If both sounders use the same frequency, which they probably will, then yes
they will interfere with each other.
A sounder works by measuring the time it takes for the signal to travel from
the transducer to the bottom and back. If two sounders are operating at the
same frequency they have no way of determining which signals return they are
receiving.


"Peter Hendra" wrote in message
...
I wish to install a 2nd depth sounder.

I have a Raytheon ST60 series sounder and a Navman 450 combo paddle-wheel
log
and depth. The Raytheon is already in use but I wish to install the Navman
depth
transducer as a backup and a check. It also will measure greater depths
than the
Raytheon which sometimes comes up with shallow depths in turbulent water -
when
the chart says 3,000 metres. I don't want to adjust its sensitivity.

Questions - Will there be interference to either or do both filter out
through
being different wave lengths or somesuch?

How far apart do they have to be?

What else haven't I thought of?