Trolling Motor: Marine Grade Wires

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“Why are my copper wires silver?” or “Are your wires made with copper? Then why are they silver colored?” are questions we get all too often. The quick answer is yes, all of our wires are made from pure copper. However, tin is added to the wires to make them marine grade. Below we will discuss why pure copper wires aren’t used in marine environment and why tin is applied.


Pure copper is a highly prized industrial metal due to its malleability, its ability to transmit electricity and heat, and its resistance to corrosion. It will always be the industry standard for creating wiring for these reasons. While copper it is able to resist corrosion fairly well, it can still oxidize and lose its electrical conductivity over time. Oxidation is a slow chemical reaction that occurs when copper is exposed to air. However, this process can speed up when it is exposed to high humidity and moisture; essentially a marine environment. This is why marine grade copper should be sought after over pure copper in a marine environment.


Oxidation is the chemical reaction of a substance transferring electrons with an ion, atom or molecule. When copper is exposed to the surrounding air, it reacts with oxygen and loses electrons. This process is accelerated in humid environments due to the increased water in the air, which can also oxidize the copper. You can see this reaction occurring when copper begins to turn a green or blue color; a well-known example of copper oxidation is the Statue of Liberty. This green/blue outer layer is called copper oxide and actually forms a protective layer around the rest of the copper preventing further corrosion. However, while it protects the copper from further corrosion, it decreases its electrical conductivity. This is not ideal for those who are looking for top performance from their trolling motor day in and out.


Tin is an extremely soft and pliable metal that has a variety of uses from soldering to coating other metals to prevent corrosion. Tin is used with copper due to its resistance to oxidation and water corrosion. It oxidizes at a much slower rate and is extremely compatible with copper. Tin is also used, as opposed to another metal, to reduce the chance of Galvanic Corrosion occurring. This is an electrochemical reaction in which one metal corrodes preferentially to another during electrical contact, in the presence of an electrolyte. This process could occur in your trolling motor as it is constantly used in water (an electrolyte) with electricity running through the motor. Tin is, therefore, one of the best choices for coating and protecting copper wiring.


Pure copper is great for electrical conductivity but can oxidize quickly in a marine environment and decrease its performance. The marine industry has addressed this issue by coating copper wires in tin. This forms a protective barrier that resists corrosion and keeps your wires conducting electricity properly. The silver colored wiring you see in your trolling motor is not an attempt to save money and give you a lower quality product, it’s there to enhance the performance and improve the longevity of the motor. Newport Vessels doesn’t cut corners, but rather strives to continually manufacture and produce quality products that last.

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