Bohli compass operation

On Sunday, August 30, 2015 at 12:06:10 PM UTC-4, Jonathan St. Cloud wrote:
Was wondering if anyone can describe their personal experiences with
a Bohli compass. Did you like it was it easy to use?

Eons ago I borrowed a glider that had a Bohli. I asked the owner
why the compass acted so oddly, and he said "oh yeah, it needs to be
sprayed with anti-static"!
Seems areas of the top plastic view-plate (with the markings) would
build up charge, and the little indicator ball would be attracted/repulsed
from the charged areas!

Made a really weird jumpy motion while thermalling - quite annoying.

Likely only a problem in dry climates, but it was really not usable...

No idea if they all have this issue or if the materials were improved.

See ya, Dave

I have about 500 hours flying a Nimbus 3 in South Africa with a Bohli. They are very nice devices and very accurate - they give virtually none of the turning or acceleration errors that other mechanical compasses have. To use it correctly you have to be fairly prompt to adjust the banking knob based on what you are doing. I found that after about the first 25 hours it got relegated to being a secondary or tertiary instrument as there is much more to be busy with (both in the panel and outside) on an XC flight than the compass. And while I understood the concept of cloud climbing & flying with one I never had the guts to do it with the usually ballasted Nimbus. The one I used was already installed and the installation (which requires a lot of cutting and shaping on the top of the panel) appears to take a lot of work and talent to do neatly. Bottom line: probably not worth the time, effort & expense to install one - but if you had one in place you would not take it out.

Roy