Nautical chart measurements???

[andrewsterling]

Hello. New to this site. I'm wracking my brains trying to work out degrees, minutes etc. I though I had it sussed, until I seen the coordinates of New Zealand, which is 40.9006⁰S 1748860⁰E. Now, in my concrete thinking, tunnel vision mind, I'd interpret that as , 40 degrees, 90 minutes, 6 secs. But what I don't get is, if there is 60 minutes in a degree, then why does it not read 41⁰30'06". You'd think if it went over 60 minutes, you'd roll over to the next degree. Can anyone explain this to me, as the answer is probably staring me in the face, but I'm just not getting it. Thanks

[thinwater]

Originally Posted by andrewsterling

Hello. New to this site. I'm wracking my brains trying to work out degrees, minutes etc. I though I had it sussed, until I seen the coordinates of New Zealand, which is 40.9006⁰S 1748860⁰E. Now, in my concrete thinking, tunnel vision mind, I'd interpret that as , 40 degrees, 90 minutes, 6 secs. But what I don't get is, if there is 60 minutes in a degree, then why does it not read 41⁰30'06". You'd think if it went over 60 minutes, you'd roll over to the next degree. Can anyone explain this to me, as the answer is probably staring me in the face, but I'm just not getting it. Thanks

Decimals. Same with GPS. Minutes and seconds are inefficient if doing math. Really, the the D/M/S representation is just quaint.

[andrewsterling]

Ahh. Get you now. So it's more metric based on a GPS. Thanks for that. I can relax now.

[bil56]

paper charts or digital charts on gps plotter ?
if digital maps, it all depends on the configuration of your plotter

./.

[andrewsterling]

I found the information on Wikipedia regarding coordinates for New Zealand.

[Orion Jim]

https://www.fcc.gov/media/radio/dms-decimal
Handy converter…

[Cwens]

There are 3 conventions.

1. Degrees, Minutes, Seconds: 41⁰30'06".
2. Degrees, Minutes with decimal: 41⁰30.1'
3. Decimal degrees: 41.5017

D/M/S is pretty much obsolete


Decimal degrees are great whenever computers are doing the arithmetic.



Degrees with decimal minutes is intuitively convenient to many people because a minute of latitude is equal to one nautical mile.

[Captain Graham]

Time and chart measurements are very similar.
Time is Hours, Mins and Seconds.
Chart measurements are Degrees, Mins and Second.

Start with time.
You can say 10 and 1/2 hours, 10.5 hours, 10 hour 30 mins or 10:30
They are all the same just using a different way to say it.

So if I say it will take 10.5050 hours to arrive at a location.
I am not sailing 10 hours 50 mins and 50 seconds.
I am saying 10 hour and .5050 hours.
So what is .5050 hours easy 60*.5050 = 30.3 Mins
So what is .3 Mins easy 60*.3 = 18 seconds
So 10.5050 is 10 hour, 30 mins and 18 seconds.
Your clock would show 10:30:18

You have to convert from 10.5050 to 10:30:18

It is the same with chart measurements you have to convert
So 10.5050 degrees is 10 degrees, 30 Mins and 18 Seconds

Hope this helps

[MC2019]

I do nautical chart measurements all the time in my delivery business. My coastal explorer has a distance graph on the left side, just use my fingers as protractors and measure distance, can also be done with the mouse to get distance from the vessel. My galaxy tab pro tablet runs navionics and that has a pretty good measurement tool also.