Meridian Gold North reference

[Bronson]

I have two meridian gold gpsr's and I was wondering if I need to change the north reference to true north for map(topo) work? I don't understand and I need someone to dumb it down for me. I realize that there is a difference between true north and magnetic north but what I don't understand is there uses. Will the topo map coordinates be easier to get with UTM and that's another concern? My gpsr also has military north and military magnetic north.

Thanks,

Paul

[+embra]

True north probably works best; that way you don't need to worry about making adjustments for declination...the GPS does it for you.

 

If you are working with a map and it has UTM on it, then UTM is the easiest way to find your position on the map. You may want to pick up one of those little grid tools in the right scale. There's a nice online tutorial on that page, too.

[+twolpert]

If you plan to measure bearings on the map and transfer them to the unit (or vice-versa), true north is easier to use. As embra points out, this avoids the need to correct for declination on the map. Whether you use lat/lon or UTM, there is still likely to be a difference between true north and grid north. This will be marked in the margin of the map.

 

If you are using the unit for geocaching, you also need to pay attention to the true/magnetic north setting on the unit when you do multis which require waypoint projection. In this type of multi, you will have instructions such as "go 750 feet on a bearing of 270 degrees magnetic (or true)". In this case, it is very important to set the unit to match the instructions before you project the waypoint. As embra also points out, the unit can compensate for local declination. But in order to do so, it must know whether you are entering a true or magnetic bearing.

 

Finally, if you use your unit in conjunction with a regular compass (as opposed to an electronic compass built into the unit), you may find it easier to use magnetic north in the field. This is especially true if you use a cheaper compass that does not have an adjustment for declination. This makes it very easy to transfer the bearing to the next waypoint from the unit to the compass. Not sure why you'd want to do this as opposed to following the pointer on the unit, but thought I'd mention it in the interest of completeness. We used to make the Boy Scouts do it this way to improve their compass skills.

[+EScout]

In the Meridians, the North Reference setting gives you 4 choices: True, Magnetic, Mils True, Mils magnetic. The first two refer to degrees (360 of them in a circle.) The Mils refers to another type of compass, with 6400 points in a circle. Use Mils if you need more precise bearings and projections. One of my navigational multi-caches uses Mils True from 3 waypoints at the points of a triangle....

 

I keep my Meridian (used for back up now) on True (degrees) 99% of the time. My mechanical compass has a declination adjustment so it reads True north. I like to keep it all true north.