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Old 20-10-2018, 14:20   #1
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course test

Hi

In preparation of getting our boat we are going through some online learning. The Navigation part has 30 questions, all of which have to be answered correctly. The problem is we keep getting 29 right and it won't indicate which we have got wrong. The attached shows the three I am least confident about so wonder if anyone can guide me. I have tried to find an online source for the chart symbols but am struggling so only have my handbook to go on. Help would be appreciated

cheers
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Old 20-10-2018, 14:41   #2
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Re: course test

looks like I am having trouble with the attachment. I have it as PDF and doc
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Old 20-10-2018, 15:27   #3
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Re: course test

Hi, Elaine and Tony,

Try this link for adding attachments: How to: Add images to a Post.

Ann
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Old 20-10-2018, 16:25   #4
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Re: course test

I notice your from Kiwi Land. Used to be on the LINZ web site as NZ201 but the buggers have dropped it. Replaced with a link to UK Admiralty Chart Symbols but link doesn't work. I searched and can't find it.
But here's a link to the US equivalent. NOAA Chart No 1
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Old 20-10-2018, 18:41   #5
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Re: course test

I will try to explain one I am struggling with. It is around variation. There is an image of the compass with the arrow just off to the east from 0 degrees and has the following words on the bearing. 19(degrees) 20' E 2012(1'E)

The question is "on a chart these numbers on the compass rose indicate?

1) Magnetic variation - East nearly 20 degrees
2) Magnetic.....West
3) Magnetic.....South
4) Magnetic..... North

I have answered east because it is to the East of 0 degrees but can;t really understand the terminology.
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Old 20-10-2018, 19:40   #6
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Re: course test

Variation is the difference between True and Magnetic heading/bearing. In the example given, the variation in 2012 was 19 degrees, 20 minutes, with and annual increase of 1 minute per year - so in 2018, it would be 19 degrees, 26 minutes East.
The "East" part means that magnetic North lies East of True north - the reason the compass rose is offset that amount on the chart. To convert a True course that you measure on the chart to magnetic (so you can steer it), you would subtract the Variation from the True course. Example: you measure a True course of 90 degrees on the chart (due East along a line of latitude) - to steer that course, you would steer 70 degrees and 34 minutes (but nobody can steer that close .
Variation is either West or East, and varies widely around the world, since the magnetic pole is quite a ways from the True pole nowadays (and it is in motion).


Best of luck with your lessons!


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Old 20-10-2018, 19:49   #7
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Re: course test

Quote:
Originally Posted by Elaine and Tony View Post
I will try to explain one I am struggling with. It is around variation. There is an image of the compass with the arrow just off to the east from 0 degrees and has the following words on the bearing. 19(degrees) 20' E 2012(1'E)

The question is "on a chart these numbers on the compass rose indicate?

1) Magnetic variation - East nearly 20 degrees
2) Magnetic.....West
3) Magnetic.....South
4) Magnetic..... North

I have answered east because it is to the East of 0 degrees but can;t really understand the terminology.

Is that the actual wording in the test? If so, the test developer needs a good slap.
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Old 20-10-2018, 19:54   #8
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Re: course test

OK, now I'm confused. Luckily for me, where we live there is practically no compass variation. Still... If magnetic north is almost 20 degrees east of true north, then to steer a course of 90 deg true, wouldn't that be 110 deg magnetic?
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Old 20-10-2018, 20:35   #9
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Re: course test

^^ Yes.
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Old 20-10-2018, 20:37   #10
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Re: course test

Quote:
Originally Posted by Hartleyg View Post
Variation is the difference between True and Magnetic heading/bearing. In the example given, the variation in 2012 was 19 degrees, 20 minutes, with and annual increase of 1 minute per year - so in 2018, it would be 19 degrees, 26 minutes East.
The "East" part means that magnetic North lies East of True north - the reason the compass rose is offset that amount on the chart. To convert a True course that you measure on the chart to magnetic (so you can steer it), you would subtract the Variation from the True course. Example: you measure a True course of 90 degrees on the chart (due East along a line of latitude) - to steer that course, you would steer 70 degrees and 34 minutes (but nobody can steer that close .
Variation is either West or East, and varies widely around the world, since the magnetic pole is quite a ways from the True pole nowadays (and it is in motion).


Best of luck with your lessons!


Hartley
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No. Post #8 has it correct.
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Old 20-10-2018, 20:44   #11
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Re: course test

When I teach this we use:

(create your own) TVMDC (add whiskey) to go from True to Compass (for steering) and
Can Dead Men Vote Twice (at Elections) to go from steering compass to the chart plot. Good luck in your studies!
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Old 23-10-2018, 23:35   #12
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Re: course test

Quote:
Originally Posted by Wotname View Post
No. Post #8 has it correct.
Err, wot?

Scott has given the traditional method; I find a simple way to avoid errors is to write the letters vertically, and fill in the values as I have them. So, in this thread's example I would start like so:

T → 090°
V → 20° E
M →
D →
C →

The traditional mnemonic for TVMDC ends in "; add whiskey", meaning that as you go down that line you add westward variations and deviations and subtract the eastward ones. Thus, the result is shown as:

T → 090°
V → 20° E
M → 070°
D →
C →

As a confirmation, you can refer to the compass rose on a chart. I've tried to attach one from the SF Bay Area, showing a variation of 14°E; you can see that 90° on the outer True ring corresponds to about 76° on the inner magnetic ring.
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Old 24-10-2018, 00:10   #13
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Re: course test

Regardless of the application, seems the OP is answering the question posted correctly ("19(degrees) 20' E" does indeed indicate "East nearly 20 degrees"). So, what are the other two questions of which you are suspect?
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Old 24-10-2018, 11:36   #14
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Re: course test

I’ve always used
“True Virgins Make Dull Company”
East is Least
West is Best

or less racey
“T V Makes Dull Children”

Cheers
Neil
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Old 24-10-2018, 18:43   #15
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Re: course test

Quote:
Originally Posted by requiem View Post
Err, wot?

Scott has given the traditional method; I find a simple way to avoid errors is to write the letters vertically, and fill in the values as I have them. So, in this thread's example I would start like so:

T → 090°
V → 20° E
M →
D →
C →

The traditional mnemonic for TVMDC ends in "; add whiskey", meaning that as you go down that line you add westward variations and deviations and subtract the eastward ones. Thus, the result is shown as:

T → 090°
V → 20° E
M → 070°
D →
C →

As a confirmation, you can refer to the compass rose on a chart. I've tried to attach one from the SF Bay Area, showing a variation of 14°E; you can see that 90° on the outer True ring corresponds to about 76° on the inner magnetic ring.
Err... Wot is wrong
Thanks for the timely correction Requiem and for posting the correct information.

My apologies for getting it totally about face - mea culpa

My lifetime membership to the navigator guild is under review...

So how did it happen, this is stuff I have always known intuitively, never had to remember anything or use some technique and have been doing it almost forever. On reflection, I did fail to mentally confirm my response before posting and I also failed to provide a logical explanation of my response. Had I did so, I would have realised the error before hitting the reply button.

Thanks again for posting the correct information and causing me to reflect on how my error came about.
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