GPS grid...

[Skipper]

I was wondering if there is a good way to "pinpoint" a spot on a lake with a GPS grid. I have a map of a very large local lake that has a grid on it, and I would like to program the coordinates of a spot into my GPS.

For instance lets say I want to go to Nine Mile Flat. It is impossible to sight from shore because as the name suggests, it is nine miles out. It is north of 46*14.000', south of 46*15.000', east of 93*40.000', and west of 93*39.000'. I am familiar with my GPS unit, and once I can put a number on the spot I will have no trouble. What do these numbers mean? How can I pull a coordinate off of this grid with any amount of accuracy? Is half way between 46*14.000' and 46*15.000', 46*14.500'?

I would Like to own a mapping GPS, but my Garmin GPS 72 will have to do for now.

[Skipper]

My goal in this is to plot points on my GPS in my free time at home to maximise the time I spend fishing on the water. I have had great success with this when I have pre calculated coordinates already supplied by the cartographers that make the maps.

Listed on the margin of the map are the coordinates of "The Graveyard". I plug N 46*09.910' W 93*31.090' into my GPS, and drive right to it. I punch a hole, and I am right on it! I would like to do this with spots that don't have the coordinates listed.

[oldwolf]

The book GPS Made Easy, 4th Ed, written by Lawrence Letham , has all the information you need to  get Latitude (East-West) and Longitude (North-South)  from maps with grid lines. The process consists of subdividing the grid into numbers that are GPS compatible. It takes a little practice and can be confusing at first. Best learned with book in hand, or from someone who can walk you through it step by step. Book costs $15.95  and should be available from Barnes and Noble or any large outdoor store. Oldwolf

[IceRover]

I was wondering if there is a good way to "pinpoint" a spot on a lake with a GPS grid. I have a map of a very large local lake that has a grid on it, and I would like to program the coordinates of a spot into my GPS.

Skipper, I’m not sure but I think you are wanting to create a waypoint known as a reference waypoint. If you use the closet known waypoint that you have to the area, or one on the map you could figure it out by using your compass on the map to get a bearing, (degrees), and also using the scale of the map to get the distance from your known waypoint. By entering the bearing and distance from the known waypoint you will get the reference waypoint. I have a older GPS 12 and I will enclose the instruction here. Hope this is what your looking for and that your unit has the same feature, if not, sorry. I do not have a grid map but use this feature all the time using bearing and distance from scale. On the ice or land I use a compass and rangefinder for shorter distances.
 
To create a new waypoint manually without knowing its position coordinates, you’ll need to enter its bearing and distance from an existing waypoint or your present position.
To create a new waypoint by referencing a stored waypoint:
1.  From the waypoint definition page, highlight ‘NEW?, and press Enter.
2.  Enter a waypoint name, and press Enter.
3. Highlight the ‘reference’ field, and press Enter.
4. Enter a reference waypoint name(or leave the field blank to use your present position, and press Enter.
5. Enter the bearing and distance of your new waypoint from the reference waypoint.
6. Press Enter to confirm the ‘Done’ prompt.

[fozsey]

The only accurate way i know to do what you want to do is from a computer. If you have the data cable and the Garmin mapping software you can pinpoint locations on the computer map and transfer those to your unit. I have never tried it but I think that is the only way you can, or at least with the etrex that I have. The mapping program I have is called Map Point Metro Guide. It is a little primitive in terms of mapping but in terms of visual location references it works great. Other than that, its a guess at best.

[Webguy]

What do these numbers mean? How can I pull a coordinate off of this grid with any amount of accuracy? Is half way between 46*14.000' and 46*15.000', 46*14.500'?

The numbers North are degrees above the equator and the numbers West are degrees west of prime meridian.
Your estimates will only be as good as the map detail and without minutes in decimal (or seconds) on the map you're not going to be very accurate.
North 46 degrees 14.000 minutes or N 46 deg.14 min. 0 sec. (can also be notes as N46*14'00").
And yes, half way is .50 minutes (or 30 seconds).

Here's some actual distances you're looking at:

A degree of latitude is approximately 69 miles, and a minute of latitude is approximately 1.15 miles. A second of latitude is approximately 0.02 miles, or just over 100 feet.

A degree of longitude varies in size. At the equator, it is approximately 69 miles, the same size as a degree of latitude. The size gradually decreases to zero as the meridians converge at the poles. At a latitude of 45 degrees, a degree of longitude is approximately 49 miles. Because a degree of longitude varies in size, minutes and seconds of longitude also vary, decreasing in size towards the poles.

[justaboutgeese]

You should be able to just pop the longitude and latatude into your GPS and save them as way points.  That being said be aware that many GPS systems are good in many cases to within 50 feet or less,  The accuracy of many, many maps in circulation are not as accurate as we would like.  In most maps there are glaring errors we never would have suspected without having a GPS to verify that Long and Lat on the maps are off by rather large margins.  If this turns out to be the case when you actually get to the entered way points you will have to make a notation on your map . 

[PigShanks]

Google Earth!!!! Find the area on the lake you want to fish on Google Earth and the Co-ords are right there. Punch them onto Mr. GPS and your set!!! Some of the images on Google are even clear enough that you can see the weed lines(at the time when the image was taken)!

[Lobes]

I've found that most grid maps are set up to UTM coordinates rather than minutes / degrees. I switched my setup to UTM's long ago. This is alot more accurate anyway.

                                               

[Skipper]

You guys are gods!!!!!! I don't even know where to start!!!!

Ice Shanty rules!!!!!

[TMBWarriors]

Hey Skipper i have a rhino 120 and i bought the greatlakes blue chart and the topo chart they are awesome.First the topo map is very helpful in finding certain areas that i want to hunt and with the mapping software i can preload any spot that i want to go to.I then go to that spot and when i return home i download all my waypoints and bread crumbs "your exact route of travel".From there i can add any waypoints  or create a route to that certain area.This is not one of the easiest things i have ever done and with a little practice it gets alot easier.Transferring data to my gps and back to my mapping software is very easy and i have made many maps from that days travel after i print it out.You will have to erase your breadcrumbs if you use it alot,but if you transfer it back to your computer you will have a file that can be printed any time you want.The blue chart has the same features as the topo and after a day of fishing i transfer everything back to the computer and create a file.This is hard to explain but with the manuals and a little practice it is awesome.Pm me if you need any info.Hope this helps.

[rondog]

Garmin  has MapSource softwear that is real easy.Connect your GPS to the computer,bring up your destination on the the screen hit download and it goes to your GPS.The maps are good except they don't give you depths so there is no bottom reference.PigShanks Google idea will work at least as good

[Skipper]

Can I use mapping software with my GPS 72? Everything is so vague on the subject. I went to the Garmin website and it says the mapsourse software is no longer available. If I could do the figuring on my PC and then load the coordinates on the GPS that would be great. I went to Google Earth, and man is that cool! I found people I know places and I could count the cars in their driveway! I could see the bottom in most of the clearer lakes! I got the coordinates of a few of my favorite spots!

[PigShanks]

Are you able to hook up yor gps to a computer? Check out the software link. This will allow you to load the waypoints from the pc to the gps. PM me if you have any questions.


http://www.easygps.com/

[Skipper]

I do believe I can attach my gps to my PC. There is a four pin plug in the back of my GPS. There was no cord included when I bought it, but I will check Cabelas out tomorrow. If cabelas doesn't stock it, they can get it.

[Hollywood703]

try google earth, if it has the detailed map for your area projected you can get damn close.....most rural areas arent done, however it will get you within a few 100 ft.

[dabluz]

Yes, you can use the grids on maps and plot them to your Garmin.  Just change the settings from UTM or other that you are using in your Garmin.  From what I know of grids, they are a specific size (say 1000 by 1000 feet) and each grid has a number in reference to the grid number in the upper left hand corner of the map.  Once inside the grid you are looking at, you can estimate to within a hundred feet the number that you can enter into your Garmin.  You can even buy a small plastic protractor that further divides these grids more accurately.

I have an old Lowrance and it does not have this "military grid".

I'm not an expert at this, I just looked at the possibilities of doing this when I had an old Garmin 45 and I had some military maps.  But, I didn't get a chance to play around with this.