I have an ST50 and an old B&G Hornet depth sounder in my boat and they don't
seem to interfere with each other. The transducers are less than 12 inches
apart. The B&G is just a backup that I would use in case the ST50 died.
Even if interference were occuring, in this case it would not be an issue.
Perhaps you are in the same position.

"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?