Anchor Chum

[MedMan]

Re: Boy oh Boy ....

Q.E.D. Agreed also.

Hylas! You are clearly an enthusiast, some might say a fanatic. I surmise that you formed your ideas some time ago based upon a partial understanding of the subject and, having nailed your colours to the mast so emphatically, cannot now face the prospect that you may actually have been wrong from the beginning. You would do well to learn that Mathematics is an exremely useful servant but a tyranical master.

Still, you have at least admitted that your theories only apply in 40 knots of wind or more. Let us just hope that you remember that and don't go jumping into threads any more with sweeping statements that simply do not apply to the case in question. Let us hope also that you learn to place a greater emphasis on observation and come to realise the value of the cumulative experience of those who contribute to this forum.

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[hylas]

Re: some answers

Dear nigel_luther

16kgs anchor on a 14 ton boat ........ that is same weight as I carry on 3 tonner.

And you are right.. but to be honnest, I should tell you that the 16 kg steel anchor I have on my own boat would have more than twice the surface area of yours.
(1510 sq cm). again my theory of holding related to surface area, not to weight..

And like you, this is my main anchor I use for all anchorings.. But unlike you, I don’t have any house or flat.. and all my belongings are my boat and what I have in it (her).. and that’s why a SAFE anchoring is so important for me..

To be also honest with you.. on this thread, I’m also provoking and I should also apologize.. but it amuse me to see that people are talking about things (chum) and they don’t know for which purpose, how it works and where to install it on the rode..

Yes it is safe to anchor on an all chain rode.. but MUCH SAFER to insert any kind of “elasticity” in the line (at least 10 meters of Nylon rope..) and a rode made of some length of chain and a Nylon rode directly spliced onto the chain will be more light and more efficient.

Yes a chum will (SLIGHTLY) increase the holding of one anchor, (but again where on the line??) but it will be more efficient and by far more easy to let go the same weight of chain..

At first I made my own observations and after quite a large experience of anchoring I meet a (now) good friend who explain me, using mathematics, the reasons of my observations..

I don’t know the company you are talking about “Titan” and the purpose they use the rope is different than anchoring.. for pleasure boats, the weight of the anchoring rope is nothing.. but one characteristic is very important: ELASTICITY

The problem of merchand ships is quite different..and I have NO experience with them.. I’m very surprise to see them anchored with very poor anchors (NavyStockless, Hall, Poole and others..) and as you said, perhaps this is a question of anchor holding a long heavy chain, which in turn holds the boat.. but this is a different story..

On our boats, we don’t like to have too much weight on the bow.. and we are lifting the ground tackle by hand or with a rather small windlass and we need anchors which hold the boat, not the rode..

I’m not sailing in drying areas.. but in “warm” waters and as frequently as I can, I dive to check my anchor and mostly to see what happens to the anchor of others boats.. I did exactly the same observations as you: “Most anchors are not dug in, and I also it’s easy to see the line of drag.. “ and they are all the time the same brands that are not dug in and also the same that are.. Therefor I did draw my own setting theory..

And chain or rope, one anchor well dug in will hold the boat..

Unless you, I’m not always satisfied with old theories.. and when somebody explain me a new theory, I’m always curious to listen to it and to try to understand..

I’m not automaticaly satisfied with “practice based on sound and accepted practices” and I strongly believe in mathematics.. (but unfortunately, nobody has been talking about mathematics on this thread, or better said “using” mathematics)

About your last question, where to find a chum?? They are several brand commercialy availables.. but the simplest one would be to take a large steel pot and to fill it with melted lead..

“Read his post and you see he uses 25 mtrs of chain ......... so now I question the all rope rode statement made earlier .......”

But sorry, you didn’t read my post.. otherwise you would not have asked the question.. and this is perhaps the reason why you don’t understand my theories..
I use the chain, not for the weight.. but for the anti-chafe characteristics of the chain which are by far better that the one of the rope..

I realy LOVE your explanations.. “ I have seen a 12mm mooring rope DOUBLED on my boat break in strong wind” Oh yes.. of course. The strenght of a 12 mm rope is about 2400 daN, but I will be curious to learn how you double it??
Any rope that will make a sharp bend will loose about half of its strenght.. so the breaking force was only about 1200 daN.. When testing a THREE kg anchor prototype with the National Engineering School of Monastir, I had the same problem, the 2400 daN rope break out several times around 1200 daN.. and always at the level of the bent..

I don’t know the size of your boat.. but a 8 mm chain has a breaking strenght of 3200 daN.. 1200 daN was much to weak..

But don’t bother.. I’m not trying to convince you any longer..

MainlySteam

Yes, I agree with you, we are not talking about the same thing.. that’s why we will not find any agreement..

I said that with strong winds, the chain will NEARLY have the same pulling angle than a rope of the same length… and that’s why I say that SCOPE is more important than weight.. and that will be the case with Force 9..

I never said that “I do not think it is inappropriate to keep anchor watches” Like you, with more than Force 7, I keep electronic anchor watches, both with the deep sounder and with the GPS.. so I will be pleased to pursuing further discussion with you on anchoring. and mostly I would be so pleased to learn about the subject of this thread:

- what is the purpose of a Chum and where on the rode I should install it??

And I also have to apologize if my poor experience is much less than the others that have posted….

Alain

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[Guest]

Re: some answers

HYLAS ..... 1) You wrongly attribute a few comments to me ..... from other postees actually - >
About your last question, where to find a chum?? They are several brand commercialy availables.. but the simplest one would be to take a large steel pot and to fill it with melted lead..

as example ...

But anyway .... a) Merchant ships anchors are based on Admiralty Cast Pattern ...... and if you check your data - you will find that the admiralty required a pattern achor design to meet certain criteria and they also tested all manner of designs to ascertain the best - the Cast Pattern resulted is now almost universal on ships. Albeit with slight variations in flukes but basically the same - so bang goes that one.

b) Doubling moorings is NOT passing a rope around something and back to the boat etc. I have been a seaman for many a year and would not be so crass stupid. The moorings were actually made of with good sound mooring hitches BEFORE passing back to the boat. Doubling a rope or mooring is to pass 2 ropes for the one job. Check your seamans dictionary. I used 1 rope to do the job safely and seamanly.

c) <chum> and they don’t know for which purpose, how it works and where to install it on the rode..
Boy oh Boy you say I don't read the posts ...... this has been answered so many times and you have ignored them .....

Now reading through yopur threads ....... I wish I could condense them down to relevant sections instead of the long prose ..... but the emphasis has changed as each one posted from all-rope rode to also chain rodes included ..... make your mind up ..... chain or no chain ??????? I have no argument with mixed rodes - I don't like them, but also appreciate why people use and like them .... many points that you made about lightness etc. are true ...... but I still disagree with the better holding theory ...... you say that the 16kgs anchor holds you well with rope and elasticity .... OK, I'll try this even though you'll not think about it or believe me !!!! What length of chain would constitute another 16kgs ?? What relative weight would that chain be in water ?? Now how much rope to reproduce that same 16kgs ?? And what weight that rope in water ?? You say yourself that extra weight adds to the anchor holding ...... so why not put it into a non-chafeing, strong and damping chain ????? which will actually reduce the rode necessary to lie safely ?????

HYLAS ----- yes we will disagree, basically because I listen to others who I am convinced AFTER Listening to them that they may have a point and may know more about something than I. I do not disallow anyone wiothout fair crack at explaining why etc. I also listen to crackpots and misguided morons...... BUT please I don't put you in either of those categorys - I put you in the category of self-convinced expert.

I am a Professional Surveyor by Profession, owning and running a very succesful Marine Survey Business - I have even passed your reasoning and maths onto various 'experts' in my profession ..... and one actually summed it up very well ..... and I will not repeat it as I do not want to create an international incident ....... needless to say they were not too convinced about your foundation, your reasoning ........ they'll stick with chain I think !!!!

I think a bit of Humility and stop trying to ram it down everyones PC ....... the thread has been interesting battle - but it must come to an end as I do not want to get into repetition as you seem to like to do.

I wish you fair winds and peaceful achorages and hope that Panteniaous understands your Maths !!!


<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[Guest]

I forgot .....

If you dragged anchor and fell upon rocks / hard and boat was damaged resulting in a claim. AND I was appointed to inspect the boat for the insurance company.....

If I found after studying weather reports and the circumstances of the graounding / foundering ...... and it included an all or majority rope rode insufficient to hold the boat in my honest opinion ......... would I be unfair in declaring that to the Insurance Company.

Now if I was appointed by the boat owner - I would have a problem as I would observe a condition considered professionally as unsuitable .... what am I supposed to do ????

Take Care HYLAS - you are in very uncomfortable ground with this ....... and I think an Insurance Co.may not appreciate what they consider an undue risk.............

I do not say this is absolute fact - probably an untried one - but still a distinct possibility all the same.


<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[hylas]

Re: I forgot .....

nigel_luther

"I actually take offence now as you have made claim that many dispute 'my old beliefs'

But Nigel.. I have only returned YOUR phrase to you..

You have related various experiences. But I can also do the same. For example Earl Hinz, the “Gourou” of Anchoring in U.S.A.. in his well known book “The complete book of anchoring and mooring” says:
“Chain proved to be far less effective as a means of securing achorages than did Nylon anchor rode”
“To use an all-chain in a heavy blow, you must include an ELASTIC riding stopper.. “
“As the wind load on the boat further increases, the chain is lifted completely off the bottom.. As the wind load increases even further, the catenary tends to disappear.. virtually eliminating the shock-absorbing feature claimed for the chain. and also increasing the lead angle of the anchor shank.. “
ETC..

And when not only I repeat the same things AND I prove them with mathematical formulaes.. Your only answer is “Various practical experiences have been related to you but you still persist in defining laws of nature with mathematics ....”

You don’t trust Mathematics.. and you only listen to people who have the same beliefs than you.. and you will be offensed if I will call that “CONSERVATISME..”

Sorry I don’t find another argument to convince you.. and I don’t think I will.. but I hope most of my explanations have been reed by others and that I have convinced.. or at least I have underlined the question.. to some others..

As you can also realise, I have not stated or made anything that majority disagree with.. two or three contradictors on this forum doesn’t mean “majority”. More and more people are following what you call “my theory” and what I call “Modern theory of anchoring..”

Back to the “chum”. No I haven’t been told that the chum should be placed at about mid depth of water.. I only get one answer.. ½ or ¼ of the length.. wich is rather unprecise.. either concerning the position as the effect of the chum.. catenary, holding, swinging circle..

You also tell me that “ placing the chum at the shank does nothing except effectively increasing the weight of the anchor”

Curiously, You are once more AGAINST the mathematical laws..

There is no simple equation of the result, but if we assume the scope is greater than 3:1, an acceptable approximation (with less than 6% error) is given by:

Fk is approximatively egual to Fc + K x (Lk /H) = Fc+ KN x ( Lk/L)

These expressions show the improvement equals the chum weight K multiplied by the ratio Lk/H. Consequently, the best improvement is obtained by putting the chum NEAR THE ANCHOR, where it equals the chum weight K multiplied by the scope N.

With the same chum in the middle of the rode, the holding improvement would be halved.

And you can again say what ever you want about mathematics or experience.. but sorry, YOU ARE WRONG..

MedMan

I will not discuss the fact that I’m an enthusiast.. I have to be, for spending so much time trying to convince people when I know right I the beginning that I will NEVER succeed..

Following your comments, Earl Hinz is wrong, Alain Fraysse (a French anchoring expert) is wrong.. mathematics are wrong.. (and also I’m wrong and many others..) but you haven’t be able to demontrate that or why WE are wrong..
your ONLY argument to defend YOUR theories is the “cumulative experience of those who contribute to this forum”.. and you are only talking about less than one hand full of conservative people who didn’t proove anything against these modern theories..

Earl Hinz is very well known all over the world; Alain Fraysse is very well known in France (at least) and, sorry for that, but I’m also quite well known in this field..

What are the references of “those experienced people who contribute to this forum”???

And as you will not have any more SCIENTIFIC arguments to oppose to these modern theories.. this will close this thread..

I only hope that all these discussions will have open the eyes of most of the non participating people who have read this exchange of ideas..

And I apologize, but the Earth is ROUND..


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[duncan]

Re: the earth is round?.........

Can we please please start another thread if anyone want's to take this up!
Given the inability for people to agree on the value of a nautical mile or the ability of GPS to deliver an accurate SOG it could be a long one...........

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[Gunfleet]

is that...

Earl 'fatha' Hinz? We saw him at Ronnie Scott's in the 70s.

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[qsiv]

Re: I forgot .....

<<You also tell me that “ placing the chum at the shank does nothing except effectively increasing the weight of the anchor”

Curiously, You are once more AGAINST the mathematical laws..

There is no simple equation of the result, but if we assume the scope is greater than 3:1, an acceptable approximation (with less than 6% error) is given by:

Fk is approximatively egual to Fc + K x (Lk /H) = Fc+ KN x ( Lk/L)>>

Oh dear the danger of reading formulae without considering the real world, and then applying the formula out of context.

The catenary formed by an anchor cable is can be considered to be a 'standard' engineering catenary with one end displaced below the other. This changes the shape of the catenary slightly. Consider a standard horizontal catenary and establish the force required to maintain steady state. Now add a signidicant weight at one anchor point, and reasses the steady state force to maintain the same midpoint deflection. Now add the weight to the centre of the catenary, and reasses the force required to bring the midpoint deflection back to the original position. The second case will require a significantly greater force.

As for my calculations of wind forces against flat plane objects - you can find them in many engineering books, even structural engineering reference books. Mine came out of my University books on Aerodynamics and Hydrodynamics- I read Naval Architecture at Southampton, and not surprisingly thes sort of topics were a significant element. If you need the finite element analysis of catenary curves I still have the source code (somewhere) of second year computing project - which I had rather hoped I would never need to look at again!

I'm also concerned that through the thread there is an assumption of 3:1 scope for chain - and then we go and talk about anchoring in 60 knot winds. I for one would have rather more scope under such conditions - and I'm not too sure that I would be lying to a single anchor in winds that will be gusting well into hurricane force (F12)

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