Protecting Onboard Electronics

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Protecting Onboard Electronics

by Rick Medero s/v C_Language

Protecting Onboard Electronics

Have you heard of or experienced this: "I re-commissioned my boat and found my radar doesn't work". The cause could be one of the most common insults to marine electronics: lightning, corrosion and electrolysis. Here are some tips on how to improve the odds your equipment will survive.

While lightning damage seems that it would be obvious, often is not. Semiconductors, (many of the little bits in our gadgets), are really good at manipulating small currents and voltages, but most are very susceptible to excess voltage or current, even for extremely small durations. A lightning strike does not have to hit your boat for some of these parts to get zapped. A near strike can create a high magnetic and electrostatic pulses especially in equipment with a large electrical footprint. What I mean by footprint is how many wires the device has connected and where they go. Handheld devices are least likely to suffer damage, while devices with connectors and long wires that act like antennas collecting the pulse energy are most likely to get zapped. Lots of words but no tips yet, so here's the tip:

Disconnect as many connectors as practical when the device is not going to be used for a while or when lightning in the area is likely.
Note: Disconnected connectors are more susceptible to moisture so take care to protect the exposed connectors. Don’t wait until the storm is on top of you as it is not wise to be touching the connectors when lightning is near.

Corrosion and electrolysis are usually greatly accelerated when a DC voltage is applied. Any equipment that will not be used for a while should not have power applied. This is true for electronics as well as electrical equipment like windlass and engines.

Some time ago I fixed my friend's GPS where the power button contacts had completely been eroded by electrolysis. He seldom tuned it on but always had power to it. The point here is, turning a device off may not make damage less likely, but removing the power does.

It is these compounds as well as other biological matter that cause the blockage of fuel filters on yachts and commercial vessels. I've seen it happen on new ships where we walked the tanks in the yard and found them clean enough to eat off of. Then pumped aboard 70k barrels (3.78 million gallons) of #2 diesel of clean filtered fuel. A couple days out in rough weather started plugging fuel filters and losing the plant for no apparent reason. You'd look in the centrifuges and there was voluminous amounts of black sludge. Some of it being so fine that it would get through the centrifuges and plug the 30 micron primaries solid.

Installation tips:
  • Mount equipment in a manner that makes it easy to disconnect and reconnect cables.

  • For devices that don't have convenient connectors, consider adding in-line connectors. I have done this on the antenna connection to my SSB tuner.

  • Protect connectors and equipment from moisture.

  • Power to equipment should have switch/breaker near the power source.

  • Use dielectric grease on connectors to displace moisture and oxygen.

For the more electrically inclined folks:
A relatively new device is available commonly referred to as a Transorb. They are specialized Zener diodes designed to suppress voltage transients. While manufactures take some measures to protect device inputs and outputs I am often surprised how little is done. Transorbs can be added to inputs and outputs using DC ground as the transient sink.
They are available in unipolar and bipolar and in a variety of voltages.

Rick's site s/v C_Language


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