Lat and Long arithmetic

[tubber]

When I get to Ukee on Friday, I will go find my boat and write down a few of the spots on my Lowrance so we can use them on a friend's boat with a Garmin if he wants.
My unit has the lat/long in degrees, minutes, then decimals.
His unit has degrees, then decimals.
So to use one of Charlie's old tips: Turtle Head / Ucluelet and Tofino/ N48 50.531 W125 30.787
I would need to divide the 50.531 and 30.787 by 60 to get N48.84218 and W125.51312
If I was using his spots, I would need to multiply the decimal part by 60 to get minutes then decimals.
I bring this up because once I texted him some numbers for a hali spot and neither of us realized the minutes/decimals difference and he didn't find the place.
More importantly, he volunteered to go find someone who ran out of fuel to tow him in, and once again the numbers from the coast guard and his unit didn't match and it took longer than it should have to offer assistance to a stranded vessel.
It can be many miles difference if both parties are not using the same system.

 

[Kildonan]

Can he switch the units of display to the same as your GPS? I know I can change that setting in my handheld Garmin.
I've never even looked at the plotter I use to see what it's using or if I can change that setting.

 

[tubber]

So far not. What is the most common these days? Tugcaptain or others on the water daily?

 

[agentaqua]

For chartwork and chart corrections, and NOTSHIPS and NOTMARS - degrees, minutes, seconds. For most GIS software - degrees and decimal degrees. The better software can easily convert back 'n forth with the hitting the right tabs in the preferences/units. There are also online, and stand-alone converters available.

 

[CIVANO]

A lot of info but lon/lat paragraph half way down might help
http://www.gpsinformation.org/dale/measure.htm

 

[CIVANO]

another one telling a little about changing the selection

http://www.leeroysramblings.com/GPS.htm

 

[bones]

Export it to a gpx file on a SD card. Willing to bet the Garmin will convert the addresses no proplem

 

[Tugcapitan]

So far not. What is the most common these days? Tugcaptain or others on the water daily?

Sorry I'm late just saw this.
I was interested to see your first post refer to degrees going right into decimals (48.84218), that's unusual.
In my experience it's always either
48*50.531 (48 degrees, 50.531 minutes)
Or
48*50'32" (48 degrees, 50 minutes, 32 seconds)

Like you say, to convert seconds into a decimal of the minutes divide by 60 and vice versa.

I guess it would work as well with minutes to express minutes and seconds as a decimal of the degree, but it's not usual, and like you say could put someone who was confused miles away!

 

[tubber]

thank you. I have one more trip with him next week after a few days on my boat. We'll get into his Garmin set-up and try to change it. Or keep doing math.