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CA Regulations / Re: Navionics: 20fm waypoints/line setup
« on: April 07, 2024, 10:21:21 PM »Those aren't dd-mm-ss, they are dd-mm.mm
It is measured in tenths of minutes, not in seconds, if that makes any sense. GPS is silly sometimes - many different users (ships, sailboats, airplanes, car navigation, etc) use different integers to depict the same position. Most common that I've seen are: dd.ddddd (Google maps and a lot of terrestrial users), dd-mm-ss (sail boats, some charts), dd-mm.mm (most commercial mariners, most navigation charts). There are also a few other systems with specific ideas that not many people use. Most modern devices let you choose which system you are most used to, between the three that I exampled anyway.
"Should the last part of the latitude (39°25.53'N) be entered as 053 or 530? Or what?"
So what's the answer? The navionics app, for lat. has 2-digits in the first spinwheel, 2-digits in the second, and then there are three more spinwheels with 1-digit (0-9) in each. See my post above for the screenshot. Do I have to do a conversion from dd-mm-ss to dd-mm.mm before entering into Navionics? But then the number of digits in the interface is 7 instead of 6. So confused.
I finally got it figured out. The way-point map on the CDFW site...
https://wildlife.ca.gov/Conservation/Marine/Groundfish#287201301-20-fm-line
... lists two lat/long coordinate formats for each way-point:
lat_dd/long_dd (aka Decimal Degrees)
lat_ddm/long_ddm (aka Degrees Decimal Minutes)
Neither of which were the format I was basically familiar with (Degrees, Minutes, Seconds) and I had no idea there were other formats in use.
The Navionics App uses ddm, but it's confusing because they don't label it as such and they have 3 digits at the end of the number string on their coordinates-input screen, while the coordinates provided by CDFW only have 2. For example, for a CDFW-provided 6-digit ddm longitude of 39°12.19'N, Navionics has 7 characters to select (with only the 6 provided by CDFW), and then the question is what to do about that. The answer turns out to be just use a ZERO in the last position/selector.
Handy coordinate format converter:
http://www.csgnetwork.com/gpscoordconv.html
Issue solved.