I think it's admirable when people are able to keep old gear
like this running. Not to keep throwing away perfectly good stuff and constantly buy new stuff.
But where GPSs are concerned -- there have been great leaps in the technology since the Raystar 120's and 125's were designed.
these days are much faster, much more sensitive, receive other systems (GLONASS, Galileo), have WAAS which works in Europe
too (EGNOS), give more precise position data. And -- on top of all of that, have become much cheaper.
This is one type of gear
where it really might make sense to toss the old stuff. A new Simrad
GS25 costs less than $200 and is great leaps ahead of previous generations of GNSS receivers.
The other thing worth tossing is old style fluxgate
compasses. The new generation are based on solid state magnetometers and are much more stable, and most of them are now gyro stabilized.