What to Watch
Keeping Tabs on your ship’s systems has never been so simple.
The DSM250 from Maretron taps into the NMEA 2000 network to show custom data configurations.
I’m sure there are more than a few of us who don’t know whether 25 on the oil-pressure gauge is cause for alarm, concern, or celebration—never mind what is normal and what isn’t on some of the more obscure instruments. If the exhaust pyrometer is reading 700, is that good or bad?
And yet, for years—decades, even—boatbuilders have been devoting prime helm-station real estate to dials that most of us seldom look at and few of us understand, while other, more important instruments and controls get relegated to more distant or less accessible parts of the panel.
But now, thanks to several advancing technologies, all that is changing. The latest generation of multifunction instruments (MFIs) are easy to install and have colorful, versatile screens that show information clearly and are simple to configure.
You could, for instance, have a pair of MFIs set up to display navigation information such as a large graphic compass display on one and a rolling road, speed, and time to waypoint on the other. Then when you get to your chosen fishing spot, a press of a button could switch the same instrument to another preconfigured display showing graphs of the water depth and temperature plus digital readouts of wind and boat speed.
Suppose, on your way back, an engine-alarm screamer goes off. No problem: Another press of the “page” key—or whatever your particular manufacturer has chosen to label it—and your two MFIs transform into engine panels, with each one showing as much engine data as a dozen conventional gauges.
The key to all this is the coming-of-age of NMEA 2000, the marine-data networking system that was launched almost exactly ten years ago and now, after getting off to a very slow start, is catching on with boatbuilders and engine manufacturers. Far more closely related to the data-networking systems used in automobiles and trucks and automated industrial processes than to its predecessor (NMEA 0183), the new (or at least newish) system allows many different sensors to feed information into a single network and accommodates many different instruments to display it. (For a more complete explanation of network protocols, see here.)
So you might have a weather station on the flying bridge, a compass under the saloon sole, all the usual engine- and generator-monitoring sensors in the engine room, and speed and depth transducers in the hull, all connected to a five-core “backbone” cable, less than a half-inch in diameter. Multifunction displays (MFDs) and MFIs can pull information off the network and display it on the flying bridge, lower helm, or pretty much anywhere else that it is required, all using standard connectors and plugs.
Getting data into a display, of course, is only part of the story: It’s no good if you can’t read it! Until recently, that was one of the great strengths of traditional engine gauges and one of the great weaknesses of the liquid-crystal displays (LCDs) used for navigation instruments: Traditional gauges are easy to read in daylight, are still legible even in direct sunlight, and need only simple lighting to stay legible in darkness.
LCDs are more complicated. They need more sophisticated backlighting, usually provided by miniature fluorescent tubes but increasingly, in the latest versions, by light emitting diodes (LEDs). The beauty of LEDs is that they produce a brighter but more easily dimmable display, with better contrast between light and dark. They use less power to do it, and waste less of that power in producing unwanted heat.
But until recently, LCDs have suffered from a number of more intractable problems: reflections, narrow viewing angles, and blackout when viewed through polarized sunglasses. All three have been largely resolved by the use of high-tech films or coatings applied to the screen.
Take the polarized-sunglasses problem, for example. All LCD screens emit polarized light; it’s a fundamental feature of the way they work. Polarized sunglasses will allow polarized light to pass through but only if the light waves are polarized in the same direction as the sunglasses. If the two don’t match, the screen looks gray, and if they are 90 degrees apart, the screen may well look like a plain black rectangle. One common way to minimize the problem is to design the LCD screen so that the light emerging from it is polarized at about 45 degrees from vertical. That way the effect won’t be too bad regardless of whether your sunglasses are horizontally or vertically polarized. But a newly developed depolarizing film is providing manufacturers with a much better alternative: It scrambles the light emerging from the display back into something very similar to the random polarization of natural light, so it eliminates the effect altogether.
Of course, this still doesn’t tell you what your gearbox oil pressure should be. But at least now you’ll be able to read what it actually is.
This article originally appeared in the January 2012 issue of Power & Motoryacht magazine.