After more than 40 years in the marine industry, I’ve had the opportunity to work on and inspect a lot of boats. In the area of electrical installations, where I’ve spent most of my time, I’ve seen plenty of common mistakes, made either at the factory level or by aftermarket installers. Remembering that the most common cause of onboard fires is a fault in the electrical system, it’s worth a look at what some of these faults are, and how they can arise.

Yellow arrows point to areas of concern in this battery installation: uncovered terminals and fuses that may be substandard.

Yellow arrows point to areas of concern in this battery installation: uncovered terminals and fuses that may be substandard.


Battery Installations


Without a doubt, the most common area where I see foolish mistakes being made is in the installation of batteries—both engine-starting batteries and those used to service house loads. This problem seems to have gotten worse in recent years with the proliferation of what I’ll refer to as “new age” battery technologies. The reason for this is two-fold. First, modern batteries are most likely to be of the sealed variety, regardless of specific technology. Second, current densities are often considerably higher than in conventional flooded lead-acid batteries. For a look at some of the specific issues, read the following:

Bad Connections


No, I don’t mean having no bars on your cell phone—I’m talking about bad wiring connections. In classes I’ve taught all over the world to marine electricians, I emphasize that the most common fault with electrical circuits on board boats is not the short circuit, as is often believed. Without a doubt the most common fault is what we call the “unwanted open.” What is meant by this is a circuit where electrical current flow is interrupted by the creation of an “open” in the electrical flow of things. In plain English, something has come unplugged. This can be caused by a faulty crimp connection or a friction connector that simply unplugs itself. More often than not, the root cause of these issues is poor-quality workmanship. To learn some of the ways to avoid these mistakes check out these Q & A posts:

Inverter Installations


In the last 20 years, inverter installations have become quite popular. They give boaters the ability to convert DC battery power to AC power and run things like TVs, microwaves, and blenders, and to recharge the myriad of electronic devices that many consider absolute necessities. The problem is, many of the inverter installations on boats are not done in accordance with important safety standards. Check out the post to learn more on this topic:

The fuse on the right complies with stringent European regulations, but might raise an alarm with an American surveyor.

The fuse on the right complies with stringent European regulations, but might raise an alarm with an American surveyor.


European vs. US Shore Power Installations


Americans interested in buying new sailboats today soon realize that many of their choices will be coming from outside of the US. One of the problems I see regularly as I inspect new boats is shore power wiring that is undersized. You see, in most of the world AC power is running at 220-240 volts, as compared to the 120 volts common here in North America. Unless the builder both knows that a boat is going to be delivered in North America, and is conscientious about it, there’s a strong possibility that the wiring for the shorepower system is going to be approximately 50% smaller in gauge size than it should be to ensure maximum safety and performance. Additionally, things like plugs and receptacles may be in the European configuration. Check out this post to learn more:

Lithium Battery Installation and Safety


Over the last several years I’ve seen an increasing number of lithium-ion battery installations on new boats and boats attempting to convert to this technology. I’ve also seen an alarming number of fundamental mistakes made relative to these installations. One of the primary errors is in the area of fire-fighting/suppression. It is imperative that everyone understand that a thermal runaway situation with LION batteries cannot be extinguished with any conventional extinguishing agent, although water can help mitigate it. Now, this is counter-intuitive because conventional wisdom tells us never to use water to extinguish an electrical fire. But a LION fire is a chemical fire, not really an electrical fire. And even though water can help cool it down, the fire will not stop burning until all of the “fuel” within the battery is consumed. Check out this post to learn more:

The terminal shown center-left is so overloaded that the nut threads are half-exposed.

The terminal shown center-left is so overloaded that the nut threads are half-exposed.


Older Boat Compliance with Current Standards


One of the problems I run into with older boats, or more accurately with surveyors evaluating older boats, is how to assess a boat’s level of compliance with today’s safety standards. It’s important to understand that safety standards evolve. But the question becomes: Should I attempt to update everything on my 15-year old boat to current standards? The answer is maybe not. Check out this link to see why:

Electronics Blinking Out


One of the most common complaints I hear from boat owners is that their electronics blink out when they start the engine, especially after they have been sitting at anchor or drifting for an extended period with electric or electronic gear running. The problem is usually due to a low voltage spike in their electrical system. To learn more, go to this post:

The nylon tie-wraps holding hoses on top of this Yanmar diesel won’t last long in the heat of the engine compartment.

The nylon tie-wraps holding hoses on top of this Yanmar diesel won’t last long in the heat of the engine compartment.


Nylon Tie Wraps in the Engine Room


A common problem I see all the time is the use of nylon tie-wraps in places where they are likely to fail in short order. In some cases, this can mean wiring ending up in places it shouldn’t be, causing a dangerous situation. See what I mean in this post:

Bow Thruster Batteries Losing Their Charge


Bow thrusters have certainly come of age. Many new boaters believe they really need this expensive accessory to make their docking easier. Fair enough, but from an installation perspective these installations can be problematic. One of the problems is getting power to the thruster motor, which draws a considerable amount of electrical current — on the order of several hundred amps. To learn more about it, read this:

Brass vs. Copper as a Conductor


One of the things I see all too often when I’m inspecting boats is the use of brass buss bars in the power distribution systems. Even though I am quite aware that this has been done for decades, I still can’t warm up to the idea. Get a look at this post to see why:

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