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What's your Lat & Long?

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britinusa
Web Editor

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USA
5404 Posts

Initially Posted - 11/17/2007 : 07:19:05

Quiz:
How do you find out your Lat & Long (where you are right now!)

Mine is lat = 26.25058419297508, long = -80.20283460617065

Paul

Joint Decision. (Sold)
PO C250WB 2005 Sail # 841.

Moved up to C34 Eximius

Updated August 2015

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 11/17/2007 : 07:46:50

You turn on your GPS... (Ding!) Mine is in the car right now, but my slip outside is at N41-22.692 W71-57.752 (degrees and minutes). I'm sitting about 100 yards SE of there.

Edit: Google Earth shows me sitting at N41-22.672 W71-57.676. (Scary!)

Edited by - Dave Bristle on 11/17/2007 08:10:51

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 11/17/2007 : 08:17:02

BTW, does anyone know which nomenclature the Coast Guard prefers for voice communication of lat-lon? Do they prefer decimal degrees, degree-minute, or degree-minute-second? I'm guessing the first, but haven't set my equipment that way.

Edited by - on

EAbrams
Navigator

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USA
130 Posts

Response Posted - 11/17/2007 : 09:05:10

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Dave Bristle
 Do they prefer decimal degrees, degree-minute, or degree-minute-second?
<hr height="1" noshade id="quote"></blockquote id="quote">
My knowledge of GPS stops at " That triangle on the screen is us"

Why are there two or three different ways to measure location. It escapes me. I have typed in coordinates exactly as they are given and a lot of times the waypoint is off. Anyone know why?

Edited by - on

Dave Bristle
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Djibouti
10005 Posts

Response Posted - 11/17/2007 : 10:01:58

The three types are for the same actual values:

- Degrees, minutes (60 per degree), seconds (60 per minute)
- Degrees and minutes with decimal fractions (like I used above)
- Degrees with decimal fractions (like Paul used above)

A GPS can be set to display any of these, as can MapSource, Google Earth, etc. But you should be sure that you're not typing decimal fractions of minutes where seconds are expected, minutes where fractions of degrees are expected, etc.

Edited by - Dave Bristle on 11/17/2007 10:07:34

piseas
Former Treasurer

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USA
2017 Posts

Response Posted - 11/17/2007 : 10:06:56

Paul, Ditto on GPS. But check out this site. You can type in address for that exact info.
http://jan.ucc.nau.edu/~cvm/latlon_find_location.html
I am at Lat-Long:
33.65 (33°39') | -117.90 (-117°53')
Steve A

Edited by - piseas on 11/17/2007 10:09:27

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 11/17/2007 : 10:11:24

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by piseas
 You can type in address for that exact info.<hr height="1" noshade id="quote"></blockquote id="quote">Not quite right for me... (It puts me in a cemetary. Don't bother..... )

Edited by - Dave Bristle on 11/17/2007 10:12:30

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 11/17/2007 : 10:42:58

OK so I tried it and now there are black helicopters outside.

Edited by - on

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 11/17/2007 : 11:10:03

Round here, it would be better to tell the USCG or Vessel Assist your lat / long in degrees minutes.decimal minutes.

No one uses seconds.

Some one collect all the responses and map them.

I am near enough to 33 0.00 -118 0.00

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 11/17/2007 : 12:24:01

[url="http://www.frappr.com/catalina25owners"]Catalina 25 Owners[/url]

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Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 11/17/2007 : 13:26:32

Google Earth.

Edited by - on

stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 11/17/2007 : 14:53:11

There are about 34 members on the Frappr site

per Don's link above.

Edited by - on

Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 11/18/2007 : 09:04:01

The Coast Guard rescues enough jackasses day in and day out. If you actually have GPS coordinates and it is an emergency they are probably very happy you even know where the heck you are and not too concerned with how you read off the coordinates.

In the case of an emergency I can't see them say "sorry captain, but we don't accept coordinates in decimal form. Please convert to degrees, minutes, seconds and thousandths and re trasmit your location at that time."

Edited by - Champipple on 11/18/2007 09:09:28

Derek Crawford
Master Marine Consultant

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USA
3321 Posts

Response Posted - 11/18/2007 : 17:37:03

I'm at: N 29 41.570 W 98 39.632

Edited by - on

Tom Potter
Master Marine Consultant

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USA
1913 Posts

Response Posted - 11/18/2007 : 18:33:53

Knotty Cat's future home is;
N 35 25.790
W 076 39.310

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 11/18/2007 : 18:51:41

<blockquote id="quote">quote:<hr height="1" noshade id="quote"> The Coast Guard rescues enough jackasses day in and day out. If you actually have GPS coordinates and it is an emergency they are probably very happy you even know where the heck you are and not too concerned with how you read off the coordinates. <hr height="1" noshade id="quote"></blockquote id="quote">

Actually they'll probably quiz you very closely about your position and ask specific questions about your readout. I made this example in Google Earth using the same coordinate values in both degrees-minutes-seconds & decimal degrees (two common readouts). As you can see, they're over 17 miles distant from each other. This would make a huge difference to their response time if you read them off as degrees-minutes-seconds when you have your GPS set to another coordinate display system.

This is a very good case for having DSC attached to your VHF because it handles all this for you and simply shows your position to the receiving set w/o you having to say a word.

BTW we're at:
47°44'33"N
121°59'04"W

Edited by - delliottg on 11/18/2007 18:54:57

Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 11/18/2007 : 19:19:50

My GPS is on the boat, so I don't have a clue where the heck the house is...however the boat is normally here 41 29 36.38 N 81 43 55.09w

If any of you have Google earth on your PC the Pic at that location the view from the cockpit of my boat - (in this case my old C-25)

Edited by - on

glivs
Admiral

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USA
836 Posts

Response Posted - 11/18/2007 : 20:09:04

I agree that DSC is the answer but otherwise Dave Bristle's original question is a good one. From what I've read, in the days immediately following Katrina's wrath the various local, state and Federal agencies using different approaches, projections (street names vs. UTM vs. lat/lon)and formats to communicate locations between air and ground crews led to a great deal of confusion. Delliottq's example is also interesting. Format differences do not inherently result in location differences; the error arises in that different spatial precisions were entered. If round-off error doesn't get in the way, conversion between any of the three formats should be exact.

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 11/18/2007 : 20:34:16

You're correct in that format differences don't cause errors in positions, it's when one person is using one format, and another is using a different but very similar format and thinks the position is in their format. That's how I came up with my 17 mile example. Rounding errors in the same format will only move your position slightly and you'd probably be in visual range.

I don't know if the USCG has a "preferred" format, and I wonder what DSC transmits (I'll do research on this). I think if the USCG has a preferred format, I'd probably set my GPS display to that format to eliminate that as an error. I've shown Rita how to get the to "right" screen on the GPS should she ever have to transmit our position. She's confident she can get to it, but who knows what happens when the adrenalin's pumping, the boat's rocking and I'm hurt or in the water? Once I have our new VHF setup and installed, it also displays your location, so in case DSC fails for some reason, she'll still be able to just our position off of the faceplate of the radio.

Getting further OT, another possible problem is cursor location. You can move your cursor around on your GPS screen and get Lat/Lon on the cursor's location, not yours. I've read several accounts on this happening when rescue people are looking for someone who's given them the location of their cursor and they're actually located miles away.

Edited by - on

Russ.Johnson
Commodore

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USA
855 Posts

Response Posted - 11/18/2007 : 21:52:02

N 37.44.7885
W -121.57.0463

Edited by - on

EAbrams
Navigator

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USA
130 Posts

Response Posted - 11/19/2007 : 08:44:11

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by delliottg
 You're correct in that format differences don't cause errors in positions, it's when one person is using one format, and another is using a different but very similar format and thinks the position is in their format. That's how I came up with my 17 mile example. Rounding errors in the same format will only move your position slightly and you'd probably be in visual range.
<hr height="1" noshade id="quote"></blockquote id="quote">

I see now that others have experienced the same problem I did.

My earlier post
Why are there two or three different ways to measure location. It escapes me. I have typed in coordinates exactly as they are given and a lot of times the waypoint is off. Anyone know why?

Edited by - on

DaveR
Master Marine Consultant

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USA
2015 Posts

Response Posted - 11/19/2007 : 11:09:31

I'm at 29 11 00.87 N 81 00 17.29 W

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 11/19/2007 : 12:29:35

David's 17 mile discrepancy illustrates perfectly the reason for my question. Voice communication in an emergency can be dicey, and DSC won't help other boats without DSC to come to your rescue. My GPS offers user-selected data fields on the display--I selected lat/lon as one of them so no matter where the cursor is, that field shows my position. If I'm communicating with somebody in the fog, I can move the cursor to his position (the cursor lat/lon displays at the top) and tell him what mine is (displayed on the side).

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Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 11/19/2007 : 13:55:16

David, the Coast Guard does not dispatch rescue craft to Federal Way.

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delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 11/19/2007 : 14:03:16

Exactly my point.

Since we're a bit off topic, I'm starting a [url="http://www.catalina-capri-25s.org/forum/topic.asp?TOPIC_ID=16585"]new thread[/url] about reporting your position to vessel assist or the USCG.

Edited by - delliottg on 11/19/2007 16:28:55

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