A note on isolation

Why I'm paranoid about the service power and computer ciruits

Keeping the Raspberry Pi isolated from the high power 12 or 24 volt system on the boat is more important than many of us think. Few of us would like the 230AC mains into the computer system, but the 12/24 low voltage system has on many yachts quite a similar power. Just imagine the power of a windlass or winch, 1kW or even more. It is the power that can cause overheating, burned boards, cables and even fire. Fire is, after being run over by a big ship, the second most dangerous event to be afraid of on a yacht. The old phrase "with great power comes great responsibilities" apply just as well to electricity that to politics or management. We all read stories from time to time about unlucky souls who fried their Raspberry, if you're really unlucky you might trigger a fire onboard. 

No to mention all electric noise and surges that can appear on the power lines when things like a windlass or other electric motors start and stop, a there is a lot of nasty spikes etc on the yacht's power lines. While these are also transmitted av electromagnetic waves they travel far better in cables. 

Hence it pays of to isolate the sensitive Raspberry Pi and it's sensors from the rest of the yacht. Isolate the power supply  using Buck converters that introduce a galvanic isolation between its source and outputs. Use isolation converters from NMEA 183 and NMEA/CAN bus and the computer system.  

One simple option would be to run all electronics from an isolated 12 V power supply. Normally there are separate fuses and circuits for the electronics and one might insert a buck power converter to isolate the service power from the electronics supply. We have all seen 220 VAC outlets in offices marked data or computer, almost the same. Some problems arise when dealing with SSB radio and such where the consumption is in the order of 50 A as 12V.

After some thoughts I have adapted an internet of things approach (see the separate page about this for more). This approach will solve many of the isolation problems as a large fraction of signal cables will be eliminated. Most of the sensors can be connected to a ESP8266 or ESP32 and the SignalK message sent over wifi. 

All of my projects related to the yacht server are isolated as god as available technology can do, within reasonable cost.

The buck converters are nice, but they do provide high frequency electric noise on the 12V side, so putting on some chockes is a good idea.
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