Spotting Electrical Wiring Issues on Your Boat

Using a FLIR camera to look for hot spots on wiring.

Electrical wiring problems can be difficult to see.  They hide behind panels, corrode in bilges, and can spark fires if ignored. Salt air and vibration make it worse. The good news is you don’t need a full shop to catch them early. Grab a FLIR thermal camera and a multimeter. These tools turn guesswork into diagnostics.

You can start with the FLIR thermal camera. It’s like X-ray vision for heat. Scan your main distribution panel and wiring runs while the boat’s powered up under normal load—running lights, pumps, or charging. If there is no current on a circuit you will not find problems easily.  If you are using the FLIR to find a problem with a bad connection that generates heat you have to be using the device.  This may require you to raise and lower your anchor several times if you are trying to find a problem in the windlass circuit for example.  Look for hot spots: A glowing orange/red on a connection means resistance from corrosion or loose terminals. The team at Marine Craft has spotted arcing faults this way that multimeters miss.

Next, verify with a multimeter like this one from Marine Craft Supply. Set it to continuity or resistance (ohms) mode. Probe suspect spots from the FLIR scan—corroded terminals often show infinite resistance or erratic readings.  We often do a “wiggle test” when looking for problems with the wiring.  When your boat is sitting still there may be no issue.  However, when you start banging around the ocean the wires may move revealing the problem.  So grab the wires and move them around.  The terminals should stay in place.  There are ratings in the ABYC Standards for each wire size.  But all wires should maintain good contact with light pressure and moving the wires around. Switch to voltage drop test: With the circuit loaded, measure across connections (should be under 3% drop per ABYC E-11). If you suspsect a flaky ground check for 0.2 ohms or less to the battery negative. You must check the positive and negative of a DC system.  So many times we see problems on the negative side of the circuit. 

Once spotted, follow ABYC-recommended repairs for safe and reliable repairs. Clean corrosion with a non-residue contact cleaner, then re-terminate connections with heat-shrink tubing to seal against moisture.  Always install overcurrent protection at the source and label circuits. If it’s beyond DIY, our ABYC Certified technicians can assist you.
These tools and standards have saved us hours of tear-downs. At Marine Craft, we use these and other processes daily for ABYC certified world class workmanship. Spotting issues early keeps you having fun out on the water safely.
 
We’ll see you out on the water.

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Posted by Dave C., ABYC Master Technician 08 March 2026

Frequently Asked Questions

How can I find hidden electrical problems on my boat?

Use a FLIR thermal camera to scan for hot spots while the system is under load. Look for glowing orange or red areas on connections, which indicate resistance from corrosion or loose terminals. Then verify with a multimeter using voltage drop and continuity tests.

What is a voltage drop test and why does it matter?

A voltage drop test measures how much voltage is lost between the battery and the device under load. ABYC E-11 recommends no more than 3% drop on most circuits. Excessive drop usually means undersized wire, corrosion, or poor connections.

Why is the negative side of the circuit often the problem?

Many boat owners only check the positive side. Poor grounding or high resistance on the negative return path is a very common cause of voltage drop, flickering lights, and erratic electronics. Always test both positive and negative sides.

Can I use a residential multimeter on a boat?

Yes for basic testing, but a true RMS multimeter is better for accurate readings on marine systems. Make sure it’s rated for marine use and always follow ABYC safety practices when working with live circuits.

When should I call a professional for boat electrical work?

If you find hot spots, repeated breaker trips, burning smells, or voltage drops over 3%, it’s time to call an ABYC-certified technician. These issues can quickly become fire hazards or leave you stranded.

Why choose Marine Craft for electrical troubleshooting and upgrades?

Our ABYC Master Technicians use professional tools like FLIR cameras and follow strict ABYC standards for every repair and upgrade. We provide world-class workmanship with a focus on safety and long-term reliability. Call 252-571-9980 to schedule your inspection.