We take a good look at what waterproof really means.
What does waterproof mean when it comes to marine electronics applications? Water-repellent, water-resistant and watertight seem similar, but when it comes to protecting property, understanding the difference can mean a lot.
We all may have a different interpretation regarding these terms, an ambiguity that can lead to improper purchases, or at least to incorrect usage, of products ranging from handheld electronics to dry suits. The difference between waterproof and water-resistant is something important to learn; the knowledge will affect how you load a stowage locker and purchase electronics.
Consider the definitions. Take an unopened Coke can in an ice chest. Unless it’s punctured, the can goes in at sunrise and comes out at dusk, and no water contaminates your cola. That’s waterproof. However, a word like waterproof can get misused, especially by a marketing agency trying to design a catchy advertisement.
Let’s rank the four terms this way:
• Waterproof: Impervious to water, the ultimate. Electronics that are exposed to weather and boat hulls better be waterproof.
• Watertight: Constructed so tightly as to be impervious to water. This applies to fittings in the transom, and hull and deck seams and joints. Leakage is possible, but not likely unless completely immersed in water (or sprayed by water) for an extended period.
• Water-repellent: A finish that resists, but does not entirely prevent, the penetration of water. Umbrellas and ponchos fit in here.
• Water-resistant: Clothing treated with durable water-repellent coatings (Teflon or silicone based) can be considered water-resistant.
Unfortunately, confusion over these definitions leads to problems (e.g., things get wet, things get ruined), and that befuddlement is most certainly not on the manufacturing side of reputable companies, especially when it comes to electronics. Design engineers at electronics manufacturers know the water tolerances of their products and label them accordingly.
Garmin International rigorously tests all of its devices to make sure they’ll survive the activities for which they are designed.
“All of our marine products are IPX7 rated and tested to pass other environmental hazards that a marine customer might encounter,” said Carly Hysell, PR/ media relations manager for Garmin International, who noted the GPSMAP 8600 series, which is offered in a 17-, 22- and 24-inch displays, is the latest offering. “Our products are also subjected to extensive temperature shock (hot to cold/ cold to hot), UV, salt and fog testing, water projected by powerful jets (power washer), etc., to ensure they are designed to survive in the harsh marine environment.”
Because electronics generate heat, sometimes the inside of a unit can fog up. That’s an unavoidable occurrence that manufacturers expect.
“People often associate ‘waterproof’ with ‘fog proof,’” said Jim McGowan, marketing manager for Raymarine Americas. “In fact, they are altogether different. Most marine displays do have some kind of ventilation in them that allows them to exchange air and equalize pressure with the outside world. This is often a very small pinhole vent that is covered (on the inside) with a piece of Gore Tex fabric. The Gore Tex allows air to flow in and out, while blocking drops of water.”
As electronic units heat up, they will expel internal air. As they cool down, they will inhale external air. If that air is moist (like anywhere outside of the desert), the unit will naturally ingest some moisture.
“They key is that the Gore Tex allows the water molecules to go back out again, either as vapor or as condensed water drops,” McGowan said. “It’s designed to allow only air to enter, and air and water to exit. Just like your rain gear or boots.”
Depending on the construction of your devices, seeing a bit of fog on the inside of the LCD can be a normal occurrence, and isn’t necessarily a cause for concern. It should burn off quickly once the unit is energized and it warms up. If you see full-on droplets or running water in there, then it’s time to be concerned.
“All of Raymarine’s latest MFDs and instruments use optical bonding technology,” McGowan said. “We fill the air space between the LCD panel and the unit’s front glass with an optical-grade clear epoxy. This gives them better contrast and clarity, and also eliminates fogging on the inside of the display, so you’ll never experience fogging on one of our devices.”
What’s the Purpose?
Other electronics are simply not intended to be used outside, and therefore are not built to IPX6 or IPX7 standards
“Some of our larger monitors are IPX6 when dash mounted, but only IPX2 when the back is exposed, due to cooling vents,” said Jeremy Schroeder, Navico’s mechanical engineering manager. Navico brands include Lowrance and Simrad electronics, and the Simrad NSS Evo2 is a recent new product. “These are often installed in the wheelhouse or flybridge. Our VHF radios are waterproof to JIS-7 (Japan Industrial Standards), which is very similar to the IPX7 standard. Some black box products that are commonly mounted below deck are IPX5.”
Furuno has a very broad product line offering including certified Navigation Suites of products for the largest super-tankers and cruise vessels down to very small radar and navigation systems for 20-foot fishing boats.
“For this reason, our products offer varying degrees of water resistance depending on the intended application and installation location,” said Eric Kunz, Furuno senior product manager. “Our light-marine MFDs and display products that are meant for various installation locations are typically labeled as ‘Waterproof and carry a tested IP56’. Typically, Furuno guarantees that any product rated as ‘Waterproof’ is protected from water ingress for the full two-year warranty period.”
Keeping it Clean
Maintenance with IPX6- and IPX7- rated products is simple. Not only are these products waterproof, but the procedures for cleaning and care have been greatly improved.
“Cleaning and maintenance on Raymarine products is pretty easy,” McGowan said. “MFDs, instruments, radar scanners, cameras, and other topside-rated devices can be flushed with fresh water when you’re rinsing the boat. Just make sure the door covering the chart reader is closed prior to rinsing. While water won’t penetrate through the card reader to the inside, the moisture is not helpful to the metallic contacts that read the map card.”
Be careful, though, because the wrong cleaning materials can scratch the exterior glass. For example, Furuno MFD “Waterproof” products utilize a toughened glass lens.
“This toughened glass has a very hard anti-reflective coating applied to it, which is very similar to mobile devices,” said Kunz, who noted that Furuno’s new TZT2 MFDs have an all-glass front and are completely sealed. “However, it is important to avoid repeatedly wiping salt crystals across the hardened glass lens, to reduce the chance of scratching it. We recommend spraying fresh water on the glass lens first, to dissolve any possible dirt or salt crystals, and then buff the lens clean using a microfiber cloth.”
There Are Limits
There are limits to waterproofness. Sea water pressure increases at a tremendous rate as the depth of the water increases, so any item that is rated as “submersible” generally comes with a depth rating (e.g., 1 meter, 3 meters). If you exceed that depth, you’re very likely to have leakage into the device.
“Another consideration for electronics, especially non-waterproof electronics, is adhering to the manufacturer-recommend ‘drip loops’ on cables connected to the device,” McGowan said. “If water hits an exposed cable on deck, the surface tension of the water can allow it to fl ow down the outside of the cable jacket to the lowest point in the cable, where gravity will make it drip off.”
A sign of a good installation is allowing a loop of cable to hang underneath non-waterproof devices so those drips fall clear of the device and don’t wind up inside it.
“Also, its good practice to seal the electrical connections to your electronics with some dielectric grease,” McGowan said. “This protects all of the contacts inside your power cable, network cable, transducer cable and more from corrosion over the years.”
Raymarine’s MFDs and instruments are tested to both IPX6 and IPX7 standards. They are fully approved for both above- and belowdecks installation and are waterproof from all directions.
“There are some products in our line that are not supposed to be out in the open,” McGowan said. “For example, some of our autopilot systems have a device called an Actuator Control Unit. It’s essentially the power supply for the hydraulic pump or mechanical drive system. The ACU is splash-proof but not intended to be exposed to the elements directly. Generally, that type of device is mounted inside the helm, in a lazarette, engine room or similar utility space that doesn’t see the elements directly.”
Raymarine’s radar scanners, thermal cameras and on-deck cameras are also tested to IPX6 and IPX7. These products are also tested for wind-load, to make sure they’ll keep working (rotating) in heavy winds, up to 100 knots.
Taking tests to extremes can ensure products don’t fail when needed most. Navico often implements water-ingress tests that are done above and beyond the IEC IP standards.
“These are often related to the harsh environment that our products encounter,” Schroeder said. “An example is heating a product and submerging it in cool water to simulate solar heating and a sudden rain shower or taking on a wave. This thermal shock, along with submersion, ensures we have robust products that will hold up for our customers.”