Inaccurate RYA Teaching : CTS - Quest For a New Method

[HappySeagull]

Originally Posted by Seaworthy Lass

Happy, your artistry is remarkable, but I need a little help interpreting this example. I see an arrival point in the centre of the diagram (or is that the departure point?). I can't see any vectors lined up in the same direction indicating boat displacement following a single CTS. Are the green lines the current?
I know true art should not be dissected, but please lend a wing here.

PS Thankfully your gonads were not at stake. Castrated seagulls (not that I am into violence, but other CF members do seem to have a tendency towards this) are no longer very happy ones

OK! I try again to make this example plain Here is the "hard case" better shown....when I looked at it again I couldn't make sense out of it either! but this should be better. Between this and the second example, you can see where I'm at with this. It really uses RYA for each drift hour, and then finds proportion.



and these are the vectors that prove I arrive...red dot line is vectors CTS + Current drift.


added and solid red is the "estimated", "real "track.

[Seaworthy Lass]

Originally Posted by jackdale

I may see advantage if you can post a real world example that shows a sigificant difference. The criteria are:

• A real passage
• Real current data based in current tables, current diamonds, electronic data, etc..
• A boat that will make decent speeds ,e.g., 5 knots is my usual planning speed.

I will certainly do this come spring/summer when winter chores on board are not all time consuming. Evenings are time for relaxing at the moment, not downloading new programs. I only have an old version of OpenCPN on an old laptop buried somewhere (unused since iPads were purchased).

The only thing I don't understand is your limitation of "decent speed" in any examples I give. Does the RYA technique only work if you are averaging 5 knots or more? A CTS method should work with any speed data you choose to input.

So, give me some time and I will find some real data. Some of the passages I have made in northern Queensland in Australia would demonstrate my points well

Jackdale, I would have dropped all this weeks ago had it just been an issue affecting only me (I would have just used my technique rather than the RYA's and not pushed my point). I am only persisting as this is a method widely and internationally taught and although it may apply well in lots of situations, it does fail frequently as well.

The RYA technique can be improved with not much more effort involved (even just simply arcing off towards B instead of the rhumb line would improve the method) yet for some reason I am meeting with huge resistance. I truly don't understand it. Over the last centuries/millenia we would never have advanced had "tried and true" methods not been challenged and improved. I truly don't see that challenging one aspect the the RYA's teaching makes me some kind of awful vindictive shrill person as I have been labelled .

[jackdale]

Originally Posted by goboatingnow

Why keep interjecting SWL, what are you seeking to do, Take it up with the RYA, even better have a go on YBW.com , on its forums, loads of RYA instructors there to take pot shots at.


Dave

You might start with this discussion.

Calculating a route across multiple tides

In particular check out post #14. You might recognize the authors name.

[HappySeagull]

don't know what the rainbow mark is upper left! or what it means! ignore it.

[DeepFrz]

Wow, I stopped reading at post 659 and here we are at 815. I'm just beginning to see why parliament doesn't work.

[Seaworthy Lass]

Originally Posted by jackdale

In the RYA method, you are crabbing down the rhumb line.

Not usually! The only time you are close to doing this is if the tidal stream does not change much from hour to hour and the journey is short, as in this example you have given (it only increases 0.22 knots after the first hour, almost a constant current flow).

Originally Posted by jackdale

Jackdale, you have selected the wrong data for current in this example.
It is:
1.63 knots AT 9:00 so this would be roughly the average current from 8:30-9:30, not from 9:00 to 10:00 as you have shown.

The same applies for the second hour too:
1.85 knots at 10:00 means this is roughly the average current from 9:30-10:30

Also if the expected arrival time is 11.14 using the RYA method, why does this not coincide with the destination on your diagram?

[HappySeagull]

Originally Posted by DeepFrz

Wow, I stopped reading at post 659 and here we are at 815. I'm just beginning to see why parliament doesn't work.

Funny!
maybe Call Guiness book of Records!

[goboatingnow]

Originally Posted by jackdale

You might start with this discussion.

Calculating a route across multiple tides

In particular check out post #14. You might recognize the authors name.

I have had the honour of meeting the man once. However Mr Cunliffe remains my hero

Dave

[Seaworthy Lass]

Originally Posted by jackdale

You might start with this discussion.

Calculating a route across multiple tides

In particular check out post #14. You might recognize the authors name.

I will read all 5 pages of the posts on this YBW thread after dinner. The discussion is over three years old now, it is not current, but it will still be interesting.

I note that post #14 on the YBW thread was made by Tim Bartlett, the author of the RYA Navigation Handbook. He is no longer a YBW forum member, his old posts there now appear labelled "guest". Does anyone know why he is no longer a member? I heard he was banned from YBW.

I would have welcomed a discussion with him on this topic. I emailed both the RYA and Tim several weeks ago regarding the points I have raised here, but other than the automated standard response "we have received your email", I have heard nothing in reply .

I am astounded that so many issues are discussed and sometimes heatedly debated on CF on such a wide variety of nautical subjects, but when it comes to the important subject of navigation, when I raise a discussion regarding improvements that could be made in the RYA teaching, I am told by GoBoatingNow (an RYA instructor) that I should leave the forum and take the discussion elsewhere.

I bet over the decades lots of people have recognised the problems with the RYA technique but have just been bullied into submission when they have tried to comment on improvements that could be made.

This lassie does not respond well to bullying.

[goboatingnow]

The RYA technique can be improved with not much more effort involved (even just simply arcing off towards B instead of the rhumb line would improve the method) yet for some reason I am meeting with huge resistance. I truly don't understand it. Over the last centuries/millenia we would never have advanced had "tried and true" methods not been challenged and improved. I truly don't see that challenging one aspect the the RYA's teaching makes me some kind of awful vindictive shrill person as I have been labelled

You have advanced no proof that your method is "improved", Only by comparison with real life can you state that. You cant use your assumptions to prove your assumptions.

The " RYA teaching" of course is nothing of the sort. The RYA does not care in a YM exam on your boat what method you use to get a CTS, as long as you can demonstrate that you know what you are doing.

Lastly all these methods have a fundemental inaccuracy in that they are based on a single point of data at a single point in time in a particular geographical position. Unless you can show that your method actually delivers real and quantifiable advantages in real life that provide a "safer" CTS, then little has been achieved

The "RYA method" like all methods, just like yours, has in built assumptions, those assumptions will have an inherent error associated with them.

There is no huge resistance, You havent discovered any new, anyone looking at single CTS will point out any number of theoretical inaccuracies.

What there is resistance to is the claim that its any "better" in real life , with real boats and real tides. No proof has been advanced to that effect

dave

[Seaworthy Lass]

Originally Posted by DeepFrz

Wow, I stopped reading at post 659 and here we are at 815. I'm just beginning to see why parliament doesn't work.

LOL!
Stamina has certainly been needed, but at least we have advanced to the point that I am no longer being called confused and ignorant and my method fatally flawed . Progress is being made

[goboatingnow]

I am told by GoBoatingNow (an RYA instructor) that I should leave the forum and take the discussion elsewhere.

I am all in favour of the CF discussion on an examination of various CTS theories. I specifically referred to your constant attack on the RYA method as if you have something personal against the RYA, I suggested you take that discussion to YBW as there are more RYA types to take pot shots at.

please please stop constantly misrepresenting my position and the RYAs, debate the issues of the data, the real application of the methodologies etc. Just stop constantly going on about the RYA, Theres hardly one post that you dont mention it in .

Dave

[HappySeagull]

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

The plots should say it all and their merits can be argued.

[Seaworthy Lass]

Originally Posted by goboatingnow

I am all in favour of the CF discussion on an examination of various CTS theories. I specifically referred to your constant attack on the RYA method as if you have something personal against the RYA, I suggested you take that discussion to YBW as there are more RYA types to take pot shots at.

please please stop constantly misrepresenting my position and the RYAs, debate the issues of the data, the real application of the methodologies etc. Just stop constantly going on about the RYA, Theres hardly one post that you dont mention it in .

Dave

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.

[goboatingnow]

I agree HS, there is a serious issue here and one that is useful to consider

Given the very approximate nature of tidal data, what is to be gained by increasing precise theoretical methods.

(a) Does anyone really sail this way , ie into the harbour mouth on a single CTS computed hours ago from often sparse tide data

(b) Is it actually safe to widely depart from the rhumb line, what about wind shifts etc

(c) why would anyone leave on a say 10 hour trip and rely on a computed tide 10 hours ahead to actually allow us to make port


what are the real life errors and therefore what is the "advantage "of applying one method over the other.

These are useful things and it was where this thread ( well two threads ago) started. It then degenerated into a RYA bashing session.

Dave