Marc Auslander wrote:
Just installed a new depth/speed system using the Raymarine ST60.

I think there was a note somewhere (can't find it) about separate
starting and house batteries because the Raymarine doesn't like
voltage dips! I just ignored that. No way I'm doing that on a 30
foot sailboat with a Yanmar 2GM that starts on no voltage at all.

Well - if I start when the battery is low - the Raymarine resets,
loosing all calibration. This includes the sea temp calibration which
is NOT set as an offset, but is set by measuring the actual temp and
then setting the display to that value! So you can't even write down
that calibration and reenter it.

For no, I have to remember to have the Raymarine off when I start
with low batteries!

I'm considering some sort of circuit using batteries or
ultracapacitors so buffer the supply voltage.

Comments? Any one tried it?
I have used a small (~12AH) battery, connected to the main battery
with a Scottky diode(80 amp), or a break relay.
The break relay was connected to the radio power, which is
switched off while starting, and so can feed the relay coil.
Your starting switch might have such a contact.
That way, starting the engine, or using an electric winch, does
not mess up your power.