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#### davidpm

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I would draw a line through the lookout tower and Cuttyhunk Island
Then I would put a dot anywhere on the line preferably in open water.
Then through that dot pointing somewhere west of north I would draw a line through the dot so that the angle between my northwest line and my south east line was 130 degrees.
Then I would use a parallel rule to find out the magnetic heading of this second line.
The difference between the magnetic heading of the second line and 300 is your deviation.

There are real navigators on this forum but maybe this will get you started.

This is how I thought about it.

If you see the lookout tower and the Island in line then you have to be somewhere on a line that connects those two.
The only question is where on the line and which direction you are pointing.
We don't know nor care where on the line but we know we are pointing 130 degrees west of the line because that is what the Pelorus says.

Now we can tell what our magnetic heading should be.
If it doesn't match our compass the difference must be the deviation.

It looks like the second question is the same as the first just different numbers.

I'm just guessing here but does this make sense?

MrA

#### davidpm

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just Saturday morning I drove an hour to see the teacher, he's not teacher material too long in the Marines, he believes every new sailor should be as smart as he, well he solved the problems right in front of me and still I can't get back to his numbers T=299, V=015W, M =314, D=003W, C=317 and the other problem T=290, V 015W, M=305, D=005E, C=300, thanks
Please expand on what the letters mean.
What is D C etc.

Oh I just remembered True, Varitation, Magnetic, devation, compass

Also please quote the problem exactly, word for word with nothing added or left out including exact punctuation.

MrA

#### davidpm

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just Saturday morning I drove an hour to see the teacher, he's not teacher material too long in the Marines, he believes every new sailor should be as smart as he, well he solved the problems right in front of me and still I can't get back to his numbers T=299, V=015W, M =314, D=003W, C=317 and the other problem T=290, V 015W, M=305, D=005E, C=300, thanks
I suspect their is a missing piece of the puzzle.
In what way did he solve the puzzle with 299,05,314,003,317

To me the number 300 has to be in the mix someplace because according to the question the compass is 300 yes?
So one way or another if you have the calculated or plotted magnetic course and you have the compass you just subtract to get the D.
So in your solution where is my 300 compass which is the given.

MrA

#### davidpm

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both problems were solve without a chart? answers were 005 and 003 west. That's why I'm perplexed. Since in both problems you are traveling in a north direction and the transit is behind you, solving the problems takes you through 360 degrees and here is where I get lost? anyway the teacher did it without a chart? was it that he knew the bearing? If I plot it on a Rose it still makes no sense to me or am I just going about the process to solving the wrong way thanks
If you know the magnetic of the range then without a chart you can just go west 130 degrees and have a magnetic bearing.
The difference between magnetic and comp is deviation.

But unless you have the bearing of the range in either true or magnetic how do you start to calculate?

Maybe that number was part of the prior problem.

MrA
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