Electronics failure - Raymarine instruments

[Kefalonia]

Hi, I'm new to this forum, though have had some great advice from reading previous threads.

I have a Bavaria 42 cruiser that we have for charter in Kefalonia. On the last trip the boat suddenly veered to one side whilst on autohelm. When I went to see what the cause was I saw that a number of things were wrong. I'm not sure if some or all are linked but here they are:
The instruments are Raymarine ST60 Tridata.

1. The electronic compass on the autohelm was swinging randomly between 30 degrees and 200.
2. The speed and log stopped working.
3. The battery alarm was sounding intermittantly all the was back to port.

I did some investigating when we were in port, and found that the prop on the speed meter was clogged with seaweed and various marine life. I cleared this and the speed was registering when i spun it. However, when I put it back in and sea tested it, it didn't work.

Any suggestions to any of the problems would be much appreciated

Paul

[chala]

I would disconnect the Seatalk bus from each instrument and test them independently. In a chain I would check first the one the closest to the supply if it work then I would ad another one and so on. If does not work, try another instrument if it also does not work I would pay attention to the supply for dip in voltage, dip that may be caused intermittently by an appliance or a bad connection.