This problem was solved by doing a full software reset and
recalibration. It works fine now.


At low wind speeds, my Navman 3100 wind display is erratic. It reads
true for a few minutes, then for a few minutes it reads garbage. It
tends to cycle between these two modes. At above ~10kts apparent, it
seems to work fine all the time.

The masthead wand (anemometer) and instrument are new replacements.
The only thing that I haven't replaced is the mast wiring, which is
new as of 2005.

What would cause such odd behavior? What is the protocol between the
masthead and the instrument? Is it NavBus? What are the electrical
properties? Is this an analog circuit? Could there be some sort of
grounding issue? If there is an intermittent connection on the wire,
why would it phase in and out while at the dock and not moving, but
then be fine and steady underway?

Any suggestions or ideas would be appreciated.

-JK

wrote in news:b15daec4-b3e3-44a4-9ae8-72661ab33cc0
@d42g2000prb.googlegroups.com:

This problem was solved by doing a full software reset and
recalibration. It works fine now.



If the problem recurs, listen carefully to your 12V boat stereo while the
alternator is running and when the charger is running. Listen for a
whining noise from the alternator that varies pitch with engine speed. The
alternator will be a low level constant 120 Hz bass note and is harder to
hear.

These noises indicate corroded 12V connections or dead cells in the
batteries, causing series resistance to the charging. It causes any
charging or loading to have an AC component riding on top of the battery DC
voltage. If it gets bad enough, this pulsing (from heavy loads coming on
and off) and whine from the charging, will cause computers hooked to the DC
like your wind computer to scramble its data.

Lightning pulsing the wiring to the wind head from last summer's storms
also causes the computer to become scrambled, without destroying
it...sometimes. It's called EMP (Electromagnetic Pulse) and will render
the whole country electronically dead when the nuclear weapons go off.

If you see the DC lights blinking when a fridge or bilge pump comes on,
that's an indication of the series resistance in the DC battery circuits.