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What Is Marine Battery Wire? And, Why It Matters

29th Sep 2020

At EWCS Wire, we specialize in providing our customers with electrical wires and cables for all of their needs, and if there’s something we’re good at in addition to doing that, it’s shedding some light on some esoteric topics.

Take a look at some of our recent blogs, in which we exposed and explained some of the terminology of our wiring, and gave an in depth explanation of what exactly is meant by a product listing that says “10 AWG Solar PV Multi Conductor Tray Cable.”

We sell a lot of specialty wires and cables here, like welding cable, tray cable and armored cable in addition to our many varieties of relatively simply building wire and cable, and if you don’t know what you’re looking for, it will get confusing in short order.

This is only exacerbated by the fact that you might be a boater looking for electrical information, and not an electrician or an electrical engineer. Come to think of it, that makes sense because if you already knew what marine battery wire was, you probably wouldn’t be looking for information on it.

However, boaters have a need for it, and using regular electrical wires and cables on a boat is going to set you up for problems down the line. Therefore, we’d like to get into some of the specifics of what marine battery wire is, how it is made, why it is necessary, and what differentiates it from other wires and cables, including those you will find on our website.

First, however, we’re going to take a step back and look at conductors in general, as well as why they are used and how.

Wires Keep the Lights on!

It’s important to keep in mind that many wires and cables are specialized to their duties, and that the world runs on power. In fact, some highly regarded development indices of standards of living are tied to how much access a given location has to electrical power, among other, more obvious things like clean water and healthcare. Wherever there is electricity, there must be conductors, and most of the conductors used in the world are cables and wires.

We’ve belabored this point many times over in past blog entries, so we won’t beat a dead horse on the matter at hand. A wire is a single stranded conductor and a cable is simply a braided arrangement of smaller conductors. That answers the difference between wire and cable, but not what a conductor is.

A conductor is simply a material that carries an electrical current; or, to make the matter more approachable, conducts it. Most conductors are made of metals like copper, gold or aluminum for a few reasons. The different metals will vary in why they are chosen as conductors, but for the most part, they will offer some arrangement of the following advantages.

The first thing a conductor must offer is a high rate of conductivity, which is tied to a low rate of resistance. Resistance, which is measured in Ohms, is the amount of force that is required to “push” electrons through a medium. If a material has a high resistance, it will create a lot of heat when a current is forced through it, which can be very dangerous. Conversely, materials with relatively low resistance like copper, gold and aluminum, allow electrical currents to flow through them nearly unimpeded.

Conductors are also chosen for a number of other factors, such as their resistance to corrosion, their malleability, their ductility, and their weight, although cost is also a factor. Consider that a gold has very low resistance and is also highly malleable and ductile, but it is extremely heavy and even more extremely expensive; interestingly, gold is also not reactive so gold wiring is not prone to corrosion. For this reason gold circuitry is reserved for highly specialized uses. Copper, which has low resistance, is malleable and ductile, is lighter than gold and more affordable. Unfortunately, it is reactive, which is going to matter when we get into the specifics of marine battery wire.

Features like these make a wire or cable fitting - or not fitting - for an environment, and wherever there is power, there must be power lines. To use the expressions, wires and cables “keep the lights on” but they do much more than this, especially on boats.

Boats Need More than Lighting!

Boats, like other vehicles and components of infrastructure, need power, and not just for their lighting. Their lighting is critical, however, and a matter of legal obligation as well. Motorized watercraft are variously regulated by local, state and federal laws, and among other things, are required to have operational navigation lights and all-around white beacons when they are under power in darkness or adverse weather conditions.

But it goes much further than this, because some ships and boats rely on their navigational systems in order to get to and from where they are going. Ships use radar to navigate tricky passages, and a ship’s wireless radio is its lifeline; in fact, they have been since they were introduced over a 100 years ago. Without power, all of these things go dark, and a boat without power is dead in the water, literally. Boats and ships also rely heavily on the safeguards of their pump systems which keep them from taking on water in rough weather and heavy seas.

Even if these things didn’t matter (and they do) any boat with an engine needs an electrical system not only to start it but to cool it and operate it. Again, without electricity, there is no progress in the water and no way to operate a motorboat. In short, without an electrical system, a boat is crippled, and that is where marine battery wire comes into the picture.

When the Waters Are not so Placid

There are a few key factors that make marine battery wire well suited to its situation, and one of them is the fact that boats are in constant motion, even when they aren’t under power. Consider that a sailboat may have no engines, but it most certainly would still be in motion. In fact, it would be in motion even when it was moored, because the tides are constantly rising and falling.

This is an extreme example, and a better one would simply be to point out that boats under power are constantly navigating waves, swells, tides and currents, even when these are not too powerful. Even a weak swell puts a lot of stress on a boat, and when the boat moves, so do everything inside of it, including the wiring.

Therefore, marine battery wire and cables are designed to be able to handle this constant stress and motion, even if it is minor most of the time. Single stranded conductors can be bent, but they are relatively inflexible in the grand scheme of things, and therefore marine cables are made up of a very high count of very finely stranded conductors, much more than normal.

These extra conductors enable these cables to put up with the stress of the body of a boat or ship that is even in motion, even if it is subtle. Something else to note here is that the high strand count makes these items cables, categorically, so calling them wire is a misnomer of sorts. Either way, the high strand count engenders an uncommon degree of flexibility that is valuable for holding fast when the conditions are less than agreeable.

The Engines Are Constantly Humming

The waters are not all that are in motion when a motorized boat or ship leaves port. Everything else on the ship is constantly moving too, not only the engine, although that is the greatest source of vibration most of the time.

Consider that a ship or boat could be under way for days at a time, which means the engines would be constantly running. That sends its influence throughout every corner of the ship, and when something doesn’t bend, as the saying goes, it must therefore be inclined to break. That is one more reason that marine battery cables are designed to be so flexible; they can rock with the boat and absorb some of the vibration from the engines.

However, other electrical components of a ship or boat are equally influential in lending noise, vibration and stress. For example, whenever the pumps are running, they will send vibration throughout the structure of a ship as well.

There’s still one more thing that requires the wiring in a boat to be highly flexible, but it doesn’t have to do with the movement of the ship itself. Rather, it has to do with the express lack of space on a ship, or a boat for that matter. If you have ever been inside one, which is likely if you are reading this article, then you will know that space comes at an extreme premium. Because of this, boat wiring and cables that are worked throughout the hull and to and from the battery must be able to bend around tight corners and fit into even tighter spaces. The high degree of flexibility exhibited by marine grade battery cable makes this possible.

The Waters Are Corrosive

One more thing makes these types of cables valuable for a life on the water, and that has to do with how they are treated. If you take a look at some of the marine cables that you can find here on our site, you might be tempted to make the assumption that they were aluminum cables, but they are not. This is due to the simple fact that they appear silvery.

This ‘silver’ color is not an attribute of aluminum composition, but it is attributable to the composition of the cables. This is because seawater, like many conductors, is reactive. Typically, we would use the term corrosive, but either of them is fitting.

When seawater comes in contact with reactive metals like iron or copper (which makes up a lot of the electrical conductors in the world, marine wire included), it wreaks havoc. Surely you are familiar with the sight of rusted metal by the shore or of copper that has turned a bright patina because it has been exposed to salt water or just a salt spray. Seawater makes quick work of reactive metals like copper, which is no good if you need that native copper to remain conductive.

To fight this, marine cables like the high quality cables right here at EWCS Wire have a trick up their sleeves, and it’s the same thing that makes them look silver. To combat the effects of corrosion that would be caused by exposure to seawater, finely copper stranded conductors are individually tin plated. This tinned copper stands up much better to saltwater than naked copper would, and it suits these types of cables for life at sea, at least much better than they would fare otherwise.

What We Provide

There you can see, in a nutshell, just what it is that makes marine battery cables well suited to the situations in which they will find themselves, namely, being on a boat at sea. As the Electrical Wire & Cable Specialists, we know a thing or two about what makes quality marine cables, and that’s why we offer these in our online store, in addition to the categories of wire mentioned above, and many others.

If you have more questions about marine grade cables, or you just want to learn about some of the interesting products we make and sell, then get in touch with our team. You may be able to catch us via the live chat feature at the bottom of our website, but if you miss us you can give us a call or send us an email. Give us a call - we’d be glad to hear from you - at 800-262-1598, or you can email us at sales@ewcswire.com. We love to hear from our customers and we’d love even more to talk about our specialty products with you!