Question for any instructor/examiner?

MINESAPINT2 said:
.....In my experience it would be unusual to have a top hat in an exam/assessment....

.....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
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Where does the expression "top hat" come from. Is it from a four-point fix?
 
As a sailing instructor I don't recall failing anyone. Of course I wasn't an RYA instructor.
Perhaps its a limitation of being both the instructor and the examiner. Its also due to my particular subjectivity. Personal opinions ect.
Even as an examiner, I viewed the exam as a learning and teaching opportunity.
When I found a candidate lacked knowledge, I would go over the point again, explain it so it was understood. If the candidate could then demonstrate what was required I was happy.
Why, my personal belief anyone smart enough to take a course for recreational sailing was well on the way to a pass already. I did my best to help them learn.

To my knowledge passing or failing the theory course doesn't get you a certificate.
Would I be so lenient if examining for the RYA? probably not. I would have to consider the possibility the candidate might want to use the RYA certificate commercially.
Even so, the primary reasons for an exam at the end of a course is to ensure the candidate has understood the content. The exam is just a tool to see if they have.
Particularly at a basic entry level, Just go over the question, figure out why they got it wrong, Then explain how it should have been done. Then get the candidate to demonstrate how to do it correctly.

Pull out my rubber stamp, Pass.
If on the other hand someone still doesn't understand your not doing them any favour giving them a false impression.
 
Uricanejack said:
To my knowledge passing or failing the theory course doesn't get you a certificate.
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Ta da! (Not mine, google is amaaaaazing..)

IMG_2675-1-e1463552757324.jpg


It's actually required if you want the DS commercially endorsed.
 
Elessar said:
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.
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But in the absence of any other information (e.g. depth adjusted for height of tide) the assumption that you're at least somewhere in the region of the cocked-hat nearest the hazard is a better starting point than nothing.
 
Babylon said:
But in the absence of any other information (e.g. depth adjusted for height of tide) the assumption that you're at least somewhere in the region of the cocked-hat nearest the hazard is a better starting point than nothing.
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That’s fair. Because you understand the cocked hat.
But teach it that way and there is a real risk assume they are in the cocked hat.
That’s the problem.
 
Really you should factor in the probable error for each bearing, maybe 5 degrees either way, and draw the largest hat possible, maybe a sombrero.
 
Sharky34 said:
They are in the cocked hat, within the triangle, but in the triangle bit closest to the hazard.
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How do you know this?
As I said they are probably not in the cocked hat.
If you are assuming they are in it with no other information you are ably demonstrating why the corner of the hat theory is a potentially dangerous one.
 
Elessar said:
How do you know this?
As I said they are probably not in the cocked hat.
If you are assuming they are in it with no other information you are ably demonstrating why the corner of the hat theory is a potentially dangerous one.
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How so?
There are 3 bearings, plotted onto a chart after correction to true, so why are they not in a cocked hat?
 
Sharky34 said:
How so?
There are 3 bearings, plotted onto a chart after correction to true, so why are they not in a cocked hat?
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Exactly

Lack of understanding makes the triangle cocked hat theory dangerous.

To answer your question.

Your first bearing. Almost impossible to get it “right”. There is a 50% chance your error is to the left, 50% your error is to the right.

Your second bearing. 50:50.

Your 3rd bearing and you have a hat. Now for that bearing you have a 50% chance of being inside the hat and 50 % of being outside the hat.

Take the errors on the first two bearings and convert left : right to in : out and there is only a small chance you are inside the hat. You are probably outside that hat.

Your assumptions are potentially dangerous.
 
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Elessar said:
Exactly

Lack of understanding makes the triangle cocked hat theory dangerous.

To answer your question.

Your first bearing. Almost impossible to get it “right”. There is a 50% chance your error is to the left, 50% your error is to the right.

Your second bearing. 50:50.

Your 3rd bearing and you have a hat. Now you are 50% inside the hat and 50 % outside the hat.

Take the errors on the first two bearings and convert left : right to in : out and there is only a small chance you are inside the hat. You are probably outside that hat.

Your assumptions are potentially dangerous.
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Well, I've used that method for more years than I wish to remember, so cannot agree with your theory.
Fail to understand, why 1st bearing should be "almost impossible to get correct", why?
 
Sharky34 said:
Well, I've used that method for more years than I wish to remember, so cannot agree with your theory.
Fail to understand, why 1st bearing should be "almost impossible to get correct", why?
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Good for you. I hope your luck holds out.
If I were you I’d make sure I had a decent plotter so you don’t have to rely on your fixes.
(Clue:every bearing is almost impossible to get correct)
 
Elessar said:
Good for you. I hope your luck holds out.
If I were you I’d make sure I had a decent plotter so you don’t have to rely on your fixes.
(Clue:every bearing is almost impossible to get correct)
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Why, is every bearing almost imposs8ble to get correct?
You keep repeating, with no explaination.
 
Sharky34 said:
Why, is every bearing almost imposs8ble to get correct?
You keep repeating, with no explaination.
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I didn’t think it necessary to state the obvious.
Boats move and hand bearing compass gradations are quite course are the major 2 factors.

The simple fact is that if your bearings are accurate, there will be no cocked hat, your lines will perfectly intersect. Great. Move on

If there is a cocked hat, one or more of your bearings are not perfect.
It is not possible to know if the error is plus or minus which is why you are probably outside the cocked hat.
 
Sharky34 said:
Why, is every bearing almost imposs8ble to get correct?
You keep repeating, with no explaination.
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No explanation required, for anyone who has ever actually used a handbearing compass on a boat afloat.
No substitute for getting out there and giving it a go.
Start by taking a few bearings when you know exactly where you are, on land or flat water.

Back in the days before GPS, people were more used to the concept of not knowing exactly where they were, or needing to.
And when you did need to know accurately, you had a plan in place to keep you the right side of things.

You soon realised the value of transits over compass readings.
 
Following on from that, I remember an Open University video from yonks back saying in effect:

You have a 50% chance of being either side of the line you have drawn. You draw 3 lines. The probability of being in the 'cocked hat' is therefore 50% of 50% of 50% = 12.5% or 1 in 8!
 
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Joker said:
Following on from that, I remember an Open University video from yonks back saying in effect:

You have a 50% chance of being either side of the line you have drawn. You draw 3 lines. The probability of being in the 'cocked hat' is therefore 50% of 50% of 50% = 12.5% or 1 in 8!
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Yes. As I have said all along. You are probably outside the hat.
 
Elessar said:
Yes. As I have said all along. You are probably outside the hat.
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Or according to you, a 50% chance of being within it.
May as well not bother if in your theory it is so imprecise.
Mariners have obviously been wrong all these years, amazing we have any charts drawn from bearings.
 
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