Why Corrosion is Such a Problem in Marine Engines and How to Fix It
Corrosion is the bane of every saltwater boaters existence. It can still happen to all the freshwater boaters too, but it just happens so much faster and more around saltwater. It is one of the biggest issues with electrical equipment and connections. It can cause some items to stop working temporarily, and in some cases permanently. It is pretty much impossible to stop entirely, but there are ways to prevent and reduce corrosion. In this post we will go over what corrosion is, how it happens, what causes it, and how to prevent it.
What is Corrosion and Why Does it Happen?
There are several types of corrosion, but what we are talking about is galvanic corrosion. This is caused by two dissimilar metals having a chemical reaction in an electrolyte solution. That means when two metals, especially a conducive one like copper, come in contact with aluminum, iron, or steel, the copper will start to corrode in the presence of water, especially saltwater. It is required that marine electrical wiring be done with copper wiring, because it is the best and safest for the job in spite of its tendency to corrode. Conductive metals will corrode more rapidly than less conductive metals. This principle is what makes sacrificial anodes, or “zync” anodes effective against the lower units of the engine from corroding. Zync is more reactive than the aluminum body of the lower unit. The zync gets sacrificed to the galvanic corrosion and the aluminum lasts longer. If these zync anodes are not replaced or maintained the aluminum will corrode and get ‘eaten away’ by the saltwater. Copper wires don’t have the benefit of sacrificial metals, so we simply need to be aware of the risks of corrosion.
What makes corrosion damage marine equipment?
The process of corrosion is a process that results in the wire deteriorating. The deterioration creates higher resistance, which once it gets to a great enough point will stop components from working. It should be noted that this type of corrosion can occur in both wires and within devices themselves. Wires can be changed fairly easily, wiring within a device is harder to fix. Corrosion inside a component usually means the device needs to be replaced.
Preventing Corrosion
On a boat corrosion is inevitable. That doesn’t mean we can’t prevent it, or at least reduce the extremity of it. The best way to reduce corrosion is to prevent saltwater, or any water, from coming in contact with any electrical connections. This can be accomplished by using proper connection coverings, like on a fuse box. The best way to prevent water from coming in contact with electrical connections is to cover the connections in dielectric grease. This prevents saltwater, or salt air from contacting the electrical connections. It won’t stop corrosion permanently, but it does reduce the severity and prolong how long it takes for corrosion to start. Making proper connections to terminals helps keep wires from corroding. Reducing the amount of exposed metal also helps reduce corrosion. Soldering connections makes a more secure and waterproof space that prevents saltwater from contacting the metal. Preventing water coming in contact with copper wiring is critical to preventing corrosion.
Common Mistakes People Make
One of the biggest mistakes people make that allow corrosion to occur is not putting the cover over their fuse box. People look the these covers an see how little they cover and think they are not important. They are extremely valuable for keeping moisture away from all of your electrical terminals. Another major mistake people make is attempting to diagnose their own electrical systems. The diagnosis is not the problem. A problem in the process is the problem. People will use a probe to pierce the insulation of a wire to test voltage. NEVER do this! While it can be an effective way to test part of an electrical circuit it only tests up to that point, and is guaranteed corrosion throughout that wire in the near future. So testing that way is just creating problems in the future. Simply test your circuits at terminals. If you think the wire itself is the problem test continuity or resistance at either end. Voltage is ultimately what is important for if a component will work, but continuity and resistance can be valuable measures for determining where a problem is.
