Question for any instructor/examiner?

[Uricanejack]

So if you assume you are closer to the danger, than the cocked hat assumes you are, what do you do?
Exactly the same thing, you avoid the danger by sailing away from it.
It isn't mathematics, its common sense.
If you were blindfolded & placed near the cliff edge at Beachy Head, would it matter if you didn't know exactly how close to the edge you were?
Of course not, no-one with any sense would walk toward it, the distance, regardless of accuracy is academic, you get away from the danger until you are safe, then reassess.

Common sense is reasonable.
Someone stated it was wrong, You asked why
The why is probability?
With a simple cross, off 2 position lines, including the actual X marks spot. there are 5 equally likely spots which might be your true position.
Add another position line.
You now have 3 times as many equally likely possibilities.

 

[thinwater]

I'm guessing the exam gives three bearings and assumes they are simultanious. In fact, it took 30 seconds (or more) to take the bearings, during which time the boat moved 100 yards (30 x 10ft.s). Or at leas that is the normal reality.

 

[RJJ]

A fix contains three points of reference. Your DR gives you one point of reference. Both should be used wisely - which means, to me, that a small cocked hat is fine if it's roughly where you thought you were. If your triangle is very large, you should check for plotting errors. If it's not where you thought you were, you may find the error is you are not looking at what you think you are looking at.

In short, use all available sources of information, check them and treat the findings with healthy scepticism.

Anyway, she passed. 100pc!

 

[Babylon]

Well done your Missus!

 

[scotty123]

Common sense is reasonable.
Someone stated it was wrong, You asked why
The why is probability?
With a simple cross, off 2 position lines, including the actual X marks spot. there are 5 equally likely spots which might be your true position.
Add another position line.
You now have 3 times as many equally likely possibilities.

All that might be probability, the hazard is actuality.

 

[srm]

They presumably set the exercises so they are easy to mark

Its over 10 years since I last taught an RYA shorebased course. At that time the instructor pack included the plots printed on clear acetate sheets that could be placed over the student's chart. I always marked the chartwork assessment as soon as the student finished so we could both compare their plot with the RYA's version.

If there was any significant difference between the two I asked the student to talk me through their workings.

Other instructors will have their own methods.

 

[Skylark]

Its over 10 years since I last taught an RYA shorebased course. At that time the instructor pack included the plots printed on clear acetate sheets that could be placed over the student's chart. I always marked the chartwork assessment as soon as the student finished so we could both compare their plot with the RYA's version.

If there was any significant difference between the two I asked the student to talk me through their workings.

Other instructors will have their own methods.

It’s largely unchanged.

I'm guessing the exam.........

I always implore my students not to guess. Use references available or, if still in doubt, please ask ?

 

[[163233]]

Its over 10 years since I last taught an RYA shorebased course. At that time the instructor pack included the plots printed on clear acetate sheets that could be placed over the student's chart. I always marked the chartwork assessment as soon as the student finished so we could both compare their plot with the RYA's version.

If there was any significant difference between the two I asked the student to talk me through their workings.

Other instructors will have their own methods.

YM a mere 2 years ago and the same. As I recall there was a circle that represented the acceptable error and was quite large although that might have been the instructor's addition.

 

[MINESAPINT2]

First mate is about to do her DS theory. Her instructor has told her that any innaccuracy in plotting a fix will lead to fail. in revising ahead of tomorrow's exam, she has just obtained a 100 yard "cocked hat" and is now convinced she will fail.

I am trying to say that a 100 yard margin of error (from an object 3.5m away) is acceptable. It's a fraction of a degree, the thickness of the lines on the plotter. A big cocked hat is a prompt that you made a significant plotting error, then you check again.

More importantly in real world, if visibility is such that you can see 3.5 miles, 100 yards in open water (which you've covered several times over in the time taken between fixes) is simply neither here nor there. If you are within 100 yards of an unmarked hazard and you don't know it's there or which way lies safe water, a far-off fix isn't much good to you.

Am I right? Or is the instructor right to indicate that all 3 lines must actually cross? Trying to help 1st mate through something she is finding quite tough.

Just read this and have not read any other replies. The point I am making could have already been made clear.

Yes I would expect the LOP's to cross exactly at the same location. This is possible in laboratory controlled conditions ie. for an exam/assessment in a classroom. In my experience it would be unusual to have a top hat in an exam/assessment. There could be a number of reasons for a top hat. Incorrectly converting to degrees true, insufficient care when plotting or not understanding which part of a landmark to measure from. However as has been the case on a number of occasions previously there could be a mistake in the question.

In practice (at sea) it would be equally unusual for the intersection of a 3 point fix to meet at the same point and a cocked hat is normal.

Mike

 

[MINESAPINT2]

I’m not a shore based instructor but am a Cruising Instructor and there is no way I’d fail a DS practical student for having a 100 yard cocked hat on their 3 point fix, as long as they could demonstrate a sound approach to their workings. Most DS candidates that fail do so because there are a number of issues, not just one (with the exception of hitting another boat, running aground hard or crash gybing).

Completely agree. I am a shorebased instructor and have been a cruising instructor in the past. There is much more for an assessor to take into account in a DS course than a slight error in a 3 point fix. The instructor is the only person in a position to make a proper assessment in this case and I am sure they will do so. There are always one or two people in a class who struggle. People who have not done the DS or YM shorebased course should do so and will then realise neither are a walk in the park. Nor are they an attendance course, you do not get your certificate for just turning up.

Mike

 

[Iliade]

I have never seen the exam, But is this the issue being found/considered? (fix points kept jumping to a grid so not perfectly aligned)

 

[jordanbasset]

When I did my theory it was made very clear that in real world conditions you would expect a cocked hat and gave the reasons for that. But they also said in conditions in the classroom there was no reason you should not have an exact fix or pretty much an exact fix, which to be fair the large majority of us achieved

 

[Wansworth]

Isn't the point of a three-point fix to help identify errors in sights or mistakes in plotting?

Expecting three lines to cross exactly is asking the impossible.

Especially on a dark night in a gale and swishing spring tide!

 

[Cotillion]

I’ve never known anyone to fail these RYA courses and I’ve been out with some exceptionally stupid people (one in particular springs to mind). The certificate is for completing the course. Exams may be a different matter but I can’t comment on them as I’ve never done one.

 

[[163233]]

I’ve never known anyone to fail these RYA courses and I’ve been out with some exceptionally stupid people (one in particular springs to mind). The certificate is for completing the course. Exams may be a different matter but I can’t comment on them as I’ve never done one.

The theory courses end with an exam that you have to pass to get the certificate.

 

[srm]

I’ve never known anyone to fail these RYA courses and I’ve been out with some exceptionally stupid people (one in particular springs to mind). The certificate is for completing the course. Exams may be a different matter but I can’t comment on them as I’ve never done one.

Really? Exactly what do you base this assertion on? especially as you admit to having no experience of the 'exams'.

There are assessment papers (or exams) at the end of the shore based courses. However, the full certificate is only issued after a practical course and practical assessment. As to your "exceptionally stupid people", many in the sailing community may say they have been sailing for many years, but actual sea time could be a matter of a week or two a year of which much of that time will be at anchor or in harbour.

I am an ex-YM instructor who also ran shorebased courses for over 20 years as winter evening classes. My experience with shorebased courses was that people who may not pass tended to drop out before the end of course assessments (or exams if you prefer). Of those who took the assessment papers some did not make the grade at first attempt. These people were offered re-sits after further instruction.

 

[Elessar]

In fact, if the 3 lines do cross exactly, there is more chance that they are wrong than right..

I think I once read somewhere that, despite most of us putting a dot in the middle of the cocked hat, in order to mark our position, there is a strong chance that the actual position is outside the cocked hat. It was a long time ago, so I cant recall how it was justified, but I recall it being a well made point.

nearly right.

Actually the actual position is probably outside the cocked hat.
I suppose "strong chance" could be argued to mean "probably", but "probably is less ambiguous.

 

[john_morris_uk]

Only two days ago I wrote the report up on someone I'd had to fail the exam they'd taken a couple of weeks ago.

Just to put the record straight, people certainly DO fail RYA courses and exams.

 

[Elessar]

The RYA courses, have always taught that your assumed position if a cocked hat, is nearest to the hazard, it isn't a novel concept.
PS, the RYA handbook, if read properly, explains everything, no additional books are needed, however some people think their 'cartoon' format is somehow beneath them.

If I was teaching you I would NEVER use that concept which I believe is flawed.
It allows people to think that the edge of the hat is the limit of the position they could be in. This is incorrect. The larger the hat the more scepticism you should give to the assumed position, but that is the only thing the hat size tells you.

 

[alexincornwall]

I’ve never known anyone to fail these RYA courses and I’ve been out with some exceptionally stupid people (one in particular springs to mind). The certificate is for completing the course. Exams may be a different matter but I can’t comment on them as I’ve never done one.

DS candidates definitely have and will fail (either theory or practical).

The theory isn't actually obligatory but it's a very good idea for people that don't have many sea miles behind them. In my opinion the leap from nothing to DS level is trickier going from DS to Yachtmaster theory. If I get a DS on their practical exam and they've not done their theory week then that's going to be the area that I'd be focussing on. They are usually experienced sailors who often come unstuck on the theory. If they've done their theory recently I'd probably be eying up their boat handling skills in more detail because somebody else has already spent a week assessing their chart work.

Regardless, I'd say between 2 and 4 in every 10 would fail. Interestingly I never seem to come across particularly rounded DS candidates, which is quite different to those going for their Yachtmaster. Those with good boat handling and seamanship skills are quite often a little ropey on theory. Those that are very strong on the theory side have a habit of making strange decisions where practical tasks are concerned.

I've never failed a competent crew candidate though...