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Learning the HARD way...
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Discussion Starter · #1 · (Edited)
I have been working on the ASA Instructor packet. I passed the ASA exam several years ago, and was looking forward to teaching this stuff...

For my OUPV I received 100% on the navigation skills assessment. However, the ASA Coastal Navigation Review question number 6 has me stumped.

You can find the entire ASA Coastal Navigation Examination Review Questions & Answers here

Based on Chart 1210 TR, Year 1985
Here is the relevant section of the chart;


5) Plot a course from the W Or "A" (41° 16.6'N, 071° 24'W.) to Whale Rock buoy (41° 26.7'N, 071° 25.2'W)
a) What is the course?

Magnetic: 010º m

Compass: 015º psc

From a DR position abeam of R"2" (41° 20'N, 71° 28.6'W), plot a danger bearing to avoid the wreck east of your course line (wreck is east of buoy W Or "E"). Use Brenton Reef Light for your bearing.

b) The danger bearing is: Magnetic: 017º m

c) Brenton Reef Light should bear NO MORE/NO LESS (delete one) than the danger bearing to remain safe. NO LESS - The bearing should INCREASE as you pass the wreck.
Eazy peazy... My answers above (in RED) are within 1º of the answers on the review. But now things go astray

6) At 1600, on the same course established in question 5, the Point Judith Light (GP Occ (1+2)) bears 300°M. At 1620, the same light bears 270°M. Both bearings are taken with a hand-bearing compass (assume no deviation). Plot a running fix for 1620. Boat Speed is 4 knots.
Let me plot this;


20 min at 4 knots = 1.333 knots

a) What is your Running fix position? Lat: 41º 22.5' N Long: 71º 24.65' W
The lattitude answer is OK (answer sheet says 41º 22.35') but the longitude is wrong. 71º 25.7'
b) What is the Course Made Good/Track from the W Or "A"buoy? Magnetic:
without a valid fix, I cannot compute this, or any of the following.
Assume the difference between the Course Made Good and the heading to be due to leeway (no
current).
c) What is the leeway?

Considering leeway, plot a new course to the Whale Rock buoy.

d) What is the course? True:

e) What is the heading? Magnetic:

Compass:
I know that a bunch of you have been down this road, and believe that I cannot be the only one to be stumped by this. :confused::confused:

Am I missing something obvious? Careless error somewhere?

Also, because I have found all of this stuff posted elsewhere online, I don't believe that I am giving anything away. I think that it may also help others that follow in my wake...
 

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I'm at work now so I don't have my book and notes, so I can't remember if this was one of them, but....

There are a couple typos in the book we used. I took 105 a year ago and if I'm remembering correctly there were two instances where things didn't/couldn't work out.
 

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I have not tried to plot this but
No deviation still mean that you must take magnetic variation into account.
Also the yearly changes..
I can see that you plotted m, I would have converted to t(rue) before plotting.
In your case
Compass = Magnetic (since no deviation)
Magnetic != true (Because magnetic variation)

And if the distance between the two positions is different from your DR position you must move your track parallel to the plotted course so your triangulation is correct.

I would be skeptic if your observed position after these two bearings is the same as your plotted (DR) position.

Sorry if I'm using different words than you are used to, I learnt to navigate in Norwegian..
 

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Assume the difference between the Course Made Good and the heading to be due to leeway (no
current).
c) What is the leeway?

Considering leeway, plot a new course to the Whale Rock buoy.

d) What is the course? True:

e) What is the heading? Magnetic:
The follow up questions indicate that I'm on the correct track
Your plot is nor complete, you should most probably have found that you have leeway after plotting those two bearings.
 

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Learning the HARD way...
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Discussion Starter · #5 ·
I have not tried to plot this but
No deviation still mean that you must take magnetic variation into account.
Also the yearly changes..
I can see that you plotted m, I would have converted to t(rue) before plotting.
In your case
Compass = Magnetic (since no deviation)
Magnetic != true (Because magnetic variation)

And if the distance between the two positions is different from your calculated position you must move your track parallel to the plotted course so your triangulation is correct.

I would be skeptic if your observed position after these two bearings is the same as your plotted (DR) position.

Sorry if I'm using different words than you are used to, I learnt to navigate in Norwegian..
Thanks for the reply, but this is an academic exercise. Deviation is not requested for this question, and therefore not relevant, because it is an exercise.

Variation is already factored in to the chart (look at the compass rose). I believe that we can safely assume, because it is an exercise, that the navigator is preforming these calculations in 1985.

I think that the central issue is that I have plotted a course, and am asked to plot a running fix at 1600 and again at 1620. I don't know when I left the starting location, and I don't have a second bearing to compute a fix...

wait a min...

Because I KNOW the intended course, I could assume that I am traveling parallel (or almost parallel) to that course. I KNOW the distance that I should have traveled over 20 min = 1.333 nautical miles. I suppose that I could find a place on the running fix that corresponds to 1.3 nautical miles.

Your use of english, and navigation terms are very good.
 

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Thanks for the reply, but this is an academic exercise. Deviation is not requested for this question, and therefore not relevant, because it is an exercise.

Variation is already factored in to the chart (look at the compass rose). I believe that we can safely assume, because it is an exercise, that the navigator is preforming these calculations in 1985.

I think that the central issue is that I have plotted a course, and am asked to plot a running fix at 1600 and again at 1620. I don't know when I left the starting location, and I don't have a second bearing to compute a fix...

wait a min...

Because I KNOW the intended course, I could assume that I am traveling parallel (or almost parallel) to that course. I KNOW the distance that I should have traveled over 20 min = 1.333 nautical miles. I suppose that I could find a place on the running fix that corresponds to 1.3 nautical miles.

Your use of english, and navigation terms are very good.
I could not read the yearly change on your uploaded picture, nor did I try to plot. I was trying to analyse it from the start..

You have to find a line parallel to the plotted course where the distance between the two bearing lines is 1.333 nm
Next step is to calculate leeway, and answer the remaining questions:)
 

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Learning the HARD way...
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Discussion Starter · #7 · (Edited)
I could not read the yearly change on your uploaded picture, nor did I try to plot. I was trying to analyse it from the start..

You have to find a line parallel to the plotted course where the distance between the two bearing lines is 1.333 nm
Next step is to calculate leeway, and answer the remaining questions:)
BINGO!!
:thewave:

This is what I surmised in Post #5... I had done this years ago, but appear to have forgotten.

Running Fix is now Lat: 41º 22.8'N Long: 71º 25.9'W
Close to the answer sheet's; 41º 22.35'N 71º 25.7'W

Course made good by my calculations is now 000ºm - answer sheet says 003ºm

This seems REALLY imprecise because I have no idea if the current or wind are helping or hurting my fix....
 

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Discussion Starter · #8 · (Edited)
Looking closer, I changed CMG to 001ºm - close enuf to 003º
Here is the revised chart;


For leeway, I calculated 009º
 

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Just a little comment on your approach to solving the exercise.

If you are going to teach navigation to students I think it is good practice to do stuff the proper way.
Always plot courses and bearings using true direction.
Always use variation and yearly change in calculations.

It's better to learn a method that works everywhere & every time instead of methods that work sometimes..

If you combine modern plotters with traditional navigation it is important to operate with one type of directions, the plotter will happily give you true bearing and COG.
 

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Looking closer, I changed CMG to 001ºm - close enuf to 003º
Here is the revised chart;


For leeway, I calculated 009º
That is not how to calculate a running fix. You advance the first bearing (LOP) by the distance traveled.

60 D = ST
D= ST/60
D= 4*20/60
D=1.333 miles

Advance the 1600 bearing by 1.3 miles. Where that Advanced LOP intersects the 1620 LOP is the RFix.

These are my notes on doing a running fix

http://www3.telus.net/jackdale/navlessons/Running.pdf
 
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I used the Tools in OpenCPN and Elements to show my plotting. That special purpose buoy is not shown in this chart, so I used its lat and long



Be careful with labelling as well. In Sail Canada (CYA) plotting and labeling is worth marks. Is that also true in ASA?

I have just done a cross over from Sail Canada to ASA. I have to do 214 (catamaran) separately, so I am going to Sausalito next week. So I am also studying. Any advise would be gratefully accepted.
 

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Discussion Starter · #13 ·
Thanks jackdale!

While very similar to what I did, it was not the same. I forget this stuff!:eek:

Based on your notes, here is my solution to the problem;
Step 0: Plot the intended course & danger bearing;
Step 1: Establish LOP on known object;

Step 2; Maintain course and heading for specific time, and establish second LOP on the same object;

Step 3; Advance LOP from first bearing by the distance traveled using 60 * D = S T;

Step 4: Running Fix is where the two lines cross. Plot Course Made Good (CMG);
 

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Next steps:

- plot original DR position anticipated at 1620
- compare 1620 running fix to 1620 DR and calculate set and drift
- apply set and drift to DR course out of 1620 running fix or, better still, recommend course change out of 1620 running fix to compensate for set/drift and still avoid being run up on the lee shore of Pt Judith Neck.
 

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Thanks jackdale!

While very similar to what I did, it was not the same. I forget this stuff!:eek:
Your plotting looks good. Check the labeling. I forgot to to label the course line. It should also have one arrow on it.

C 354_____>_________
S 4.0

The CMG line should have two arrows.
 

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Next steps:

- plot original DR position anticipated at 1620
- compare 1620 running fix to 1620 DR and calculate set and drift
- apply set and drift to DR course out of 1620 running fix or, better still, recommend course change out of 1620 running fix to compensate for set/drift and still avoid being run up on the lee shore of Pt Judith Neck.
You need a departure time from the buoy to get a DR.
 

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Discussion Starter · #17 ·
Your plotting looks good. Check the labeling. I forgot to to label the course line. It should also have one arrow on it.

C 354_____>_________
S 4.0

The CMG line should have two arrows.
Like this?

 

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Like this?
Exactly.

I was also taught to put hash marks in a danger bearing line and label as either NLT or NMT

_______NLT 090__________________________!
//////////////////////////////////
+ + + +
 

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The course line should have the course in true on top and the speed (from the knotmeter) on the bottom.

 

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Discussion Starter · #20 ·
I used the Tools in OpenCPN and Elements to show my plotting. That special purpose buoy is not shown in this chart, so I used its lat and long
I pulled up a copy of the 1210tr chart from Ocean Graphics;http://www.oceangrafix.com/chart/zoom?chart=1210TR .

Be careful with labelling as well. In Sail Canada (CYA) plotting and labeling is worth marks. Is that also true in ASA?
Not sure.... IIRC, ASA only looked at the fill_in_the_dots answer sheet.

I have just done a cross over from Sail Canada to ASA. I have to do 214 (catamaran) separately, so I am going to Sausalito next week. So I am also studying. Any advise would be gratefully accepted.
I'd love to help, but I'm having enough trouble with one hull:). Good luck on the test!
 
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