A few points that might be worth adding:

1) The application of MacCready theory optimizes your speed over a
cross-country course if you fly at the speed indicated for the expected rate
of climb

2) MacCready flight optimizes time at the expense of height. If you are low
or trying to clear a mountain ridge, it isn't appropriate to fly as fast as
indicated. If you slow down, you will lose less height (often even when in
sink). John Cochrane has given a good description of the trade-off betweeen
speed and height.

3) It probably doesn't pay to follow the guidance of an audio speed-to-fly
vario too aggressively - flying at a more constant speed may often be more
efficient.

and, most important......

4) My experience has shown that people grossly overestimate the achieved
climb rate on a cross-country flight. Here in Arizona, days with memorable
8 to 10 knot thermals rarely produce more than a 5-knot flight average and
2.5 to 4 knot days are more common. If you climb in a rare 10-knot
thermal on a day with a 4-knot average and set your MacCready setting to 10,
you'll be in trouble in a hurry! A good flight computer that will give you
the climb average for a flight will keep you honest!

Mike the Strike

ASW 20 WA

"JJ Sinclair" wrote in message
...
I fly a lot in the mountains and find MacCready speed-to-fly information,
completely worthless. Let me explain; Before crossing a ridge, I will fly
slower (below MC), so that I'm assured of making the next ridge. After
crossing
the ridge, I may fly faster than MacCready. If I set the proper MC setting
in
my computer. I am constantly bombarded with WRONG information coming from
the
computer audio.

For the last few flights, I have tried something new. I turned OFF the
computer
audio (B-100) and turned on the back-up vario (B-40), Now I have audio
only
when going UP and nothing when going down. I locked the computer in cruse
mode
and if I need to know what MacCready thinks about the speed I should be
flying,
all I have to do is look at the speed-to-fly needle.

One more tid-bit, I had radio interference (breaking squelch) when I
installed
the B-100 in my Genesis. I found that the cable to the LCD display was
real
sensitive to triggering the interference. When I would bring the radio
antenna
cable close to the LCD cable, It would break squelch. I completely solved
the
problem by keeping these two cables 6 inches apart. I also found the NMEA
cable
from the Cambridge GPS would trigger the radio squelch, if it was closer
than
6 inches to the LCD cable.
Cheers,
JJ Sinclair