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Old 21-07-2010, 10:28   #1
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NM -> M

How about change NM to M (Nautical Mile -> Mile) in OpenCPN? In my school, we always use M as in nautical mile.
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Old 23-07-2010, 00:52   #2
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considering that most of the planet thinks that "M" is a meter, that a plain "mile" is a statute mile, and are not so thick as to consider that a navigation program could be using nanometers as a unit of measure, unless I am mistaken I'd say your school is teaching very dangerous lessons.
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Old 23-07-2010, 01:33   #3
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Quote:
Originally Posted by HamishB View Post
... unless I am mistaken I'd say your school is teaching very dangerous lessons.
That was my first thought, too.
But when believing in what Wikipedia says (Nautical mile - Wikipedia, the free encyclopedia):
Quote:
The International Hydrographic Organization, whose membership includes essentially all seafaring nations, and the International Bureau of Weights and Measures use M as the abbreviation for the nautical mile.[1][9] The preferred abbreviation of the International Civil Aviation Organization is NM.[10] The abbreviation nm, though conflicting with the SI symbol for the nanometre, is also widely used. The SI symbol for the newton metre is N m.
it would be correct.

Personally I prefer NM. One point where we have no problem in German as we use 'sm' for nautical mile. Though on the inland waterways and lakes 'km' (Kilometers) is used as the standard unit and also 'km/h' instead of knots.

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Old 23-07-2010, 02:55   #4
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Originally Posted by HamishB View Post
considering that most of the planet thinks that "M" is a meter, that a plain "mile" is a statute mile, and are not so thick as to consider that a navigation program could be using nanometers as a unit of measure, unless I am mistaken I'd say your school is teaching very dangerous lessons.
Vedis is absolute correct. M has been the internationally recognized abbreviation for at least 25 - 30 years, but nobody uses it much, and are not even aware of their own local standard

Symbols, Terms, & Abbreviations Used on Charts

Lets have a look at INT 1 section B
No 41 : m Meter(s)
No 45 : M Nautical Miles.....

The question is rather, is there any major seafaring nation that don't accept these abbreviations formally, .. and is there any nation that actually use M in real life? (Perhaps Finland ?)

This is not a big deal at all, but to me a "mile" is a nautical mile.
If the landlubbers want to persist in their centuries old misunderstanding of the size of Earth, and insists that a mile is 1609 m instead of 1852 m, I just ignore it

Thomas
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Old 29-07-2010, 07:31   #5
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Hello,

on NOAA chart 18665_1.kap there is a List of abbreviations:

...
M Nautical Mile
...

I vote for M

(note that the abbreviation for meter is "m", as for minute...)

Ciao, Marco.
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Old 29-07-2010, 07:58   #6
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I vote for M
I vote for NM.

I believe that it is less confusing espacially for users from countries where miles are not the standard unit.

As we also have meters and kilometers as units in OCPN it may irritate.

Quote:
(note that the abbreviation for meter is "m", as for minute...)
IMHO we should use what (most) people are used to.

For example in German it is "Seemeile" = sm, which is close to "Nautical Mile" = NM.

Gunther
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Old 29-07-2010, 08:19   #7
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just a little thought experiment: could you imagine an airline regulatory body allowing such an ambiguous abbrev. as "M" to continue to be used? (well actually pilots are so strictly licensed and trained that maybe they could get away with it)

it's just plain dangerous.
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Old 29-07-2010, 09:02   #8
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Since we cannot agree on an appropriate abbreviation for the nautical mile; perhaps, we should revert to the league.
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Old 29-07-2010, 10:31   #9
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Bring back fathoms, you knew where you were with fathoms and while we're at it, where did the lead line and tallow disappear to?
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Old 03-10-2010, 04:56   #10
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Originally Posted by Netsurfer View Post
I vote for NM.

I believe that it is less confusing espacially for users from countries where miles are not the standard unit.

As we also have meters and kilometers as units in OCPN it may irritate.

IMHO we should use what (most) people are used to.

For example in German it is "Seemeile" = sm, which is close to "Nautical Mile" = NM.

Gunther
I agree strongly with Gunther.
The official abbreviation as used in official publications in Europe is nM = nautical Mile.
At my marine study for captain we learned nM.
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Old 03-10-2010, 07:06   #11
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Bring back fathoms, you knew where you were with fathoms and while we're at it, where did the lead line and tallow disappear to?
Fathoms were usually used for depth measurement.
I still have my lead line(s).
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Old 03-10-2010, 07:26   #12
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I agree strongly with Gunther.
The official abbreviation as used in official publications in Europe is nM = nautical Mile.
At my marine study for captain we learned nM.
I agree, as well.

I think maybe the test should be: which will not confuse anyone?

M may be technically right in most of the world, but can it confuse anyone? Yes.

Would NM (or nM) confuse anyone? I don't think so. Would it?

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Old 03-10-2010, 08:00   #13
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Fishwife... I think you maybe mean cables.... 1 cable = 1/10 of a nM
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Old 03-10-2010, 08:52   #14
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Suggestion - add options for the user to set the display value for each unit of measure.
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Old 03-10-2010, 09:28   #15
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1. From:
REGULATIONS OF THE IHO FOR INTERNATIONAL (INT) CHARTS AND CHART SPECIFICATIONS OF THE IHO

B-130 UNITS
The standard units for depths and heights must be metres (m) and decimetres (dm). The standard units for positional accuracy must be metres (m). The standard units for distance ‘on the ground’ must be nautical miles (M) and cables, or metres (m). The standard units for dimensions of charts must be millimetres (mm). The standard units for time must be hours (h), minutes (min or m) and seconds (sec or s), referred to Universal Time Co-ordinated (UTC). The standard units for speed must be knots (kn). The standard units for geographical positions should be degrees (°) minutes (') and decimals of a minute. Degrees (°), minutes (') and seconds (") may be used if appropriate. The standard units for bearings, such as for a recommended track or magnetic variation, should be degrees (°) and decimals of a degree. Degrees (°) and minutes (') may be used if appropriate.

B-131 GEOGRAPHICAL POSITIONS
Geographical positions quoted on charts and in related publications should be:
• expressed in degrees, minutes and decimals of a minute
• with a single space between the coordinates and no other spaces
• without punctuation
• with a decimal separator according to national practice (comma, decimal point or full stop – comma is the preferred ISO sign)
• with leading zeros for single number minutes, but not for degrees
• with the minute tick following the fractional part eg: 51°42,03'N 5°07,14'E 51°42·03'N 5°07·14'E 51°42.03'N 5°07.14'E

Exception:
• Degrees, minutes and seconds may be used if the graduation of the chart concerned is in that format, to avoid confusion.

B-131.1
The four cardinal points must be denoted by the following abbreviations whenever their names are not inserted in full:
North = N
South = S
East = E
West = W

2. And the ISO says (ref. ISO 19018:2004; https://cdb.iso.org/cdb/termentry!di...857&language=1):

1 NM = 1852 m. The nautical mile is not an SI-unit. This definition was adopted by the First International Hydrographic Conference in 1929
(see ISO 31-1).
International symbol for unit: NM
International symbol for unit in charts: M [Symbol M is to be used in Charts according to the "Chart Specifications of the IHO" which came into force at the XIIth International Hydrographic Conference 1982 in Monaco.]

So my conclusion is:
For chart data M should be used, in all other cases (e.g. the status line of OpenCPN) NM should be used.
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