Training Log Archive: BillD

To kill time while S at Watercolor Group, I walked the blue and yellow trails at the Mary Edwards property of the Granby Land Trust. Very nice woods and the middle part of the yellow trail loop goes along an exciting ravine. The main feature of the preserve is at the summit of the mountain -- Mary's Rock with a view to the n.e. of Springfield.



I am wondering whether the preserve might lend itself to orienteering. The woods are largely open but there are some laurel patches. Kind of a conical mountain and a long climb from the side road or the ravine. The mountain seems to have smooth slopes with few reentrants. I did not see many distinguishing features from the trail, like boulders (yes, there are some) or cliffs. I didn't have time to cross the ravine and explore the Blue Trail Extension. The trail map indicates there is a lot of land beyond where that Extension extends. Maybe there is some LIDAR available to assess the topography?

C • Mary’s Rock 2

A walk-jog around the Sessions Woods road. Odd laps walking, even laps jogging. I believe this was my personal best for this course. Nice dry, cool (48F) day.

On a hike through Stratton Brook State Park, I recorded a GPS track on each of my iPhone (GPS Tracks app) and my Garmin 310XT watch. The former was set for medium resolution, the latter for smoothing according to changes in direction or speed. See a graphic comparison on Google Maps.

The tracks are substantially similar, but the iPhone suggests more zigs and zags, even on stretches of the hike that were straight.

The iPhone reported a distance of 3.71 km while the Garmin reported 3.47 km.

While I started and stopped both devices within about 10 seconds of each other, the Garmin reported an elapsed time that was 48 seconds faster (42:18). That suggests I should try an independent stopwatch comparison, perhaps when standing still.

A comparison of track points from the respective GPX files recorded at the same instant in time shows disparities in Latitude and Longitude begin in the fifth or sixth significant digit. The iPhone recorded to 14 decimal places while Garmin recorded to 25 decimal places.

The iPhone app was marking points every 2 to 12 seconds, while the Garmin was marking points every 2 to 6 seconds.

So what? One conclusion might be that someone not wishing to pay for a Garmin but who has an iPhone can get a reasonable GPX file from the iPhone. But the iPhone is less convenient for runners, does not smooth the track well, and overstates the distance compared to a Garmin. Maybe there is a better app than GPS Tracks but I haven't found it yet. Such an app might even tie in with the Apple Watch for convenience in Start/Stop/Lap marking.