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Old 10-21-2011, 06:50 AM   #1
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Do anchors scale?

I have a curiosity question (idea from another thread): Do anchors scale up and down? Meaning, because a large boat has Anchor Type X, does that mean it's right for smaller boats in the same area? If I walk arournd a marina and see a 100' yacht with a Danforth or Bruce or plow anchor (just to name a few), does that imply that they know something you don't? What about commercial boats? I often see people arguing about anchors, eventually pull out a picture of a Navy ship or commercial fishing boat and state - "If it works for them, it will work for the rest of us."

Just curious.

Tom-


-- Edited by GonzoF1 on Friday 21st of October 2011 06:50:52 AM
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Old 10-21-2011, 07:30 AM   #2
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RE: Do anchors scale?

Tom, on a pleasure boat you pick an anchor on how it looks.* The shinier the better.* Walk the docks and see the pretty anchors on the bow pulpits.* I think the best ones are teflon coated because it doesn't seem that mud sticks to them.
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Old 10-21-2011, 10:27 AM   #3
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RE: Do anchors scale?

If the anchor is showing a little rust, maybe there's a stain running down the hull. A few chips in the gelcoat at the bow just below the pulpit, old shackle with the shackle pin siezed, etc. Then I might talk with the owner about his anchoring experiences with that anchor.

Nice shiny obviously rarely used anchor I'll ask how much extra it costs for electricity at the various marinas.

*
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Old 10-21-2011, 11:24 AM   #4
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RE: Do anchors scale?

Gonzo,

I think they do * ......to a point. There is the Reynolds number and to a freighter your sand may be viewed more like rocks to the freighter. Also imagine what it must be like to break out if a fully burring anchor like a Delta on a freighter. Sized up to a Delta weighing tons I suspect. So I'd say not fully in extreme examples. But if you saw an awesome anchor on a 75' yacht I'd say it would work at least 99% as well for you as it does for him. A Claw on my 16' aluminum skiff will work as well on your trawler as on my skiff. Provided our anchorages (especially the bottoms) are fairly similar. Something else enters into what I think you're seeing Gonzo as people do tend to keep the anchor on a used boat that they buy. A fisherman (actually a woman) had a big Danforth on her bow and I asked her why she had a Danforth how did it work for her. She did'nt have a lengthly response. She said "came with the boat". So if you have a 30 yr old boat you probably have a 30 yr old anchor aboard. I did until*I started mess'in w the situation. I've used the old anchor many times and it's always worked flawlessly but newer anchors work better * .....how much better?? I'm not really sure but I AM sure they don't work nearly as well as the much talked about anchor tests say or indicate they do. The tests indicate old anchor designs are almost totally worthless and they obviously aren't. But getting back to your question * ...the way you asked it I'd say yes. Relative to our boats on this forum I'd say yes they scale well. That is my opinion.
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Old 10-21-2011, 12:03 PM   #5
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Do anchors scale?

Quote:
GonzoF1 wrote:
I have a curiosity question (idea from another thread): Do anchors scale up and down?
I believe the answer to that depends on the anchor's design.* I think they'll all scale up, if by that you mean they retain their performance as they get bigger or heavier.* I don't believe they all scale down, however.

While weight is not the deciding factor of an anchors effectiveness, a heavier anchor can make up somewhat for that anchor's deficiency in design.* The Bruce is a great example of this. Originally designed to weigh many, many tons in huge sizes for securing floating oil exploration platforms in the North Sea, at those sizes it is very effective.

So somebody at Bruce got the idea that if it works so well in its original gigantic sizes, if it was scaled down, it would work just as well on little bitty boats like the kinds we have.* Well, it doesn't as we and a number of people we have met over the years have found out the hard way.

Part of the problem, in my opinion, is you can scale the anchor down but you can't scale the bottom down.* Sand is sand, and sand penetrated by a huge, multi-ton Bruce anchor is the same sand that is penetrated by 33 or 44 pound Bruce anchor.* And I don't think in its small sizes, the Bruce design can hold very well in that same sand (or mud or whatever).* It sets quickly, which is why it's so popular, but its holding power is rubbish.* This is not me talking, this is confirmed in virtually every anchoring test I've ever seen in which a Bruce is one of the anchors tested.

The recommended size of a Bruce for a 36' boat that weighs in the neighborhood of 28.000 pounds (GB, CHB, IG, etc) is 33 pounds.* It's not uncommon for people with 36' boats to put a 44 pound Bruce on it.* In the instances I know of the people we know with boats in this size range and either weight of anchor have had similar problems with holding--- am eleven pound increase in weight plus the slightly larger size made little or no difference in holding power.

But if you were to put a 66 or 88 pound Bruce on that same 36' boat (I don't know if a Bruce was available in 88 pounds but let's assume it was) the holding would be a lot better.* Why?* Because that's a lot more brute weight plus a larger fluke area to resist dragging to help hold that same 36' boat in place.

I think going to a larger size with just about any anchor design will improve holding and maybe even setting if you have to punch through a crusty or weedy bottom.* More weight will help with holding and, depending on the anchor design, penetration.

But how much weight is practical for your boat?* If we'd have put an 88 or 100-plus pound Bruce on our 36' GB, we probably wouldn't have had the dragging problems we had.* But carrying, deploying, and retrieving that size and weight of anchor would not have been practical on our boat.* So that's the big trick--- to design an anchor that hits that magic formula of abilty to set fast, have very good holding, and is small and light enough to carry and use on your size of boat.

There are designs out there that come pretty close to achieving this formula and designs that miss it by quite a bit.* Which ones hit it and which ones miss tends to be a personal opinion based on one's own experience.

As someone said in another thread, the best anchor in the world is the one that hasn't dragged on you yet.


-- Edited by Marin on Friday 21st of October 2011 12:07:22 PM
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Old 10-21-2011, 12:55 PM   #6
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Do anchors scale?

Quote:
Marin wrote:
As someone said in another thread, the best anchor in the world is the one that hasn't dragged on you yet.

*
*That's about the only thing I've said on this forum where someone has not yet disagreed.

I'm one of those guys who has a 33# Bruce copy on the bow of*a 36-foot boat.* Not worried about it yet because I'll be anchoring in protected waters with firm mud bottoms for the immediate future.*

The most common anchor arrangement in my part of the marina, containing mostly 37-50-foot boats, is both a CQR Plow and a Bruce on the bow.


-- Edited by markpierce on Friday 21st of October 2011 12:56:26 PM
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Old 10-21-2011, 01:05 PM   #7
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Do anchors scale?

I have no idea if this is true--- or is still true--- as I haven't lived in the SFO Bay area since I* was a wee lad and back then I wasn't paying any attention to anchors (although I was paying attention to boats). But we were told when we bought our GB, which until we got it had spent its whole life in SFO Bay, that the most popular anchor in the Bay is the Danforth. This is what was on our boat when we bough it, fore and aft, and it made sense as it's my understanding that most of the bottoms people anchor in down there are mud. And a Danforth or an anchor of the same basic design, like Fortress, consistently tops the anchor test lists in holding power in mud (and sand). If we lived there and had the boat we have, I suspect we'd have stayed with the Danforth based on what I've read and seen in tests.


-- Edited by Marin on Friday 21st of October 2011 01:06:14 PM
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Old 10-21-2011, 01:10 PM   #8
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Do anchors scale?

My impression is that the Danforth-type is still the most common anchor in the Bay Area.* But the larger the boat, the less likely it is the primary anchor on display.* I have a Danforth-like Fortress anchor as backup to my claw.

A large recreational trawler (not mine)*at my marina:


-- Edited by markpierce on Friday 21st of October 2011 01:21:49 PM
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Old 10-21-2011, 02:00 PM   #9
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RE: Do anchors scale?

I'll tell you a real disadvantage of a Danforth-type anchor, and it's got nothing to do with setting or holding. If your boat has a short pulpit and a plumb or nearly plumb bow-- like a GB-- if the anchor comes up out of the water and starts to rotate or swing (or both) for some reason like boat movement, wind, whatever, that long stock will come around and whack the stem of your boat, usually several times as it comes up to the pulpit. Our boat has a whole series of chips and dings in the gelcoat on the stem from the previous Danforth-type anchor that was on it prior to our purchasing it. One of these days I'm going to use these as a way of practicing filling and fairing gelcoat dings and chips, which we'll have to a lot of prior to painting the boat (someday).
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Old 10-21-2011, 02:01 PM   #10
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Do anchors scale?

I am so confused after reading about anchor for the last 10+ years, I dont think there is any ONE anchor that fits all boats and or bottoms.* So I have three anchors in the 70 lb range, a Danforth for sandy/light sea growth bottom, a QCR for hard/heavy sea growth bottoms and a Forjord which is what most large commercial/pleasure boats have which is sort of in between a Danforth and QCR.*
*
When we bought the boat it had come up from California and it had the QCR on the bow, with the Danforth laying on the deck.* The first time we tried to anchor was with the QCR at Poulsbo which is a sandy bottom, dragged and plowed up the bottom.* We switch to the Danforth which set and held. **So the Danforth was the primary anchor for several years until we moored on the larger pleasure and Commercial boats, and noted they mostly had Forjord which look like a navy style anchor.* Now the Forjord is the primary anchor, but still have the QCR and Danforth as back up.
*

The most popular anchor on pleasure boats under 45 ft is the Bruce over 45 ft its the Forjord.* I have noticed a few Rocna, the new anchor on the market, which I think would be a good replacement for the QCR, but there are + and - for both.* I am still betting on the Forjord for the PNW.* Like they said, That is what the commercial use, so if it good for them, it should be good enough for me.* Besides we are more commercial looking than pleasure anyway.***


-- Edited by Phil Fill on Friday 21st of October 2011 02:27:35 PM
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Old 10-21-2011, 02:06 PM   #11
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Do anchors scale?

Marin,

You say the Bruce's performance is "rubbish" and I say a lot of what you say about the Bruce is rubbish even though I agree that the Bruce is not a high performance anchor. And I'm not trying to offend you. You've always said the Bruce tends to "break out" and I disagree in that I think the Bruce frequently is'nt "in" in the first place. I think they set frequently on 2 of their 3 flukes laying on their side w one fluke above the bottom. I think the Bruce will bury deeply and hold well w enough scope when all three flukes have engaged the bottom. But a full house and 2 pair are very different. That's why a Bruce needs to be so big. Only part of it often works or is engaged. That's why it will frequently drag when it blows. And it is you talking on your post. Just because somebody says something in an anchor test dos'nt mean it's true at all. There is much in many anchor tests that can't possibly be true. But I've learned much from the tests. In one test a Claw came out top dog. In one test my original XYZ came out top dog too but it dos'nt mean the're top dogs. I'm talk'in about dogs cause I know you like dogs. But any anchor that sets consistently is not at all bad and I'd rather believe a Bruce is good judging by how many fishermen have them than how they performed in an anchor test considering that most anchor tests have considerable manufacturing interests involved. I may have said this before but I suspect that if you gave up half your chain (the boat end preferably) and put that weight into a claw anchor you may very well have that 88lb anchor and never drag again. And I don't see that carrying, deploying and retrieving that anchor would be a problem. You have a very good winch to do the work for you. Someone said "the best anchor is one that hasn't failed you yet" * ...said nothing about dragging and dragging is'nt necessarily failing until one drags onto the beach.*


-- Edited by nomadwilly on Friday 21st of October 2011 02:08:34 PM
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Old 10-21-2011, 02:21 PM   #12
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RE: Do anchors scale?

Quote:
nomadwilly wrote:

*dragging is'nt necessarily failing until one drags onto the beach.*
*Wow!!**Eric very profound. Well said.

SD*
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Old 10-21-2011, 02:29 PM   #13
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Do anchors scale?

Eric--- You're correct in that my opinion about the Bruce is just my opinion based on our experience. The fact we have met so many other boaters who have equally poor success with the Bruce (in various sizes, some larger than the one we used) just means these other people all had bad luck with them, too.* But this doesn't negate the good experiences other people have with them.

And you may well be correct in that the Bruce tends to set on just two flukes, or one and a half flukes. What you say certainly makes sense to me based on what the design looks like and the anchor's blunt, dull-edged flukes. Perhaps this is why it works well in big giant sizes but not so well in the smaller sizes like our boats use.

If I had looked at just a few anchor tests I would certainly agree with you that they don't tell all. But I've looked at tons of them, not only after buying our Bruce in 1998 and reading about anchors on and off after that, but particularly during our search for a different anchor type after our Bruce let us down one too many times.

And in every test I read, in every bottom type, the Bruce was always at or near the bottom of the list in terms of holding power. What struck me over time was that the top performers always varied quite a bit from test to test. But the Bruce was always at or near the bottom in holding power.* That has led me to conclude that the anchor is rubbish in terms of holding power compared to most of the other anchor types that are typically tested, which includes Danforth-types, CQR, and the so-called "new generation" anchors like the Super Max and so on (I know you don't like that term but that's what the magazines and testers call them).

We are very happy with the anchor we have now and have no reason at this point to consider trying something else.* I'm sure there are ways to "fool" a claw-type anchor like the Bruce into holding better, but I don't see any reason for us to try.* In our case, it's a matter of "if it ain't broke, don't fix it."* Our Bruce was "broke" so we fixed it.* If the anchor we have now ever lets us down the way the Bruce did, well then we'll "fix" that, too.* But until then, we're happy campers.

And besides we need the Bruce at home to prop open the door it's holding :-)

As to so many fishermen apparently having them (I've never seen a Bruce on the seiners and gillnetters in our marina but maybe it's popular up where you are), I recall you saying the commercial guys use all chain and dump most of it on the bottom when they anchor to the point where the anchor type is almost irrelevant.* Under those conditions, a Bruce would probably perform pretty good with a half-ton of chain piled on top of it :-)


-- Edited by Marin on Friday 21st of October 2011 02:33:06 PM
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Old 10-21-2011, 02:51 PM   #14
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RE: Do anchors scale?

I duly note that the Bruce*is rubbish. Please don't tell my Big Bruce that as I prepare to subject him to*another anchor test next week without letting me down yet. During the past few years I had taken note of anchor expert's sage advice and*was dutifully prepared to throw Big Bruce away as Rocna, Sarca, Manson etc got hyped. But Big Bruce just kept unfailingly doing his stuff in all sorts of bottoms and wind, full gales in fact.

I read somewhre that Bruces were designed to hold oil rigs in place in the North Sea. Until I lose Big Bruce, I'll just continue to rely upon this ancient North Sea design.
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Old 10-21-2011, 05:25 PM   #15
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RE: Do anchors scale?

Quote:
sunchaser wrote:
I read somewhre that Bruces were designed to hold oil rigs in place in the North Sea. Until I lose Big Bruce, I'll just continue to rely upon this ancient North Sea design.
They were, and that's the issue.* For the North Sea oil rigs, the Bruce anchors are monstrous and weigh many tons.* At that weight and size and scale to the bottom, they work great.* But--- in my opinion---*the design and the associated performance doesn't scale down to the size of anchors most of us use on our boats.* Particularly when you get into the sizes recommended for boats in the 25-40 foot range or so.* As Eric noted, their design and*blunt, dull fluke edges*most likely prevents them from digging all three flukes into the bottom, so you're not getting the full benefit of the total fluke area.

But a lot of people have really good luck with Bruce anchors so there's no reason for them to change unless their luck changes.* We changed because we had too many instances of poor holding--- good initial setting but very poor holding under higher wind conditions--- so we went in search of something better.* Had we not had the holding problems we did, we'd still have the Bruce on the bow.* The same is true of a number of other people we've met over the years.

As with anything, every anchor design will be failure-free for you*until the first time it fails :-)
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Old 10-21-2011, 05:39 PM   #16
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Do anchors scale?

Quote:
nomadwilly wrote:
I think the Bruce frequently is'nt "in" in the first place. I think they set frequently on 2 of their 3 flukes laying on their side w one fluke above the bottom.
*Hey Eric, here's a theoretical thing to think about.* You have often said how excess weight in either end of a boat is a bad thing (I agree) and that carting around an all chain rode doesn't contribute to anchoring success and so*is just excess weight (with which I don't agree).

But how about this....* A person has a Bruce anchor (or any similar claw anchor).* I think what you say is plausible and that one or maybe even*one and a half of its flukes don't dig in when the anchor sets.* So that person's boat is being held only*by the portion of the flukes that does dig in.* So this person is, in essence, carting around the weight of at least one fluke, if not one and a half or so, for no reason since it rarely supplies them with any holding power.* But since there's no way of knowing which side an anchor will dig in on, the person doesn't know which of the Bruce's flukes to saw off and thus eliminate the excess weight.* So he has to cart around all three of them.*

So a Bruce, besides having poor holding power, also forces one to cart around a bunch of weight in the bow that does one no good whatsoever.

What do you think :-)


-- Edited by Marin on Friday 21st of October 2011 05:41:01 PM
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Old 10-22-2011, 12:33 AM   #17
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Do anchors scale?

*Marin,

"and that carting around an all chain rode doesn't contribute to anchoring success"



If you had said "carting around the upper half dos'nt contribute MUCH to anchoring success" you would have been correct. The upper half or especially the upper quarter contributes so little to anchoring success that all that weight should be put to better use elsewhere *...like in the anchor. Your 3/8ths chain weighs 1.7 lbs per foot. You prolly have 300' of the stuff so half that chain weighs 255lbs. Your present anchor is 45 lbs so if you switched to half chain you'd be able to have an anchor weighing 300 lbs. And w that 300 lb anchor your rode will be exactly the same weight as what you've got! If you traded more chain for anchor weight you could have a 500 lb anchor with the whole rode weighing LESS than your present anchoring system. I think it's safe to say you'd be better off w even a Kedge anchor of 500lbs. And I also think it's safe to say (considering these numbers) that a combination rode is best and an all chain rode carries a great weight penalty.*

As to your "theoretical thing" all anchors have parts that don't contribute 100% to holding power. Weighted fluke tips. Stocks. The other fluke on a Northill. The big hinge on a CQR. Roll bars. The XYZ is the least affected w parts and weight that aren't directly related to holding the boat in place and keeping the anchor from breaking out. Only about 5% of the fluke basically dos'nt "work" and the shank is obviously the smallest and lightest there is. In you're example you're assuming all three flukes are not burried and I'm positive that was'nt the way it was intended to work. Before you/we can consider your example we need to know if my guess about the unburried fluke has any merit all. But if my new 16lb claw can't be dragged w my boat can we assume all flukes are buried? Tom prolly backs down smartly on his Bruce and if he could make it drag in reverse gear he'd prolly be criticizing it instead of praising it. Prolly lots of others that could weigh in on this but would rather not get involved. On our trip to Alaska in 03 on my Albin I had a Bruce and did experience occasional dragging while setting it. Always got it to set though. No howling wind so can't make any claim to max holding power. Anyway I'm going to buy the claw now and compare it w my other anchors as best I can.

As to whether Bruce's are popular up here I stated that is so. So there's no "maybe" about it. AND they are popular here on this forum too.




-- Edited by GonzoF1 on Saturday 22nd of October 2011 10:09:37 AM
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Old 10-22-2011, 07:52 AM   #18
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RE: Do anchors scale?

Every commercial ship I have sailed on uses as much chain on as long a scope as possible. The weight of the chain adds to the holding power of the anchor, which has been stated here already. However, I have never seen the Chief Mate stack the chain on the anchor, which has also been stated on this thread. I would say it has been done though. The procedure is usually, but not always the same, drop the anchor, pay out the scope with some tension, set the anchor and then lay the chain out, not stacked. This helps to control swing, keep the anchor down and keep it set. In my opinion, I would rather have the added weight of the chain to keep my boat in place and keep me safe then worrying about the added extra weight I am carting around. The safety of my boat, passengers and myself are more than worth the cost of fuel or maintence or whatever.
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Old 10-22-2011, 08:10 AM   #19
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RE: Do anchors scale?

I think the problem with anchors is every design is a compromise like most things in life. By design...when anchors bury and present fluke area for holding...they are very directional and the tests seem to prove that with fortress and danforth designs usually winning the straight pull tests.

Cruisers worry about swimg so quick setting comes to the top of the list of desireable traits....the jury is out on this one as most testing is not all that scientific because it's VERY hard to be without making the tests cost way more than any expected gain form the results. Another factor is whether you will be aboard or awake to monitor breaking out. A lot of fishing boats have the luxury of anchor watches and don't usually anchor for long periods in one area

The OP talked "scale"...my research has led to many discussions that at some point....scale IS important as sheer weight will become all that is necessary. Look at buoys...lots of chain and a big concrete block. Mooring mushrooms tend to be the same but the scoop deign is supposed to help but the fact that they are heavy and bury is their greatest attributes. Navy stockless are big blocks of iron with not very...but a little effective flukes...again weight of anchor and chain seems to be the ticket as can you imagine trying to break out a 50 ton danforth???

A top contender for hurricane anchoring is the 3 danforths all out at 120 degrees to one another...good holding and laying to a combo that reduces breakout tendency. But not practical for overnight / several night anchoring.

Tandem anchoring seems to be gaining favor but there is a lot of conflicting info on when it works/fails...while worth investigating...and perfecting...it will take a lot of trial and error on your part...just hope the errors are small!

So my cut on this whole anchoring thing is scope is important and moderate to heavy winds negate the catenary of all chain so scope plus anchor design and weight arethe 3 main ingredients. the newer designs have improved on holding power while increasing the chance of reburying quickly...just the natural progression of building a better mouse trap. If you can afford the weight...then a huge bruce, delta, cqr...etc..etc will probably work as they always have. If you rarely anchor for longer than overnight and don't expect any shifts in wind/current then it almost impossible to argue against a danforth or fortress....

But if you dismiss all the different possibilities that occur for different anchoring situations and are betting your life on one anchor, one anchor design, one way of setting one or both without lot's of reading, experience and careful thought...then you might as well just use your head because it's buried PLENTY deep in the sand already!!! :-)
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Old 10-22-2011, 08:16 AM   #20
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RE: Do anchors scale?

It's been proven time and time again that chain on smaller vessels...say up to 65 feet and using up to3/8 chain...that winds 0ver 30 knots will usually lift all the chain off the bottom and by the time the winds hit 50 or so...that chain is pretty straight* and transferring shock loads to the vessel.

*

All chain I think is the way to go for simplicity and security to a degree....and it's good for typical sheltered, non-stormy situations...the argument becomes thinner when approaching storm conditions and there's the age old argument of total weight and smelly, muddy chain which many people have figured out to avaid.

This goes to the OPs question....scale IS important as what is used on ships does not transfer all the way down to most of us.* Where is the break???* I don't know.
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