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On a boat, voltage is often king!!

On a home network, without salty air and abundant corrosion, we are powered by 240V or such like and a small 10% drop in voltage caused by corroded connections is a drop to 216V. BUT on a 12V boat a 10% drop caused by corrosion is a drop to 10.8v. This can cause all sorts of problems.

NMEA components work on a 12V powered backbone that is often not as well connected as it should be. Often the first thing to check when something is failing or not working reliably is the voltage it is getting.

The other day my Rudder angle indicator was reported missing in action, then I was getting confusing angle variations and things were getting exciting on autopilot as it tried to keep up with the changing mind of the device.

The truth was that a rudder angle indicator is a potentiometer device and highly dependent on regular and reliable voltage being delivered at the right level.

Sure enough, when I check , it was not getting full voltage at the back end of my NMEA backbone.

Hunting around found a corroded and slightly loose ground connection and within a blast with contact cleaner and a quick tighten the Rudder indicator was all reliable again. £480 saved on a new one!!!

I’ll write an article about tracing NMEA backbone voltage variations down. But for now, remember NMEA or something else… 12V boats are very susceptible to voltage drop.

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