1 Minute = 60 Seconds?

[Rockinar]

If theres 60 seconds in 1 minute, Why is there only 10 seconds in this minute?

What am I not getting? Its late and Im confused.

[HankOnthewater]

Indeed a minute on a clock has 60 seconds.
And indeed, in theory at least, coordinates can be expressed with degrees, minutes and seconds.
A minute on charts is generally expressed in decimals of minutes, hence the division you see in your pic.
It looks like the pic is from a chart and measuring longitude (at the bottom and top of the chart).

That is my simple explanation. There is a way of converting degrees, minutes and decimal minutes to degrees, minutes and seconds. That and a better explanation can be found here: https://eoceanic.com/sailing/tips/35...g_a_waypoint/?
I have not seen anyone using seconds in coordinates and navigation.

[cal40john]

Or you could - 60 seconds/minute there are 10 marks per minute, so 60/10 = 6, so each mark is 6 seconds.

Count by 6's.

[Rockinar]

Originally Posted by cal40john

Or you could - 60 seconds/minute there are 10 marks per minute, so 60/10 = 6, so each mark is 6 seconds.

Count by 6's.

Ok that makes sense. I was counting 1s. Mystery solved!

[El Pinguino]

Originally Posted by HankOnthewater

Indeed a minute on a clock has 60 seconds.
And indeed, in theory at least, coordinates can be expressed with degrees, minutes and seconds.
A minute on charts is generally expressed in decimals of minutes, hence the division you see in your pic.
It looks like the pic is from a chart and measuring longitude (at the bottom and top of the chart).

That is my simple explanation. There is a way of converting degrees, minutes and decimal minutes to degrees, minutes and seconds. That and a better explanation can be found here: https://eoceanic.com/sailing/tips/35...g_a_waypoint/?
I have not seen anyone using seconds in coordinates and navigation.

What he said ^^^^
'seconds of arc' are so very much yesterday.
These days every real fair dinkum navigator uses minutes of arc and decimal minutes - as shown in your example.

[Rockinar]

Originally Posted by HankOnthewater

I have not seen anyone using seconds in coordinates and navigation.

So ignore seconds when using DMS except maybe in really small scale charts?

[Rockinar]

Originally Posted by El Pinguino

What he said ^^^^
'seconds of arc' are so very much yesterday.
These days every real fair dinkum navigator uses minutes of arc and decimal minutes - as shown in your example.

Electronics spit out decimal minutes. Then you have to convert that to DMS. So just ignore that S after you convert?

[SeanPatrick]

Originally Posted by Rockinar

So ignore seconds when using DMS except maybe in really small scale charts?

Depends on the accuracy of your measurements. But really, what is the largest scale you will practically need? That is the question.

[Benz]

I prefer Deg/Min/Sec, but the sight reduction tables are published in deg/min/tenths, so I had to adapt. Tenths are bigger chunks than 60ths, but when it comes down to the plotting sheet, that difference is tiny enough to be insignificant.

[StuM]

Just forget about seconds, only dinosaurs still use them .


Decimal minutes are easy to work with and visualise.
1/10th of a minute* (0.1') is roughly 200 yards or metres
1/100th (0.01') is roughly 20 yards or metres.


*on a line of latitude / great circle , or close to the equator

[ChrisJHC]

Originally Posted by StuM

Decimal minutes are easy to work with and visualise.
1/10th of a minute* (0.1') is roughly 200 yards or metres

Also known as a cable.

[AiniA]

Originally Posted by ChrisJHC

Also known as a cable.

Is that a metric cable or an imperial cable?

[carstenb]

Originally Posted by ChrisJHC

Also known as a cable.

What size links?

[CaptTom]

Going back to the days of paper charts (without arguing their value or lack thereof), you should be aware that some charts use DMS, while others use decimal minutes. A common mistake is to forget to check which units the chart is marked in.

Seems all the skills I've developed become obsolete just about the time I get good at them!

[billgewater]

Historically, the base 60 system seems to have appeared with the Sumerian cuneiform number system. It has been around for a while (4000 yrs?) and we use it in both our watches as well as our navigation. A feature of the base 60 system is that 60 is divisible by 2,3,4,5,6,10, 12,15, 20 and 30. Poor old 10 is divisible by 2 and 5 only. Plus 6 of these make up 360 degrees- handy in geometry and building. (The cuneiform number system uses a simple symbol for 1 and a broader horizontal shaped V for 10, so internally it uses a crude clumsy cumulative decimal system.)
Even after the Hindi number system was adopted in European trade (see Fibonacci etc.), the application of the base 60 system was still superior for navigation and speed was still derived around covering seconds of arc on the chart and the measured time intervals.
A speed of one knot was (still is) equivalent to covering I minute of latitude (a nautical mile) in one hour. All very much based on 60.