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Old 10-03-2014, 03:40   #1
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Compass Rose

I've been looking at the compass rose on my NOAA charts of Puget Sound.

Studying them carefully, I see an outer ring that is oriented to true north, an inner ring that is oriented to magnetic north, and then a third ring inside that.

I'm used a magnifying glass, a scale and a drafting machine, and come to the conclusion that this inner ring must be what used to be called "points".

Can anyone confirm this?
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Old 10-03-2014, 04:05   #2
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Re: Compass Rose

Cannot confirm this, I dont have any NOAA charts, (being on the other side of the pond).
Just looked through Bowditch for any clues, and in the glossary section, it defines compass rose as a circle graduated in degrees, and sometimes in compass points.
I have only ever seen the two circles, referenced to true and magnetic north.
What is the edition date of the chart?
How is this inner third circle graduated, there being 32 points on a compass, each point equal to 11.25 degree's
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Old 10-03-2014, 04:06   #3
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Re: Compass Rose

Quote:
Originally Posted by Jammer Six View Post
I've been looking at the compass rose on my NOAA charts of Puget Sound.

Studying them carefully, I see an outer ring that is oriented to true north, an inner ring that is oriented to magnetic north, and then a third ring inside that.

I'm used a magnifying glass, a scale and a drafting machine, and come to the conclusion that this inner ring must be what used to be called "points".

Can anyone confirm this?
I am not familiar with this particular chart, but just count the number of divisions. If it is 16 or 32, this would be known as a "16 point compass rose" or a "32 point compass rose" with each division representing 22.5 or 11.25 degrees respectively. Each of these wind directions is named.
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Old 10-03-2014, 12:59   #4
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Re: Compass Rose

I think there's 64 points. (I'm not looking at it right now.)
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Old 10-03-2014, 13:10   #5
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Re: Compass Rose

If 64, then its graduated in half points.
Old compass cards would be graduated down to quarter points, some info here from wiki
Points of the compass - Wikipedia, the free encyclopedia
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Old 10-03-2014, 19:19   #6
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Re: Compass Rose

I'll double check. Man, what a pain in the ass.

"Where?"

"South South West Three Quarters West, and closing fast!"

{silence}

"What...?"
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Old 10-03-2014, 20:52   #7
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Re: Compass Rose

Quote:
Originally Posted by Jammer Six View Post
I've been looking at the compass rose on my NOAA charts of Puget Sound.

Studying them carefully, I see an outer ring that is oriented to true north, an inner ring that is oriented to magnetic north, and then a third ring inside that.

I'm used a magnifying glass, a scale and a drafting machine, and come to the conclusion that this inner ring must be what used to be called "points".

Can anyone confirm this?
I just checked chart 18474...the inner ring is in fact graduated in points with the smallest divisions being quarter-points of the compass.
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Old 10-03-2014, 21:08   #8
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Re: Compass Rose

Yup, I just looked at 18446, my main axe. There are 128 divisions on that ring.

Yee gods.

I learned to recognize nails, screws and bolt heads at a glance. Then I learned to recognize them when they were by themselves. I was much younger then, and it still took me years.

I just don't want to go through the learning curve. I'll go to sixteen. I can deal with sixteen. But if it has to be finer than that, I think it'll be magnetic degrees for me, then I'll tell you the reading and hand you my binoculars.

"How can we make this harder?"

"Well, instead of 360 degrees, we could go with some other random number, say, every two and half degrees, then we could give them some other names, then to really screw people up, we could add a separate scale for the compass and another random North. Then, oh, I know, oh, I know, we could mix all three into orders!"
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Old 10-03-2014, 22:52   #9
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Re: Compass Rose

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Originally Posted by fryewe View Post
I just checked chart 18474...the inner ring is in fact graduated in points with the smallest divisions being quarter-points of the compass.
Yep.

And the sidelights are visible through dead ahead to 2 points abaft the beam.
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