If you like to know the anchor load and minimal chain length... here is the tool to do it...

[MathiasW]

So, thanks so far for all the constructive feedback received.

Actions taken so far:
- Made kp the default unit, rather than daN, which seems to be alien to too many people. But remember, one can select between daN, kp, lbf with the toggles in the top right corner. (Note, I use lbf rather than lbs, since lbs refers to masses, and lbf to forces...)
- Changed 'Vessel velocity' to 'Vessel velocity @ anchor', to make it clearer it is a residual velocity as the vessel is moving at anchor. It is not its normal speed or anything like that.

To see these changes, the page needs to be reloaded.

Actions to be taken:
- Make the default unit dependent on which country the calling browser is coming from. So, UK, Ireland, US, OZ, NZ I would make the default to lbf/lbs, and for the rest it would be kp. And the youngsters will have to switch to daN themselves.
- Waiting for more detailed information about the results in Basic Mode that were claimed to be too high.

If you believe my choice of feet/pound countries is wrong or incomplete, let me know...

Cheers

Mathias

 

[NormanS]

Sure! It is not precise, as Jonathan already hinted at, but if you have your chart plotter running at anchor for a while and watch the Speed over Ground arrows pointing here and there in all directions, then watch for how large the velocity gets when the vessel is moving away from the anchor. Mathematically, it is the velocity component pointing away from the anchor that matters. Not pointing towards it, neither sideway. Only the velocity component really stretching the chain is what matters.

This figure may only be accurate to some 50%, so add some margin to what you see. Better to be on the safe side.

Cheers, Mathias

No wonder people like me are confused. What you're saying is that before I can use your formulae to decide how much chain and snubber I require, I need to be anchored for a while already. ??

And even then the figure may only be "accurate" to 50%. Well, thanks!

 

[pandos]

So, thanks so far for all the constructive feedback received.

Actions taken so far:
- Made kp the default unit, rather than daN, which seems to be alien to too many people. But remember, one can select between daN, kp, lbf with the toggles in the top right corner. (Note, I use lbf rather than lbs, since lbs refers to masses, and lbf to forces...)
- Changed 'Vessel velocity' to 'Vessel velocity @ anchor', to make it clearer it is a residual velocity as the vessel is moving at anchor. It is not its normal speed or anything like that.

To see these changes, the page needs to be reloaded.

Actions to be taken:
- Make the default unit dependent on which country the calling browser is coming from. So, UK, Ireland, US, OZ, NZ I would make the default to lbf/lbs, and for the rest it would be kp. And the youngsters will have to switch to daN themselves.
- Waiting for more detailed information about the results in Basic Mode that were claimed to be too high.

If you believe my choice of feet/pound countries is wrong or incomplete, let me know...

Cheers

Mathias

Ireland is a metric country...and has been since I was a small boy...?...1971...AFAIK.

 

[MathiasW]

No wonder people like me are confused. What you're saying is that before I can use your formulae to decide how much chain and snubber I require, I need to be anchored for a while already. ??

And even then the figure may only be "accurate" to 50%. Well, thanks!

The figure on your vessel velocity may only be accurate to 50%, but this does not imply at all that the chain length or anchor load will only be accurate to 50%.

And compared to the rule '3:1 scope' or '7:1 scope', I dare to maintain that my results are still ever so slightly more accurate and meaningful.

In any case, the tool allows you to play around with different scenarios and this way one can get an impression what better to avoid at anchor, and what is ok. For a beginner quite useful, I believe. After having spent so much time on modelling the anchor chain I have to say that my anchoring in my early years was quite daring, at times. Why should a new-comer have to go through that?

Not that my tool is anywhere near as fancy or sophisticated as a flight simulator, but I think we all are more than happy that pilots do training on flight simulators, and continue to do so during their professional career when new airplanes come out.

Cheers, Mathias

 

[pandos]

Commercial operation? What do you mean? This is a free tool, so where is the commerce, please???? I have spent far in excess of 1000 hours on this topic and if this were a commercial operation, my business would have long gone belly up.

My motivation is to help folks anchor more safely. Some appreciate this, others do not. But frankly, I fail to understand why some are trying to piss down my back for trying to help others!

The information buttons you have been asking for are all in the commercial app for Apple and Android. You just need to pay for them. This is a LITE version, and LITE means free, but less functionality.

So is the feedback not used in the commercial App that you referred to.?

No one is pissing up your back, but if you think you might not like feedback you probably should not invite it.

 

[MathiasW]

Ireland is a metric country...and has been since I was a small boy...?...1971...AFAIK.

Excellent, I thought so, but was not sure anymore after the strong pushback seen here and elsewhere.

I am not sure about OZ and NZ either...

Officially, there are only three countries in the world that still use imperial units, USA, Liberia, and Myanmar:

Infographic: Only Three Countries in the World (Officially) Still Use the Imperial System

Imperial units - Wikipedia

 

[MathiasW]

So is the feedback not used in the commercial App that you referred to.?

No one is pissing up your back, but if you think you might not like feedback you probably should not invite it.

No, the info buttons are in the commercial version already for a year, way before this feedback was made. So, common notion of causality has it that this feedback did not have any impact on the commercial version.

And no again, I did not ask for just any, useless or rude feedback. I know I have to put up with some jerks, yes, but I reserve the right to shoot back then. That is ok for me.

 

[Tradewinds]

I know I have to put up with some jerks,

Bit rude Mathias.

 

[pandos]

No, the info buttons are in the commercial version already for a year, way before this feedback was made. So, common notion of causality has it that this feedback did not have any impact on the commercial version.

And no again, I did not ask for just any, useless or rude feedback. I know I have to put up with some jerks, yes, but I reserve the right to shoot back then. That is ok for me.

Maybe it's a language issue, but you come across as very rude. Do you really think I know how long ago you developed the commercial app? Or that you will not improve it using the feedback obtained here.

You asked for feedback on something that had obvious flaws, show some respect to those that took the time and trouble to respond, even if you did not like what they said.

 

[MathiasW]

Bit rude Mathias.

Yes, I know. There is a German saying along the lines... The echo comes back exactly as you had shouted into the woods in the first place.

 

[MathiasW]

Maybe it's a language issue, but you come across as very rude. Do you really think I know how long ago you developed the commercial app? Or that you will not improve it using the feedback obtained here.

You asked for feedback on something that had obvious flaws, show some respect to those that took the time and trouble to respond, even if you did not like what they said.

Well, you made a claim that is simply not correct. I do not expect you to know anything about the app, far from it. But if you do not know about the developments in the app, you should not make any claims about it. That is plainly rude.

I show respect to all feedback that is reasonable, and even beyond that. But somebody responding in a very mean or derogatory way, I do not think I need to show any respect at all, really. Asking for feedback is not a free ticket for others to be mean.

Back then my colleagues in the UK always said, Mathias, you can operate in British Mode and in German Tank Mode. Well, if somebody pushes the wrong button, German Tank Mode it is, I am afraid.

And btw - I have not heard of any obvious flaws in the tool yet. It does not model reality to 100%, fair enough, as it is based on a simplified model, but this is a standard approach in science and not a flaw. One can certainly try to make the tool more intuitive - yes, I very much hope so - but I have not seen any response that showed a flaw. If somebody states the tool did not work for him/her, or it did not give the expected results - without details of what parameters were used, then that is a pity, but I cannot help it. For instance, if somebody puts in a vessel length of 0 metres by accident, the anchor load will be zero. I guess almost everybody having had a problem did not read the manual. Don't get me wrong. That is very ok not to read the manual, but it should be factored in when responding. The more complex a tool is, the more knowledge is required to use it correctly.

As said before, with this tool I am trying to help the community. I do not need the money earned by the professional version. I have all that I need, but the professional version should at least pay for the annual app store fees that I need to cough up - as well as the annual server fees for the free LITE version. However, I do expect people when they respond to be respectful and say something critical, but always appreciative of my work. And this did not happen in this thread with some of the responses.

Call me Primadonna (you would not be the first ), but...

Many, many years ago I learned at school that the British have the following sandwich approach when wanting to express some criticism: 1) start with something nice, 2) make your criticism, 3) end with something nice.

This simply did not happen here in some responses. I am afraid, proper manners can only be demanded if proper manners were exercised to begin with.

But I am digressing. What I really want is useful feedback how to make this tool more intuitive and more useful for the community! Thank you!

Cheers, Mathias

 

[MathiasW]

I prefer to have a graph over a spot value. see this.

Thanks for providing this link (Graph Anchor Rode Length versus Depth), I had not seen it initially.

I will add it to my long essay on anchor chains.

Beware, though, that this calculator does not include swell, nor the effect of a snubber. So, in particular in shallow water with stronger swell, it will give quite erroneous results and will make a chain look much better than it actually is in such a situation.

And it does not work in feet and pound...

Cheers, Mathias

 

[Skylark]

Well, there is indeed a lot of garbage in and garbage out on forums like this...


After all, at most sailing schools, they do not teach about anchoring.

Oh the irony ???

My “go-to” reference on this subject usually starts with the Admiralty Manual of Seamanship. These publications regularly appear on well known auction sites for just a few pounds. Volume 2 covers “Seamanship” and Chapter 9 is dedicated to “Anchors, Cables and Anchor Work”. Of course, it’s not aimed at recreational sailing vessels but it gives an awful lot of thought-provoking information.

 

[Skylark]

Who's being rude?

You were, Tim, as well you know ?

How would you feel if you had invested time and effort and has some of the less than complimentary comments on this thread?

If it had any validity, I would have taken it on board with humility. If it didn’t, I simply would have ignored it.

It’s a strange world where universal approval of one’s work, regardless of content, is the required norm.

 

[geem]

You were, Tim, as well you know ?


If it had any validity, I would have taken it on board with humility. If it didn’t, I simply would have ignored it.

It’s a strange world where universal approval of one’s work, regardless of content, is the required norm.

Are you now the moderator?

 

[zoidberg]

Ireland is a metric country...and has been since I was a small boy...?...1971...AFAIK.

Come, come! We all know about the 'Irish mile' - and just try ordering 16 fl.oz. of Murphy's down in Buckleys' Bar !

 

[[70521]]

Good to see that @MathiasW is doing something in the anchor modeling space.

For me it is too precise and I do have a professional engineering qualification. I am very much of the old school. Chuck Place the anchor on the sea bed and payout the selected scope for the depth then add a snubber. Following @Neeves 's comments a few years ago this is attached to the cleats on the transom and run forward for a bit of spring. I chuckle to myself and always think of the scene from one of Crocodile Dundee films when Dundee says, 'now this is a knife', and think of @Neeves saying, 'now this is a snubber'.

I once crewed on a boat that was skippered by a ex-racer, we arrived at the destination and the skipper was unable to get a marina berth. So we anchored. On attempting to set the anchor it refused. After the fourth attempt I enquired of the depth of water and was a tad surprised that a extremely experienced chap had calculated the scope on the charted depth when we had almost another five meters under the keel. An extra 20 meters of chain and the anchor bit first time and did not move for three days. Later in the pub, he admitted that he never anchored. It is a skill that needs practice.

 

[pandos]

Come, come! We all know about the 'Irish mile' - and just try ordering 16 fl.oz. of Murphy's down in Buckleys' Bar !

Engineering and physics in this country are all done in metric, I am pretty sure neither of my children have any idea about imperial units..(both are engineers)

Pints are pints and thankfully still sold in Pint glasses..

I think if you asked for 16oz in Buckley's you'd get a pint, or if you ask for 556mls or 20fluid ounces which is an imperial pint, or even just a Murphy's...you'd get the same...

Not sure what an Irish mile is?.

 

[pandos]

I prefer to have a graph over a spot value. see this.

That seems an excellent resource.
What is that site?

 

[jdc]

...What is that site?

Awelina of Sweden Welcome Page

It's just some stuff I've made for myself, but put there in case useful to anyone else. All programs can run locally, ie once saved locally don't need an internet connection.