Corrosion and Marine Electronics: Choose an IP67or IP68 Rated Fixture for Resistance|
Incandescent light fixtures don’t typically last long in a marine environment. The salt water, constant exposure to salt spray and moisture, the way electricity tends to aggravate the corrosion process and the general intensity of the environment out on the open water all tends to make short work of electrical equipment. It’s a simple fact; except for platinum, gold and palladium, metal is going to corrode. Under normal conditions, however, the corrosion process can be all but stopped indefinitely with fairly little effort. The problem in a marine environment is that the process is severely accelerated by the constant presence of water and salt.
While most boaters are well aware of how serious the problem of corrosion is, most only know enough to adhere to the most basic preventative measures to combat it. For instance, most boaters know quite well the importance of washing down their boat with fresh water once it’s been removed from the water, but could not explain the basics of uniform corrosion if asked. This is ironic considering that uniform corrosion is one of the processes most responsible for the damage done to prone materials when they are left exposed to the chlorides in salt water, which is the reason for the importance of cleaning after exposure. There are several types of corrosion, but for our purposes here we’ll only concentrate on one, Galvanic Corrosion.
With electrical equipment, the problem of corrosion is exacerbated. Galvanic Corrosion in this instance is the offending culprit and when dissimilar metals and electrical current mix, galvanic corrosion is the natural result. Galvanic corrosion, put simply, is the electrical process that takes place when two dissimilar metals are placed within an electrolyte, in this case seawater. When two metals, say steel and aluminum, come in contact with each other and are exposed to an electrolyte, an electrical current is produced. Water is a good electrical conductor and therefore an effective electrolyte and salt water even better, so the production and flow of current and thus the process of corrosion, is much greater in salt water environments. Different metals have different properties and what matters most here is the chemical stability of the metals in question.
The more “stable” a metal, the more resistant it is to the process of corrosion. For example, stainless steel is chemically more stable than aluminum. If you look at the aluminum lower drive unit on a boat equipped with a stainless steel prop and no corrosion protection, you would see the aluminum corroding more quickly than the stainless steel. This is because electrons are more readily released from the less stable metal and will tend to flow towards the more stable metal, where they then disperse into the electrolyte. As this happens, the aluminum loses atoms which become ions, which then bind with the oxygen atoms in the electrolyte, or salt water in this case and form aluminum oxide. The aluminum is thus literally dissolving into another form, which results in the powdery aluminum oxide coating and pitting often seen on aluminum in marine environments.
With electronics, galvanic corrosion can be a particularly serious problem as you have probably already surmised. Circuitry and the materials used to form electronic pathways and the materials used to form housings and heat sinks are made up of several different metals, which obviously introduces the potential for a great deal of galvanic corrosion to take place. Normally electronics experience little problem as long as they are kept dry. In marine environments, however, both the spray of salt water and the high salt content of the ambient humidity present a serious threat to any electrical equipment not properly protected. Additionally, the electrical current powering this equipment can accelerate the corrosion process, with exposed electronics becoming irreparably damaged in as little as a matter of hours once exposed to salt water.
It is not at all unusual for boaters to find themselves replacing lighting equipment every season. Traditional incandescent marine lighting contains only wiring, switches and fixtures for securing the lamps, but each of these is constructed of a different material and thus is prone to severe corrosion. Despite many manufacturers attempts to seal and protect such equipment, all too often they rely on a sacrificial methodology, where housings and sealants are expected to sustain damage while protecting the interior electrical components. The result is equipment that may last for a couple of seasons, but gains an unattractive appearance and increases in unreliability over a fairly short period of time. Although they will use materials such as stainless steel for some parts, they will also incorporate exterior materials such as zinc and copper, which are highly reactive in marine environments and will begin corroding from the moment of exposure.
Newer lighting equipment such as LEDs present an added concern as sensitive solid state electronic components are also incorporated into their design. As LEDs become more popular among boaters, it is becoming increasingly more important boaters ensure that such solid state lighting is properly constructed before choosing to install it on their craft. One of the surest ways to ensure that an LED light is going to be able to withstand use in a marine environment is to make certain it carries the proper IP rating. Known as an “International Protection” rating, this IP number relates directly to how well a device can withstand intrusion from objects and contaminants.
For marine environments, an IP rating of IP67 or better is preferable. An IP 67 rating means that a device is sealed against intrusion from water sprayed at minimal pressures and at 30 minute immersions of depths up to 1 meter. An IP68 rating designates water tightness to at least 1 meter or beyond at continuous immersion as rated by the manufacturer, meaning the device will be water tight under water sprayed at specific pressures and to at least one meter of continuous submersion and deeper depending upon the manufacturers testing.
Lights like Larson Electronics’s LEDPB10W-40E LED Boat Light are rated IP68 and manufacturer rated to submersion of up to 3 meters. Additionally, LED lights such as these incorporate additional protection against corrosion through the use of anodized coatings, powder coat finishes and all stainless steel mounting hardware, keeping disparate metallic materials to a minimum and sealing susceptible components from any contact with water entirely. Without a varied mix of exterior materials and through the use of a hermetically sealed housing, IP68 rated units such as these can withstand prolonged exposure without failure and easily survive several seasons of exposure with minimal care.
At the very least, when considering an upgrade to LED lighting on your boat, look for a rating of at least IP67 and consider the materials that will be exposed to the marine environment. This simple consideration could make the difference between a successful upgrade lasting the life of your boat and yet another season of expensive repairs and replacements.