earthing

[jaycee]

my boat of nearly 2 years has 2 or 3 problems. when bought all electrics worked however the depth, gas detector and radio are all tempremental. i seem to remember that there was an electrical wire connected to the propshaft at one end and somewhere at the other end. during autumn 2003 the wire appeared to have been broken. i do'nt know if this is coincendetal or should i be looking somewere else. thank you.

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[john_morris_uk]

You appear to have two problems.

The wire from the propshaft was almost certainly part of the cathodic protection of the boat. You should check where your hull/shaft anode is and see that there is an electrical connection between the parts that need protecting (p-bracket prop etc) and the anode. The connection should be of a low resistance (a few ohms on a multi meter).

For all the instruments to fail/become intermittent sounds a bit of a co-incidence and possibly/probably unconnected with the above. Check the supplies to them. Is the battery failing/has a faulty cell giving you low voltage. Check all the wiring and hopefully you will find the fault. I'd start by checking the batter voltage and then follow it through to each instrument.

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