Old 29-03-2013, 16:33   #163
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Re: Anchor design and misnomers

Noelex:

I'm sure you're right to say a big anchor will tend to create a bigger 'burial mound' in that specific circumstance - particularly if it's a design with a pronounced 'spoiler' to prevent as much overburden as possible from spilling off the back end. (Clip-ons! ?)

Kettlewell:

The wire leader idea seems well worth keeping in mind as an up-sleeve add-on for specific challenges - thanks for that.
I'd kind of ruled it out for regular use, but it hadn't occurred to me to think of it that way.
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Old 29-03-2013, 16:39   #164
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Re: Anchor design and misnomers

Just ran the numbers on a formula I tweaked based on one that kettlewell came up with (credit to kettlewell for the basic idea, his bigness formula is Anchor wt(lbs)/LOA(ft)). This formula has been broached over on that thread, but it probably better belongs here...

The tweaks remove most of the scaling errors inherient in his simpler formula, This Formula is useful for comparing anchor Ulitimate holding capacity to windage for different sized vessels. The basic formula seems to apply right through roughly from cruise ships down to ten foot tinnies.

Quote:
LOA(ft)^2
Anchor weight(lbs)
The result may look something like this?
22-25 being BIB
25-28 being very conservative
28-31 being Conservative
31-34 recomended

This breakdown of the numbers can be argued about, very interested in your thoughts.

Behind this formula is actually quite a bit of thinking (for me at least) and it although it looks crude and simple it is not naive, and involved quite a bit of research and thinking, aided by this last few weeks intense anchor thread nerdery and all of your excellent inputs.

The use of weight rather than Anchor area is due to the way heavier anchors (of the same type) dive deeper, thus their holding increases by a power of about 0.92-0.94 or so rather than by 1 but at the same time windage on yachts increases by a power of 1.9 or so rather than 2, so these more or less cancel out.

LOA is the simplest number to use. We could possibly get better results using mast height, average length, or even by averaging Mast height, LOA and LWL. But KISS is better, and it is easier to apply this metric to anchor sizing charts this way.

Running a few numbers to test and get some benchmarks

Snowpetrel 33.5^2/45=24.9
Snowpetrel 33.5^2/35=32.1

Reiger 26^2/25=27.0
Reiger 26^2/30=22.5

QE2 1132^2/50700 =26.3 Proof it works?
Dinghy 10^2/5 =20.0 further proof?

Kettlewell-------38^2/45.....=32.1
Atoll--------------62.3^2/99..=39.2
ReMetau--------33^2/60.....=18.15!
Cfarrar----------42^2/55......=32
Panope---------34^2/44......=26.3
Paul L-----------44.......77.....=25.1
Painkiller--------41.....66.......=25.4
Oceangirl-------34......45.......=25.7
Jedi-------------- 64.....176.....=23.3
Target------------32.......60....=17.1 !
Boatsail----------27.......35.....=20.8
Don L-------------41.......55.....=30.6
Tim R-------------40........45.....=35.6
Sabray-----------44.......70......=27.6
Cpq--------------47........60......=36.8
Sailmonkey-----32........35.......=29.3
Mike OReily------37.......55.......=24.9
Oh drunk boy---22........16......=30.25
Delfin-------------55 ......176.....=17.18!
Minaret-----------52.......105....=25.7
FS mike-----------40........33.....=48.5
Onestep----------37........45.....=30.4
Lone wolf---------37........66.....=20.7
Pelagic------------65........98......=43.1
BobConnie--------51......100.....=26.0

CATS

Colemj............40......55....=29.1
Cotemar.........36.....500....=2.6
Jonjo..............38.......38.....=38

To run the formula the other way to find out a sensible anchor size select the bigness factor you want, say 25 for a decent BIB anchor

Then the formula is LOA^2/Bigness factor=anchor size So for snowpetrel it's

33.5^2/25=45lbs

For my new boat it's 40.5^2/25=65lb would be similar to Snowpetrels.

To allow for an aluminium anchor multipy or divide the Bigness factor by 2
ie 40.5^2/(25*2)= 33lb fortress or alloy spade

To allow for a next G SHHP anchor multiply or divide the Bigness factor by 1.25?

ie 40.5^2/(25*1.25)=52.5lbs (55lb)

Still need to sort out how multi's, light displacement and super heavy displacement boats fit, but at least it seems to me that we have a formula that roughly gives a more standard metric than manufacturers figures.
From here we need to fine tune the factors for different anchor types and boat types.

So final formula looks like

Quote:
(LOA^2/Anchor weight) x Factor1 x Factor2...= Anchor/length Ratio
Assuming the basic boat is an unmodified generic cruiser racer with a CQR we could possibly apply these factors? I ma not sure it's really worth the complication... but anyway I can't resist playing with numbers, so here goes.

Anchor Factors
  • 0.5? for alloy anchor
  • 0.8? for Next Gen anchor SHHP Anchor and danforth
  • 0.9? for HHP eg Delta
  • 1.0? for CQR, Bruce
  • 1.4? for fisherman anchor, dreadnought
Vessel factors
  • 0.8? for uldb (d/l less than 120?)
  • 0.9? for LBD (d/l 120-170?)
  • 1.5? for square rigger
  • 1.1? multihull
  • 1.1? for gaff rigs and bowsprits
  • 1.1?for heavy boat (d/l over 300)
  • 1.2? for very heavy boats (d/l over 400)
  • 1.1-1.3 for a boat that shears and sails at anchor badly
  • 1.1 for each roller furling headsail
  • 1.05 for a roller furling staysail

I have sort of just plucked these numbers out of thin air.. So by all means chime in with your thoughts.

By the way Nigel1, I noticed anchor handlers have exceptionally large anchors for there size, is this due to salvage and towing requirements. Their anchor factor falls in at around 8 to 16?

Maybe this should be in it's own thread, more relating to anchor sizing rather than design as such?

Cheers

Ben
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Old 29-03-2013, 16:46   #165
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Re: Anchor design and misnomers

Thanks Delfin,

The question over a second anchor is thus,

It actually does not need to be a big anchor, but if you follow BIB then your anchor might demand more than the direct muscle power of a cruising couple and thus becomes more of an issue.

Scenario

Your anchor becomes stuck, you needs abandon it (you might buoy it for later retrieval) but you now need a second anchor. Or you find your primary anchor does not work in the gravel bed, thin mud, hard substrate, in which you desire refuge (you know that because you have tried it 3 times). The final horror would be, in your case, the hydraulics fail. I understand you use, or carry, a Guardian - I assume that it is your fallback - and being a Guardian will be relatively easy to attach to your rode.

My thought was that if people were to say, carry a 55kg Rocna, they might also carry say a 55kg Spade, or Delta as a second and the Guardian/Fortress carried as a hurricane anchor. So I was really thinking of how to handle an equally large steel model (as opposed to an alloy as the only second anchor). I also wondered where they might store the second heavy anchor and whether they had 2 rodes.

People are carrying anchors, BIB, for worst case scenarios - your worst case scenario must be loss of hydraulics as your anchor is certainly large. As Evan said anyone with any modicum of seaman ship should be able to arrange use of a sheet or halyard winch but I suspect you have neither. So what is the fall back - as whatever you do might be applicable in other situations for other people

I had hoped to ascertain a good cross section of replies, but apparently they have already all replied with an equal clarity to your post and certainly cannot afford the time to repeat, even if they have the time to show frustration, whatever it was they said.

Chastened,

Jonathan
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