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Electronics - 2008

There’s an old joke about an angler coming in with a nice catch...

There’s an old joke about an angler coming in with a nice catch. When asked where he caught his fish, he replies, “Why, right here. See the X mark I wrote on the side of my boat where I caught ’em?” Ask the same question of an old-time angler, though, and you may instead get something like, “Put the day marker in front of Ann Taylor’s house under that fuzzy tree beside Donnie Jones’ house.”

In fact, old-time sailing-ship captains used the same system of lining up visual ranges to navigate inlets and river mouths. Some of America’s earliest charts included such instructions. This method of “taking marks” still works as valuable local knowledge. Also valuable is a basic understanding of navigating using paper charts. But there’s serious new technology, too.


Step aboard for a look at the future of navigation: integrated systems, chart plotters, digital radar and 3-D images. Read the other stories in this package: Electronics – Roundup   Electronics - Sources   Electronics – Furuno   Electronics – Raymarine   Electronics – Solar flares

There are many situations in which it’s useful for us to know exactly where we are. While taking marks is still an invaluable skill, the advent of inexpensive, accurate GPS receivers gives us a powerful new tool with much broader application and ease of use, especially in situations of reduced visibility. These remarkable machines receive timed signals from a dedicated array of satellites, then solve complex three-dimensional geometric equations to pinpoint the locations of our boats.

The system was developed for the military in the 1970s and ’80s. Back then, at least one officer (who doubtless now prefers to remain anonymous) remarked that he could not see any civilian application for the technology, a stunningly shortsighted opinion in light of the fact that GPS is now standard equipment on everything from commercial airliners and tractor trailers to kayaks and hikers’ backpacks.

Originally, the receivers caught signals from three to five satellites and gave us only latitude/longitude numbers, though by taking positions every few seconds they could tell us our direction of travel and speed. Then came “plotter” screens that showed a succession of positions with black dots on a gray screen. Changing the scale on these early plotters, however, could take as long as 30 seconds with the slow processors of the day, and the number of position points they could save in memory was limited.

Today, most GPS units, including small hand-helds, receive signals from 10 to 12 satellites, two or three of which are part of the Wide Area Augmentation System, or WAAS, which corrects small inaccuracies in the main system. Meanwhile, exponentially faster processors and greatly expanded memory allow virtually all of them to display a boat’s position on a geo-referenced map background that may contain great detail of land and water features, including aids to navigation, depth contours and overlaid aerial photographs. Thus the origin of the term “chart plotter.”

Getting started

Learning the basics of using a GPS/chart plotter is easy, though advanced applications take time as you find more and more uses for even a basic unit. At the simplest level, it is always valuable to see a boat’s position and direction of travel on a chart. Whether on a short run or an extended cruise, it’s also simple to move the screen’s cursor from the boat to the next destination. The microprocessor in the GPS will compute and display the course and distance to that mark.

The next step is to build such “point and shoot” navigation into a route that includes the sequence of marks or waypoints necessary to navigate the length of the trip, and to save it in the GPS’s memory. Building routes has become an essential element in cruise planning, and sport anglers use it to work out the most efficient ways to get to their prime spots or to troll along a productive bottom contour. Today, a low-priced chart plotter can store 1,000 waypoints and 100 routes, which are more than most of us will ever use. High-end units can hold more than twice as many.

The manuals for these machines can seem intimidating. Fortunately, most manufacturers also provide some sort of quick reference guide that is enough to get even a rank beginner started. From there, the aspiring electronic navigator should go out and put the machine to work on the water, learning to use the basic functions. A week’s time with the unit should be enough to build confidence and raise curiosity about advanced uses. While the big manual will be useful for learning, the best overall teacher is time on the water.

Making choices

The LCD screens in today’s GPS/chart plotters offer far more detail — even at the lower price points — than earlier units. A few of the lowest-priced units still have grayscale screens. They offer an attractive alternative to a boater on a tight budget, but the cost of color screens — and their visibility in direct sunlight — have improved greatly.

Today, most fixed-mount GPS units run electronic charts loaded onto small memory cards (or preloaded in the unit itself). Chart detail is remarkable. Again, credit faster processors that accomplish nearly instantaneous screen redraws when zooming in and out. As useful as grayscale screens still are, color definitely makes it easier to see chart details on a plotter screen.

GPS also figures in a remarkable new system with VHF radios that offers enhanced safety to boaters, as well as a way to privately communicate the location of a patch of fish to a friend or keep track of several friends’ boats on a club cruise. It’s Digital Selective Calling (DSC), a relatively new feature of VHF radios that, when interfaced with GPS, can quickly communicate a distress call that includes your boat’s position and identity to the Coast Guard. If both radio and GPS are the same brand, there may be a plug-and-play hookup between them. Otherwise, you may have to connect a couple of wires between the two.

At least one manufacturer has now simplified this process by offering a GPS/chart plotter with a built-in DSC VHF. It also accepts the input cable from the company’s “black box” fishfinder, a compact unit that relies on the chart plotter as its display. Another combination that has been available for at least 15 years is a GPS/chart plotter with a built-in fishfinder. It’s also possible to interface radar with a GPS/chart plotter. In fact, most of the marine electronics manufacturers now offer combination systems, including stand-alone plotters into which you can plug a variety of sensors. Here are some examples of what is possible.

Got $25,000 to spend? You can get a pair of 20-inch daylight-viewable color LCDs to mount side-by-side at the helm, networked with an Ethernet connection that will also allow you to connect a laptop with remote Internet access. Plug in a GPS receiver with WAAS and a chart card that can overlay a NOAA chart, an aerial photograph and a 3-D image of the bottom on your location. Add a radar sensor, and you can overlay that too.

Now plug in an AIS (Automatic Identification System) receiver, a 1-kW digital depth sounder, an antenna to catch weather broadcasts from Sirius or XM satellite radio, an autopilot, DSC VHF radio, and video cameras trained on your engine room and the boat’s quarters so you can keep an eye on them while running and docking. Oh, and add a TV antenna so you can watch the Red Sox and the Yankees on the helm displays while you’re on the water.

What? You don’t have room for all that at your helm, let alone $25,000 to buy it and have it installed? You’ll just have to settle for an electronics setup that would have been considered state-of-the-art five or 10 years ago. For around $750, you can buy a combination WAAS GPS/fishfinder with a chart chip and a highly visible 5-inch grayscale screen that offers position accuracy to within 12 feet, power to read baitfish on the bottom in 200 feet of water, software that runs both of these functions smoothly, and clear readings at speeds to 30 knots, plus a DSC VHF with antenna.

What’s more, you can install this rig yourself on the console of a 17- to 20-footer with simple tools and a careful reading of the instructions. Add $150 and you can have a daylight-viewable color screen on the GPS/fishfinder. Need radar? You can get a competent entry-level rig for $1,100 and interface it with your chart plotter. Now look at all the electronic capability you have gotten for less than a 10th of the big rig described above. It seems that marine electronics manufacturers give us more value for our dollars every year.

Remember, though, that none of this electronic wizardry has ever put a fish on a hook or brought a boat home safely by itself. The equipment is useful only to those who learn how to apply the information it provides. The key to setting up an effective electronics system for your boat is to think about what you need a GPS/chart plotter and the other machines to do, finding a good (though not necessarily expensive) unit that can fill that need, and then learning to use it well. GPS/chart plotter technology is developing so fast that it’s impossible for any specific machine to remain state-of-the-art for long, but that fact shouldn’t deter you from making a purchase. Be sure to select and buy the best unit you can afford, then learn it thoroughly. Even a simple unit will give you great service if you spend time with it.