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the chart is a permanent fixture on the kitchen table, in the AM I will calculate your reply thanksI 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?

I'm using chart 1210Tr...thanks davidpm, rgscpat, jackdale and tempest for helping me thru this, questions are 7 & 8 in the above link.

like tempest I get 60TMr A - what is the true bearing from the monument to the lookout tower.

thanks so much T was the keySolution

T bearing monument to lookout = 060

V = 15W (from my chart - is training chart different?)

M bearing monument to lookout = 075

D = 075 - 070 = 5 E

C = 300 (ships compass) +130 (relative bearing from pelorus) - 360 = 070

So how many of you have a pelorus on board?

I get 359TMy chart shows only one tower

What is the true bearing between the towers?

Jack

T = 359

V = 15 W

M = 014

D = 7 W

C = 317 + 064 - 360 = 021

I get a different answer.[/Quote

Yes, I get the same, I'll double check my line and make sure T was 359, I see what I was missing in your solution thanks

I tried again last night, best I could come up with 000T, I will draw a thinner line a put on better glasses and see what I can come up with thanks3 W is correct...the line is 003 deg.. not 359

on the tests 2 degree error is acceptable, first time I'm doing this and I agree with you the larger the error the farther off course you will be, I can see a lot of factors affecting the results like how thick your lines are, how good your glasses are, how good the light is, if the boat is rocking and of course how many beers you had, if you followed this post from the start, Jackdale asked me the bearing on a line I plotted, I measured it a 359-degrees, Tempest immediately came back with 003-degrees, which was right. I can only hope I will get better with practice, The best I could come up was 001-degree. and I was wondering do sailors even use charts anymore other than emergencies? and would flying and sailing require a similar skill set?I believe a one-degree bearing error at one nautical mile could put you just over a hundred feet off; but a five-degree error starts getting serious at a good 500 feet. With pencil and paper charts, a one-degree error seems quite easy to make.

this is me now and I enjoy putting pencil to paperI use paper charts to do my planning and plotting. I also know how to use electronic charts (I have three different ones on my Windows tablet). I also know how to use radar fix on paper charts.

Explain radar fix?

I may be an exception. Believe I will be also

Being able to paper charts is a skill that should be learned before one starts to use the electronics

excellent thank you

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