NW Topos - how to use

[weamish]

I've loaded and enabled NW Topos on the Garmin Montana. Suppose I want to hike the Comet Falls trail on Mt Rainier - can someone walk me thru how I'd access and use the maps and trail info? Thanks!

...Steve

[Seldom]

Can you be more specific?  What part of the Montana user manual are you having trouble with?

[weamish]

I've read the whole manual, particularly the navigation sections. I've used Garmin's automotive hardware for years, so I'm generally familiar with waypoints, routes, etc. But this is my first hiking GPS, and I don't see any obvious way to work with trails rather than roads.

Today I entered a waypoint at the trailhead, then used Where To > Waypoints to navigate back, but was informed that there were no routable roads. Even the compass didn't work for simple navigation back to the waypoint. Guess I must be missing something...

[maps4gps]

Is NW topos supposed to be routable?  Most free mapsets are not.

[Seldom]

Today I entered a waypoint at the trailhead, then used Where To > Waypoints to navigate back, but was informed that there were no routable roads. Even the compass didn't work for simple navigation back to the waypoint. Guess I must be missing something...

To get the compass to work you'll probably have to set your routing preferences to Navigate off road, or Direct.  I don't own a Montana, but those navigation preferences work for most of Garmin's handhelds.

You need to understand that Garmin's Automotive GPSrs com with routable maps.  Garmin's handhelds don't.  You need to buy them separately, or download from a free provider like garmin.openstreetmap.nl.

[weamish]

To get the compass to work you'll probably have to set your routing preferences to Navigate off road, or Direct.  I don't own a Montana, but those navigation preferences work for most of Garmin's handhelds.

Under Setup > Routing, I have Activity set to Hiking and Lock on Road set to No.  I don't see anything else in Setup that would affect the compass...

[weamish]

Is NW topos supposed to be routable?  Most free mapsets are not.

Is there any way to tell whether a mapset is routable, other than in the author's description? (I don't see any mention of this one way or the other)

[Seldom]

If you don't see any mention, it probably isn't.  AFAIK, only a few of my maps are.

[maps4gps]

If it does not state that it is routable, it likely is not.
There is a lot more work involved to make a mapset routable.
AFAIK, Seldom's is the only topo mapset on this website which is.  OSM maps are routable, but are not topo maps (no contour lines).

[weamish]

When hiking with NW Topos, the trail is clearly marked on the map. The icon wanders a bit, but is in general proximity to the trail. If this was a routable map, what would be gained? Would it be accurate enough to determine which of 3 or 4 branching trails is the correct one? Does it tell me to turn left or bear right or whatever?  Thanks!

Steve

[Seldom]

If you had a routable trail map, and had established a route from HERE to THERE (two waypoints or POI). The map would display a magenta line following the route, and would indicate Turn Left on SOMETRAIL, when you came to the intersection with SOMETRAIL.  But to do that you need to find a routable map with your trails on it.  If you can't find a routable map, the next best thing would be to draw a track in BaseCamp and TrackBack on that track. 

[Boyd]

If this was a routable map, what would be gained? Would it be accurate enough to determine which of 3 or 4 branching trails is the correct one?

That is a question of how accurately the trail is represented on the map. It has nothing to do with whether the trail is routable.

[weamish]

When using an automotive GPS, it often thinks I'm still on the highway after exiting onto a parallel service road. Or it thinks I've exited (because that's what the routing said to do) when I'm still on the highway.

So it's hard to imagine that a routable trail would tell me that I've accidentally "exited" onto a parallel trail. It could be miles before the new trail veered off enough for the GPS to distinguish the mistake. Is this what happens in practice?

...Steve

[Seldom]

It could be miles before the new trail veered off enough for the GPS to distinguish the mistake. Is this what happens in practice?

What are you using for a automotive GPSr?  GPS accuracy is generally around 30 feet without WAAS enabled but with a clear view of sky.  Maybe 15 feet with WAAS.   With limited sky view it can get way off (up to a mile), but that's not the fault of the map.  My experience is that when I'm about 100 feet up the wrong trail with a routable trail map any of my GPSrs starts to nag me to U-turn until I either acquiesce or continue far enough so that it finds a shorter way to my specified end point.

[Boyd]

On the Nuvi using City Navigator, your position is automatically "snapped" to the nearest road. So if a service road is right next to the highway the pointer could snap to the highway. This could be either because of an inaccurate fix from the satellites or a map error that puts the road in the wrong place.

But on Garmin's handheld units, you will find a menu option to enable/disable road-lock. If you are using routable trails, you may get better results by disabling it.