I have both the Themi and Winpilot Pro. When I'm not flying my glider into
the ground, I find that both of these devices generally work as advertised.
They most often agree with each other too - - though not always. Also, in a
compound thermal with several lift cores adjacent to one another, they are
of no help in suggesting that the glider move to a stronger area in the
complex, as may be suggested by looking at the overhead cloud structure.

The Themi has one advantage over WPP, it remembers where thermals are for
the return trip. And if you arrive at a different altitude the second time
around, it accounts for that too. That said, if I already had WinPilot Pro,
I wouldn't spend the money on a Themi unless I needed that unit's logger
function.

bumper
wrote in message
oups.com...
At a fellow pilot's suggestion, for over a year I've been using Glide
Navigator II's "tracks" feature to help center difficult thermals. It
doesn't tell me where the best lift is but it does help me visualize
the thermal and see where I am compared with the previous circles.

More sophisticated soaring navigation software actually marks areas of
stronger lift and may even offer recommendations: e.g., WinPilot Pro,
SeeYou Mobile, and possibly others. I've stuck with GNII not only
because I like it but also because I'm still running it on the old
gray-scale Compaq 1550 and don't have one of the newer varios/flight
computers that add airspeed and variometer data to the GPS sentences
going into the PDA.

I'll ignore the very real concern about whether this feature tends to
make pilots look outside the cockpit even less than they already do. In
my experience, those who commit this sin are the same pilots who fly
their flight computers right into the ground when they accidentally set
the arrival height to minus 500 ft.

My question is do these features work well in WinPilot, etc.? Is the
relative rate-of-climb information accurate; i.e., is the best lift
displayed in the right place? What about the suggestions to shift the
circle in a certain direction (e.g., the Themi device)?

Chip Bearden
ASW 24 "JB"