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Old 15-03-2013, 16:53   #1
cruiser

Join Date: Dec 2012
Location: Seattle
Posts: 1,130
OceanGrafix Charts

Just started working with my first order ever of shiny, new OceanGrafix charts.

Distress. Change is bad. New is never good until and unless I like it. Changing the color of my shirt will screw me up for three weeks.

So I'm doing my updates, and find that OceanGrafix uses decimal minutes. That annoyed me. Then I found that it subdivides into sixths of tenths of minutes. That really annoyed me until I realized that a sixth of a tenth of a minute is a second.

Then I went back to using my beloved engineer's ruler trick, which is the way God would have wanted it if She were concerned with navigation.

On a side note, I've been assuming that the Coast Guard publishes the Local Notice to Mariners in degrees, minutes and seconds. Although they carry the seconds out to two decimals, and I'm not sure there's a good reason to do that... and that makes me think I might be missing something.

This does raise another point: I have four charts. Four. Not four dozen, not four hundred, four.

It takes me a long time to read through the Local Notice to Mariners each week-- how on earth do real navigators, with dozens or hundreds of charts to maintain, find time to do all this?

Carry on.
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Old 15-03-2013, 17:14   #2
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Re: OceanGrafix Charts

No. The Coast Guard LNM and Light Lists provide positions in degrees, minutes, and decimal minutes. No seconds.
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Old 15-03-2013, 17:47   #3
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Location: Seattle
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Re: OceanGrafix Charts

Do you have a citation for that?

If it's true, that means that they're using "47-48-53.584" to mean forty seven degrees, 48 POINT 53584 HUNDRED-THOUSANDS OF A MINUTE."

That's a real position from District 13, 08-13.

I don't buy it.

Particularly since in another section of the same notice, the quote mark is used:
47-35-19"

If they are decimal minutes, why are there always two dashes instead of a dash and a decimal point? Why is there a decimal point after the second dash, wouldn't that be two decimal points?

I hope you're not maintaining charts with that assumption.

Does anyone have a citation on this matter?
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Old 16-03-2013, 19:07   #4
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Re: OceanGrafix Charts

Well, apparently they are doing it differently in different areas and for different things. In the past it was always degrees, minutes, and decimal minutes like in this notice from District 1 also 08-13:

Quote:
NY-ROCKAWAY INLET (REVISED 02/13)
Caldwell Marine has deployed vessel anchors and moorings in an area bound by 40-34.121’N, 073-54.122’W; 40-34.155’N, 073-53.955’W; 40-
34.041’N, 073-53.868’W; and 40-34.007’N, 073-54.035’W, southwest of Rockaway Inlet Lighted Buoy 20 (LLNR 34270). A reported least depth
of 25 feet is available in this area.
However, I see what you mean in District 13, when it says this:

Quote:
RELOCATE RELOCATE Coos Bay Entrance Range Rear Light
and Change height to 47 ft.
CHANGE
CGD13
from 43-20-58.530N
to 43-20-58.553N
CGD13
from 43-20-47.039N
to 43-20-47.049N
The light lists are now in this degrees, minutes, seconds and decimal seconds format, so apparently they are changing over. Too bad--I vastly preferred the old system.
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Old 16-03-2013, 23:22   #5
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Re: OceanGrafix Charts

It's annoying to see that they are using different formats in different parts of the company-- that has "error" written all over it. Didn't occur to me to look at another district.

After all, *I* never leave District 13...
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