Mantus rode

[skipmac]

Originally Posted by ramblinrod

Now regarding the claim that the difference between 7:1 and 10:1 is negligible.

I disagree.

While the effect of increasing scope may be a case of diminishing returns, the difference is not negligible, especially, if this difference makes the difference between the boat dragging and crashing on rocks, or staying put with the crew cozily inside awaiting the storm to pass.

First, perhaps you don't believe the math. IF the rode was a perfect, straight line from the end of the anchor shank to the bow and a perfectly flat bottom these are the angles

7:1 scope - 8.2 degree angle between the bottom and the rode.

10:1 scope - 5.7 degree angle between the bottom and the rode.

That is a difference of 2.5 degrees. You do understand how small that angle is???? If you got in the water with a protractor you couldn't practically measure an angle that small. When you factor in a real world anchor rode wind that moves the boat around and a real bottom that isn't flat like a sheet of plywood then that difference is less than negligible.

And in case you want to argue this point, the extra weight of any additional anchor chain in 10:1 scope will not make an anchor dig in any better or hold any better. It's the anchor that does that, not the chain.

Further, even if you had the biggest, heaviest anchor chain in the world and 50:1 scope so your catenary theory worked and reduced the angle down to zero the effect would still be zilch, zero, negligible.

[evm1024]

Originally Posted by Delfin

This is actually very helpful, and I understand much better now the source of your opinions from the section highlighted in red above. You apparently have or had poor anchoring technique, or perhaps poor anchors, and rather than learn the skill and to compensate, you dump out the anchor locker to make up for your inexperience or inability to do what more experienced cruisers do routinely - set an anchor, all around the world, in all conditions, safely.

By Gumby, I think you hit the nail on the head.

We see this all the time. For example when I'm teaching Telemark Skiing I spend 80% of the time trying to overcome the students bad habits that they have developed because of prior bad technique and poor equipment. They find something that appears to work but in reality is just masking the underlying cause.

I'm not saying that they are dumb but rather that equipment and knowledge is much better now. You do not have to fight the equipment to make it do what you want. My first recommendation is to rent some new skis... (upgrade your equipement) And I should add thay they fight tooth and nail and only give up the bad habits with great difficulty. The reward is their big smiles once they do.

The same can be said for anyone who still has a CQR and perhaps a Bruce hanging off their bow.

Modern anchors have pretty much removed the need for different types of anchors for different bottoms that were the norm when many of us learned. You needed different anchors to overcome the deficiencies of prior generations of anchors.

Having 2 different anchors on the bow came about by this need for different anchors and thus the rode on each anchor was often half of the total rode carried. This "short" rode limited the depth that an "old school" sailor could anchor in. Thus they did not get any experience in deeper anchorages and were always anchoring with scope fixated in their mind.

And so a bunch of compensatory habits were formed that became ingrained. Their (anchoring) world was defined not by knowledge and learning but dead ends in learning.

[hpeer]

Originally Posted by Delfin

I think the 6#/ton is a rule of thumb that probably makes some sense for smaller boats, but doesn't apply when the anchor gets heavy enough. Delfin stays put in most any kind of a blow with 4:1 scope and 176# for a 64 ton boat, and a 384# hook would be more than a bit of overkill, nevermind not fitting.

What hasn't been discussed (that I noticed at any rate) is the importance of snub lines in any anchoring system. I can never remember the formula, but I believe that it is true that if the force on the anchor is dissipated over 4 feet via a stretching snubber, the force is reduced to 25% of what it is if the rode comes up short without the snubber. You could dissipate the force of impact to the ground to near zero of a tank dropped from a building with an appropriate rubber band.

So, IMO, when you talk about ideal scope, the conversation is somewhat meaningless without a discussion of the entire anchor system, including the snubber.

Delfin,

I agree, it’s not linear. To my mind there should almost be some minimum weight anchor, probably minimum weight depending upon anchor style. As a youngster working out of 14’ boats, we bad minimal anchors, Danforth type. Sometimes they would drag because the points would not penetrate the bottom. I would sometimes try to hand set the darn things. Not always successful.
I have a 15# Bruce in the dink for that reason.

There is likely some kind of rational curve of displacement vs anchor weight or surface area vs anchor weight. None of the charts I see inspire a great deal of confidence.

[skipmac]

Originally Posted by Dockhead

I use a snubber rarely, and when I do, I tie it on to the chain with a rolling hitch. I never much saw the point in chain hooks, which introduce a risk of falling off, but YMMV.



I think it makes very good sense to attach the snubber nearer the waterline, if it's reasonably possible to do it in a strong enough way, even if it doesn't help with tuning, but it very well might. The only drawback is that I think it is much more difficult to adjust the length of the snubber, if it is attached down there. A huge advantage of attaching the snubber there is the total elimination of chafe.

I've always used a rolling hitch or a Prusik knot since I have experienced standard chain hooks falling off the chain quite easily but I know Mantus (and others) makes a chain hook type device that is supposed to work better and not fall off.

Yes the eye attachment did eliminated the chafe on the snubber completely. The only down side, you can't see the snubber line from other boats since it's mostly under water, just the loose chain hanging off the bow so people were always trying to warn him about his anchor.

[hpeer]

I have welded an eye to the bow, right under and attached to the bohstay eye, so that the reinforce in another. 1/2”. SS plate. I used it for a while but haven’t recently because it’s a bit of a PITA and it’s harder to adjust length that way.

A couple of years ago there was a snubber thread that Evans contributed to. He came up with some research on snubbers that suggested much lighter and longer snubbers than we Cruisers normally use. I’ve been using 1/2” nylon and have only had it break when ther was chafe. The point is you want the line to stretch considerably to mitigate surge forces and that can only happen if it’s light and long enough. Damn near a boat length.

As to the boat yawing, I’ve heard of folks using an rogue on the bow, or lowering ansecond anchor to scrape on the bottom.

[Delfin]

Originally Posted by skipmac

I've always used a rolling hitch or a Prusik knot since I have experienced standard chain hooks falling off the chain quite easily but I know Mantus (and others) makes a chain hook type device that is supposed to work better and not fall off.

Yes the eye attachment did eliminated the chafe on the snubber completely. The only down side, you can't see the snubber line from other boats since it's mostly under water, just the loose chain hanging off the bow so people were always trying to warn him about his anchor.

Soft shackles make attachment secure and easy, and are not the weak link in the system.

[ramblinrod]

Originally Posted by Delfin

This is actually very helpful, and I understand much better now the source of your opinions from the section highlighted in red above. You apparently have or had poor anchoring technique, or perhaps poor anchors, and rather than learn the skill and to compensate, you dump out the anchor locker to make up for your inexperience or inability to do what more experienced cruisers do routinely - set an anchor, all around the world, in all conditions, safely.

Actually, I don't believe you do understand better now.

I don't believe you really have any understanding of what I do or how I do it, as you simply don't know me, nor what you are talking about, pertaining to me, at all.

I believe the sole purpose of your post is to intentionally mislead others and to attempt to discredit without merit, the perfectly valid and accurate information that I have posted.

What a shame if you actually had something of value you could post.

I have excellent anchoring technique, proven by the number of mornings I have awoke in the same place I was anchored, and the same holds true, for all of those I have provided anchor technique training to.

I have anchors that are suitable for the conditions I anchor in. I am quite well versed on various anchor designs, and consult boaters on the advantages and disadvantages of each.

I do not "dump out the anchor locker" as you have suggested, proving that you truly do not understand my skill, ability, or practices to anchor effectively.

So I think this whole post of yours is solely for the purpose of drawing attention from the accuracy and validity of the information I posted, that does accurately reflect my opinion on this matter, and appears to contradict the thrust of your opinion, which I believe is fundamentally flawed, based on the contents of your posts that are actually about YOUR anchoring technique.

Now, another fundamental flaw, that you, and others like Dockhead have posted, is the suggestions that you can possibly predict with any accuracy all the conditions at play, that will impact the holding force of the ground tackle system for any particular circumstance.

The relevant things that a boater can know are:

1. The size and weight of the vessel.
2. The type and weight of anchor and unit length of rode.
3. The amount of scope put out.
4. A vague notion of the bottom type and contour.
5. The available weather forecast information.

The things the boater can't know are:

1. The actual bottom holding power and contour.

The former would require considerable practical testing under all of the conditions to be encountered in that specific location. Not practical in most cases for the typical, even the most expert, cruising sailor.

Notwithstanding, it is good practice to test the holding power during every anchor set, as I have instructed earlier in this thread.

A relative vague idea of the bottom contour, may be obtained from charts, which I endorse and check every time I anchor. Additionally, the bottom contour may be verified to an extent, using sonar, while scouting an anchorage, which I also endorse, and am in the process of installing a high resolution 3D sonar device on my personal vessel for this purpose. I find the value of this is a common oversight by many boaters, who believe a basic depthsounder is all that is required; the latter of course being a useful tool, but 3D sonar being vastly superior in my opinion.

2. The actual weather. Most boaters with any valid experience know that the weather can vary substantially from that personally predicted or forecast. In fact if one checks enough weather forecast sources, any given day may be fair in one, and foul in another.

Based on these very key elements, no boater can predict with precise accuracy the minimum amount of scope required.

Therefore it is my general recommendation, assuming reasonable holding, swing room and forecast conditions, to use 3:1 scope minimum for temporary holding, 5:1 scope minimum for overnight, expecting reasonably fair conditions, and 8:1 or greater in anticipation of storm conditions.

It is not surprising at all to me, that many anchoring experts concur with this advise, because quite frankly, this is where I got it from.

It is of course possible that one can use less scope, and maybe get away with it, either once or many times over their lifetime, but it only takes that once for it to be their last anchoring attempt.

And lastly, there are no true hard and fast rules about what scope must be used in all cases. But the general premise, accepted by all (well as I thought, at least until this thread), even those who participate in short scope deep water anchoring, where possible, more scope is better, within reasonable limits of course.

[Delfin]

Originally Posted by ramblinrod

Actually, I don't believe you do understand better now.

I don't believe you really have any understanding of what I do or how I do it, as you simply don't know me, nor what you are talking about, pertaining to me, at all.

I believe the sole purpose of your post is to intentionally mislead others and to attempt to discredit without merit, the perfectly valid and accurate information that I have posted.

What a shame if you actually had something of value you could post.

I have excellent anchoring technique, proven by the number of mornings I have awoke in the same place I was anchored, and the same holds true, for all of those I have provided anchor technique training to.

I have anchors that are suitable for the conditions I anchor in. I am quite well versed on various anchor designs, and consult boaters on the advantages and disadvantages of each.

I do not "dump out the anchor locker" as you have suggested, proving that you truly do not understand my skill, ability, or practices to anchor effectively.

So I think this whole post of yours is solely for the purpose of drawing attention from the accuracy and validity of the information I posted, that does accurately reflect my opinion on this matter, and appears to contradict the thrust of your opinion, which I believe is fundamentally flawed, based on the contents of your posts that are actually about YOUR anchoring technique.

Now, another fundamental flaw, that you, and others like Dockhead have posted, is the suggestions that you can possibly predict with any accuracy all the conditions at play, that will impact the holding force of the ground tackle system for any particular circumstance.

The relevant things that a boater can know are:

1. The size and weight of the vessel.
2. The type and weight of anchor and unit length of rode.
3. The amount of scope put out.
4. A vague notion of the bottom type and contour.
5. The available weather forecast information.

The things the boater can't know are:

1. The actual bottom holding power and contour.

The former would require considerable practical testing under all of the conditions to be encountered in that specific location. Not practical in most cases for the typical, even the most expert, cruising sailor.

Notwithstanding, it is good practice to test the holding power during every anchor set, as I have instructed earlier in this thread.

A relative vague idea of the bottom contour, may be obtained from charts, which I endorse and check every time I anchor. Additionally, the bottom contour may be verified to an extent, using sonar, while scouting an anchorage, which I also endorse, and am in the process of installing a high resolution 3D sonar device on my personal vessel for this purpose. I find the value of this is a common oversight by many boaters, who believe a basic depthsounder is all that is required; the latter of course being a useful tool, but 3D sonar being vastly superior in my opinion.

2. The actual weather. Most boaters with any valid experience know that the weather can very substantially from that personally predicted or forecast. In fact if one checks enough weather forecast sources, any given day may be fair in one, and foul in another.

Based on these very key elements, no boater can predict with precise accuracy the minimum amount of scope required.

Therefore it is my general recommendation, assuming reasonable holding, swing room and forecast conditions, to use 3:1 scope minimum for temporary holding, 5:1 scope minimum for overnight, expecting reasonably fair conditions, and 8:1 or greater in anticipation of storm conditions.

It is not surprising at all to me, that many anchoring experts concur with this advise, because quite frankly, this is where I got it from.

It is of course possible that one can use less scope, and maybe get away with it, either once or many times over their lifetime, but it only takes that once for it to be their last anchoring attempt.

And lastly, there are no true hard and fast rules about what scope must be used in all cases. But the general premise, accepted by all (well as I thought, at least until this thread), even those who participate in short scope deep water anchoring, where possible, more scope is better, within reasonable limits of course.

Yes, well it's more hygenic to pull up the carpets and vacuum under them as well, but nobody does it because it is of such minimal value compared to the hassle. Kind of the same with recommending 8:1 scope when better technique and knowledge would make that virtually pointless.

[hpeer]

Originally Posted by Delfin

Soft shackles make attachment secure and easy, and are not the weak link in the system.

Delfin,

Do you thread the shackle through the links or just wrap it around the links and pull on the stopper knot to lock the shackle down on the chain?

Or something else?

Maybe go around the chain twice and then pull on the shackle?

[evm1024]

Originally Posted by ramblinrod

SNIP

Therefore it is my general recommendation, assuming reasonable holding, swing room and forecast conditions, to use 3:1 scope minimum for temporary holding, 5:1 scope minimum for overnight, expecting reasonably fair conditions, and 8:1 or greater in anticipation of storm conditions.

It is not surprising at all to me, that many anchoring experts concur with this advise, because quite frankly, this is where I got it from.

SNIP

Ah, not from experience but from experts.

Given the disparaging comments you made in regards to Dashew, Smith et al. I wonder just which experts you base your opinion on.

Scope vs catenary (Rocna Knowledge Base)

Originally Posted by Peter-Smith

Catenary in deeper water

The rode's catenary effect on holding power is determined by the amount of chain and/or rope suspended between the boat and the seabed, so the need for a high ratio decreases with increasing depth, as shown in the graph below. In other words, in deep water, catenary does start to have a practical impact.

This chart is intended to illustrate an example scenario, in order to show how this relationship between depth and scope works because of catenary. It is not supposed to recommend a particular scope for a particular depth – there is no such simple conclusion, and rules of thumb are generally overly simplistic. A scope of 3:1 should normally remain the minimum. In very shallow water this minimum may be too low. Then again, if your boat is in shallow water, it is probably well sheltered. There are many variables to consider.

Someone who learned to anchor 20, 30, 40 years ago and never upgraded their knowledge and skill set to keep up with modern practices and who has spent their life anchoring in shallower waters would be very unlikely to have the experience or knowledge needed to anchor successfully in Greenland.

[ramblinrod]

Originally Posted by evm1024

By Gumby, I think you hit the nail on the head.

No, I don't think so.

I happen to be very familiar with various anchor designs and technologies.

I understand, and have considerable experience with pretty much all types of anchors.

Your arguments and statements in this regard are completely invalid.

I think this kind of stuff that your commonly engage in just demonstrates a total lack of character.

Why don't you try a new way to contribute to the forum?

Share with us what you personally know, instead of attempting to discredit and disparage others, especially referring to their knowledge level, to which you truly have no personal understanding at all.

That would be a lovely, refreshing, positive change to CF in my opinion.

[ramblinrod]

Originally Posted by evm1024

Ah, not from experience but from experts.

Incorrect.

My original knowledge came from the advice of many experts and has been supported by over 20 years of practical experience on various boats, with various anchoring systems, in various conditions.

Again, please try to contribute something useful without attempting to disparage others.

Given the disparaging comments you made in regards to Dashew, Smith et al.

This is not true.

I don't believe I have made any disparaging comments against these people.

Someone who learned to anchor 20, 30, 40 years ago and never upgraded their knowledge and skill set to keep up with modern practices and who has spent their life anchoring in shallower waters would be very unlikely to have the experience or knowledge needed to anchor successfully in Greenland

Well obviously this is completely inapplicable to me, who has been constantly upgrading knowledge and skills with respect to anchoring.

I have anchored successfully in conditions very close to those that are found in Greenland.

Again, I believe you would be much better served to share your skills and experience with us, than to attempt to disparage others, especially about things you really don't know about. Give it a try.

[Dockhead]

Originally Posted by ramblinrod

. . . I believe in fact it is substantial, and your constant advocating of the adequacy of 3:1 scope for storm conditions, regardless of water depth is contrary to safety.

I guess, for the tenth time (maybe 20th time?), I never said that. 3:1 could be adequate. It depends.

Originally Posted by Dockhead

. . . I see I need to repeat yet again, that I did not say that 3:1 is sufficient.

Once again, I said that 3:1 can be sufficient, depending on the conditions and circumstances, and especially, on the size of your anchor. I have said many times, and I don't want for there to be any doubt in anyone reading this -- the amount of scope you need varies according to a lot of different factors. Every sailor needs to know specifically how much is needed in what set of conditions. It's great to have a reserve, but when conditions don't allow it, your life may depend on your knowing how much you can get away with, so that you can make correct choices between non-ideal variants.. . .

Originally Posted by ramblinrod

Of course the more weight of chain out, the better, and by the water being deeper, requires more chain out to reach the bottom, but this does not change the fact, that holding power still increases with more scope, and in my opinion, as is supported by the geometry, physics, my experience, and the opinion of most of the anchoring experts I trust, the difference is substantial. .

Obviously you didn't pay attention to the very thorough explanation of how scope works, further up the thread.



A fetish is the "attribution of magical qualities to inanimate objects", and forms the basis of the religion of many primitive people. A fetish is a religious belief which is unconnected with logic, physics, or math. I believe that this is what we are seeing here, and the fetish with scope -- that is, the irrational belief in its all-conquering power, is the number one misconception about anchoring among inexperienced sailors. If in doubt, dump out the chain locker. It disturbs me that there is someone about taking money to perpetuate such harmful misconceptions, to be honest.


Delfin is right. But I realized this earlier -- when you recommended anchoring off a lee shore, in order to achieve greater scope. At that point, the level of knowledge we are dealing with became entirely clear to me.



* * *



What's good is that this question need not be debated like "You will go to hell if you eat pork"; "No! baptism washes away all sins!". This question is subject to being quantified.

So Rod, you've said that 10:1 scope is "vastly better, in all cases, than 3:1" -- shall we put that to the test?


Would you put your money where your mouth is -- is there any set of circumstances where you would choose to anchor with 10:1 in a bottom with medium holding, over 3:1 in excellent holding? Name them. We can quantify this.


I might opt for 10:1 with a CQR of less than ideal size, but let's suppose we have a Spade (just because I have the numbers) of at least recommended size for the boat. Let's say there will be 50 knots of wind. Take a boat of ANY SIZE, and take water of ANY DEPTH of your choice, and tell me a scenario where holding power will be greater with the 10:1 scenario, in 50 knots of wind, and we'll see how "vastly better" 10:1 is "under all circumstances".


You can do the math yourself -- all the tools have been given to you. You have shown zero interest in the math or physics of the question -- as one might expect, since religious beliefs don't require any such "overcomplication". Others of us do not feel entitled to strong opinions without doing actual work to back them up -- we read, we study, we give references, we do calculations, but those who hold their opinions like religion don't need to bother with any of that. So, let's have the quantification of the question.

[ramblinrod]

Originally Posted by Delfin

Yes, well it's more hygenic to pull up the carpets and vacuum under them as well, but nobody does it because it is of such minimal value compared to the hassle.

Actually, I believe the "modern thinking" is not to have carpets in the first place.

If you do, and don't clean under them on occasion, thanks for the heads up.

Kind of the same with recommending 8:1 scope when better technique and knowledge would make that virtually pointless.

This is the fundamental disagreement.

In my opinion, there is no better technique than to use sufficient scope to suit conditions, which on occasion can be 8:1, regardless of the anchor used (within reason), or how deep the water is.

Certainly when considering something like a mooring anchor arrangement, like a 3 tonne block of cement, 8:1 scope will not likely be required.

That's not what we are talking about here.

For an anchor from 15 to 50 kg, properly sized and suited for the boat and anchoring conditions, 8:1 scope or even more may be required for storm conditions.

BTW, I have never said this HAS to be all chain.

It most certainly could be, or it could 300 feet of chain connected to the length of nylon required, which may be stored elsewhere normally, but available in preparation for storm conditions.

If you are not prepared to deploy an 8:1 scope or more when needed, I do not consider this "modern thinking", I just consider it "reckless".

[evm1024]

Originally Posted by ramblinrod

SNIP

Why don't you try a new way to contribute to the forum?

SNIP!

It is much harder to change someone else, than it is to change yourself. Don't you think?

Why don't you try a new way to contribute to the forum? That would be a lovely, refreshing, positive change to CF in my opinion.

I agree - See above.

Anyone can post on the internet pretty much anything that they want. We as readers have to read their words and make a "guess" as to how useful their words are.

One way to get a feel for the usefulness of their words is to see if their words and their actions are inline.

I have a very hard time thinking that someone with a CQR for example on their bow has kept up to date with anchor technology. But then again that is just me. It does not mean that they are "wrong" but rather that their opinions are likely out of date. I do recommend that they upgrade their ground tackle and to get any latest generation anchor and dump the CQR.

Most on this thread are attempting to understand the hows and whys of anchoring technique especially in adverse situations. Whereas you (OMHO) appear to be defending an entrenched position that others disagreed with.

In terms of contributing to this thread I refer you again to your own post quoted above.