Another story I read indicated they had a map and were following a river or stream on the map. If I'm hiking in Denali, I'll have a map, compass, Gps, and PLB! Serious country up there!

I'm a big Geko fan ... I only wish it had the high sensitivity receiver so that I could be more sure that I'd get a fix in heavy forest cover.

Even moderate woods will cause my Geko 201 to loose the fix. My GPS 60CSX just laughs at such situations - even giving a strong fix in my basement!!

One thing to remember is that improper use of a magnetic compass (without properly adjusting for magnetic declination) can make a mess of following GPS goto waypoint bearings. Declination can be as much as 20-30 degrees in Alaska. In that case they'd be much better off simply following the GPS's compass tool - whether it has an electronic compass or not.

Of course a Personal Locator Beacon would have made VERY short work of their whole problem. I believe in PLB's. I bought one and carry it with me when out in remotish areas. And of course, even with a PLB one still has to be geared up to be found (signalling) and to survive long enough to get rescued (first aid, shelter, fire, water, ...).

Ken K.

I'm not a fan of using a GPS electronic compass (Geko 301) because they use a lot of battery. Much better IMO to watch the compass course as you are walking and use that as a virtual compass. Comparing that course with a mag compass should give you the correct declination to apply if you aren't sure.

IMO the strongest attribute of the Geko family is size; they're small enough to EDC (smaller than many cellphones) but they can give a precise location to a 911 operator if the situation requires.

I think Ken meant use the GPS to determine the bearing, then use the magnetic compass to follow that bearing.



-john

As a one time thing to determine declination, that can work too. While the GPS internal electronic compass is a magnetic compass, it has a declination table and allows you to select between true North and Magnetic North display. Easier would be to just look at what declination it is using when you select magnetic. It's easy to forget to turn the electronic compass off and then you lose battery life. Another nice thing though is that it's easy to carry a few spare AAA batteries.

Geez, it's been a while since I used that function, forgot a lot and had to turn it on and play with it a bit, going through all the menu options. It's good to be at least minimally familiar with your gear.

I'm glad that they were found alive.

Does it need the electronic compass to show bearing? Seems like it could just compute the bearing from one coordinate to another.

I suppose it depends on how they implemented it.

-john

I never really use a GPS for the calculation of bearings or azimuths, I only ever use the GPS just to record a positional fix directly associated with the OSGB grid paper map (regarded by myself as cheating, but is definitely useful when the occasional resection is impossible i.e. in a whiteout, fog or darkness and thickly wooded areas) as the navigational azimuths are done using just map and compass work only. The magnetic/grid/true north variance or declination is just calculated or noted prior to compensating for that variance with the azimuths being taken from the paper map directly. The same applies for any visual azimuths made using the compass when this azimuth is transferred to the paper map.

The Garmin Etrex provides a North reference in its firmware using the following types of variance from True North whereby Magnetic North is 5 degrees West and Grid North is 1 degrees West (for OSGB datum) for my current location. A User magnetic declination can also be entered. The GPS can then account for users who are navigating using a normal compass and not having to take into account the magnetic declination. The User of the GPS will of course still have to have an understanding of the difference between True, Magnetic and Grid North actually is. Not knowing that difference and how the GPS is setup in its firmware could cause some considerable error in navigation if a GPS and ordinary compass are used together in conjuction. For example the Etrex GPS might have been setup with a User magnetic/true north declination of say -180 degrees. The GPS may well be telling you to go North whilst your ordinary compass is pointing you South.

Does anyone know if the Etrex calculates the Magnetic/True/Grid North declinations from its own current position and time? The User manual doesn't say how it calculates the North References. This could be critical especially around the north and south magnetic polar regions for producing accurate azimuths from the GPS itself as the magnetic declination will shift rapidly with changes in position and time throughout the year.

Edit - I've just looked up the accuracy of the electronic compass built into the higher spec Garmin models. Accuracy is a stated +-5 degrees. So for many areas in the world relying on the electronic compass is just as pointless as not compensating for the Magnetic/True North declination in the first place.

i seem to recall recently reading, here i think, that when lost, contrary to widely-accepted belief, following a river downstream is not necessarily a good idea.

from the ap account:

" They brought a compass and a map but still lost their bearing, mistaking one river for another. They tried to follow the river, but that proved impossible many times, Flantz said. "

in my dayhikes, i've seen many stream dropoffs that would cause me to act like bear grylls, if lost and following a stream downstream. for me, no thanks.

just my $0.02.

If I got lost I'd be inclined to go to high ground first if only to maybe get my bearings.