Inaccurate RYA Teaching : CTS - Quest For a New Method

[goboatingnow]

Originally Posted by Seaworthy Lass

Dave, the whole thrust of this discussion is to try and make an improvement to the RYA method of teaching CTS. I do not have anything against the RYA, personal or otherwise. Their name is mentioned constantly as the method under discussion is their's.

I have not once said anything rude or derogatory about the RYA. They are a wonderful organisation. They are not however, "infallible" as you have told me when I dared to voice the opinion their method was just an approximation rather than "mathematically precise" as you have kept repeating.

I have taken a few pot shots at you only because you have said some ridiculous things in other threads while constantly telling me how confused I was and how flawed my method is. I have avoid further discussions with you as you tend to make them very heated and I would prefer not to engage in this manner.

Im not making them heated, ive asked simple questions

(a) Could someone actually prove that either method is better or worse with reference to tide assumptions

- what do I get , more diagrams using ones own assumptions, to prove ones own assumptions, you have repeatedly avoided this issue.


(b) The RYA method is mathematically precise, it may not be mathematically accurate, The exact same questions can be said of your method, Yours is also an approximation


(c) If you really want to improve the RYAs method of teaching , why not carry out the discussion with them. what does banging on about them on these threads do -


You know Seaworthy , I have not engaged in any heated discussion, you have persisted in saying things like ( 30 degree of error) , repeatedly applied the RYA method , half heartidy to show it up or picked bizarre ( and in real life unsafe) data, which isnt derived from any real life source.

Yet all you can do if repeatidly refer to a "hovercraft" post mearly 1000 posts ago,


Debate the issues , not the RYA, if want to bang on about the RYA , surely taking to them is better, next best to that is hang out where there are lots of RYA instructors. ( maybe they might all agree with you).

You basic argument is "your" method is better , yet no real life proof has been advanced and you simply engage in mis-information and picking pieces of the issues to mis-inform.

Deal with the substantive issues,

whats heated about this I dont know, maybe you just dont like people not agreeing with you , several here have voiced their opinions , yet they are short down with all sorts of anti-RYA ranting.


and Seaworthy , yes you have a thing about the RYA, look at the title of this post "inaccurate RYA", yet you have advanced no proof , merely an application of tide assumptions thats differs from them.

dave

[HappySeagull]

Constructing a Logical Argument

[Seaworthy Lass]

Originally Posted by HappySeagull

agree, G'B'N'.
SWL, I'm not sure why the RYA seems to be your punching bag...

They are teaching a technique that is flawed and could be improved. It is a technique that has been adopted internationally. I am encountering complete resistance having it acknowledged that there is anything wrong with their method (up until relatively recently in this discussion their method was touted as being "mathematically perfect") or that it could be easily improved, or at the very least that students should warned about its deficiencies.

Even a very basic simple improvement of arcing off towards the destination rather than the rhumb line would be a huge improvement, let alone considering the last partial hour of actual current data (in some cases the latter produces relatively minor errors compared to the former).

Originally Posted by HappySeagull

the enlightened masses of twisted and deformed RYA graduates are any way not going to pick up their winch handles as a mob behind you,their Liberator, and storm the RYA Bastille in frenzied revenge ....

LOL, no I gave up all hope of this weeks ago. It is just a lone lassie standing up to the "infallible" organisation now and I am getting lots of pecking from all quarters in the process .
Is it surprising I occasionally lose my sense of humour and peck back?
I think I have been mostly very polite throughout all these discussions.

[goboatingnow]

They are teaching a technique that is flawed and could be improved. It is a technique that has been adopted internationally. I am encountering complete resistance having it acknowledged that there is anything wrong with their method (up until relatively recently in this discussion their method was touted as being "mathematically perfect") or that it could be easily improved, or at the very least that students should warned about its deficiencies.

Even a very basic simple improvement of arcing off towards the destination rather than the rhumb line would be a huge improvement, let alone considering the last partial hour of actual current data (in some cases the latter produces relatively minor errors compared to the former).

No this is a complete mis-iterpretation.

The RYA plots hourly tidal vectors, based on its underlying assumption of tide movements are overall accuracy of the data, it says the same CTS gets you to your destination.

Nobody isnt saying that that method may have inaccuracies However neither have you advanced any proof that your method is actually better. You cant prove accuracy by taking your own data and its assumptions and then showing your right, all that does it show you can do maths.

The fact is again and again the RYA provides acceptable results in normal conditions using typical interpolated real data. Arguments about the last 10 or 15 minutes are really completely ridiculous in the face of real life.

The reality is that sailing on multi hourly computed CTSs has not been tested against reality in either case. Until that is done, this is just a theory argument

This is a point you fail to realise and its the key fact in whether any method is useful

Dave

[goboatingnow]

Even a very basic simple improvement of arcing off towards the destination rather than the rhumb line would be a huge improvement, let alone considering the last partial hour of actual current data (in some cases the latter produces relatively minor errors compared to the former).

why it produces no actual real life improvement when one adds in the variability of the tide data, If D is 15 minutes before B who cares, if its 10 minutes after , who cares, just drive between the pier heads!!

[HappySeagull]

...on SWL's account (and I am partly re-iterating GoBoatingNow,lodesman and others who have said as much I think)
SWL has defended her argument. It has not been shown to be wrong. It has not been challenged as non-working for the task defined: Multiple currents,single boat speed-compute a single CTS.
Given the RYA method includes a single CTS for a sum of multiple of current scenarios, it's fair game as a comparison.

But,I opine, if an argument requires a scenario found only in Jupiter's red dot, it is unfair to compare with the RYA method.
That said, if you need a way to combine currents when boat speed is sometimes less than Drift, SWL method works, while the ( as- first- presented )RYA method , does not.
The opinion that it's not useful to go out when boat speed is less than current, is an opinion.The opinion that a close counts is also an opinion.

I agree with these opinions, mostly, but they are not the argument. I appreciate the impetus to consider the argument.

[Seaworthy Lass]

Originally Posted by Seaworthy Lass

Even a very basic simple improvement of arcing off towards the destination rather than the rhumb line would be a huge improvement, let alone considering the last partial hour of actual current data (in some cases the latter produces relatively minor errors compared to the former).

Originally Posted by goboatingnow

why it produces no actual real life improvement when one adds in the variability of the tide data, If D is 15 minutes before B who cares, if its 10 minutes after , who cares, just drive between the pier heads!!

Had the RYA method simply arced off the 'distance displaced by boat speed' vector towards the destination instead of the rhumb line, it would have given a CTS result within a few degrees instead of being more than 20 degrees in error for the example given in post #772. And that is without even taking into account the actual tidal data for the last partial hour.

[jackdale]

In some respects I am reminded that while Newton's laws work in our visible world, they do not work at the sub-atomic or cosmic level.

Are we going to apply string theory to navigation?

Given a 5 step model to use and teach versus an 11 step model, I will go with the 5 step model. That is a significant advantage.

[jackdale]

Some time should be spent understanding vectors.

Vectors: Motion and Forces in Two Dimensions - Table of Contents

In particular:

Representing the Magnitude of a Vector
The magnitude of a vector in a scaled vector diagram is depicted by the length of the arrow. The arrow is drawn a precise length in accordance with a chosen scale.

A section on the application to aircraft and boats.

http://www.physicsclassroom.com/class/vectors/u3l1f.cfm

That is why the vector line from the head of the current vector line is the boat speed.

The discussion that might ensue from the the vectoring associated with true wind, apparent wind and boat speed is going to be interesting.

[HappySeagull]

Originally Posted by Seaworthy Lass

....
LOL, no I gave up all hope of this weeks ago. It is just a lone lassie standing up to the "infallible" organisation now and I am getting lots of pecking from all quarters in the process .
Is it surprising I occasionally lose my sense of humour and peck back?
I think I have been mostly very polite throughout all these discussions.

()
well, now, perhaps you can be Joan of Arc? -though just a sense of humour would not have helped her.

[Seaworthy Lass]

Originally Posted by jackdale

In some respects I am reminded that while Newton's laws work in our visible world, they do not work at the sub-atomic or cosmic level.
Are we going to apply string theory to navigation?

If course not LOL, the M-theory would work better (very appropriately for CTS calculations it is an eleven dimensional theory). .

Originally Posted by jackdale

Given a 5 step model to use and teach versus an 11 step model, I will go with the 5 step model. That is a significant advantage.

Continue with your 5 step model then, but why not at least consider arcing off towards B instead of the rhumb line to instantly improve accuracy without adding any more steps?

[Seaworthy Lass]

Originally Posted by HappySeagull

()
well, now, perhaps you can be Joan of Arc? -though just a sense of humour would not have helped her.Attachment 55395

Hmmmmm. Seaworthy of Arc does have a nice ring to it LOL.

PS I have never encountered a situation where a sense of humour does not help .

[jackdale]

Originally Posted by Seaworthy Lass

Continue with your 5 step model then, but why not at least consider arcing off towards B instead of the rhumb line to instantly improve accuracy without adding any more steps?

Because that violates the principles of vectoring, which is what this is all about. I am sticking with something that has sound proven principles.

A different answer is not necessarily more accurate.

It is a been a slice - so to speak.

[HappySeagull]

It's a good idea, SWL. If there's a way to reduce some steps ( I count 7 versus 3 for RYA) it'd be an easier sell versus the "close counts! RYA method ( lodestones idea is also 7 steps)

added: rya is 4 steps I guess because destination needs marking on a long rhumb...and lodestone's becomes 8 as well.

[jackdale]

Happy

here is why mine is 5.

http://www3.telus.net/jackdale/navle...S/detercts.pps