Now high-tech navigation more affordable, available


June 05, 1994|By GARY DIAMOND

There was a time when only commercial and charter fishermen could afford the luxury of Global Positioning System or Loran-C electronic navigation equipment. Fortunately, this is no longer the case.

GPS technology was developed by the Department of Defense. It relied on a constellation of satellites orbiting the earth that provide precise information on time and location. It was high tech, and high cost.

However, new GPS receivers and technology are reaching out to encompass more boaters from the smallest fishing boats to the biggest ships at sea. Now, GPS receivers are less expensive, feature-rich and easier to use than ever before. High-resolution graphics, built-in plotters and ease-of-use now are standard on GPS navigation products.

The fastest-growing segment of GPS receivers are portable, hand-held units, portable receivers offering lots of advantages. They can be used on a boat or on shore, or taken from boat to boat. In addition, portables offer a complete range of navigation information from latitude/longitude, to waypoint definition and storage, to plotter screens that allow even a novice to navigate from point to point in any weather, day or night.

Using latitude and longitude, GPS receivers display information on position, bearing, distance to destination, speed over ground, cross track error, estimated time of arrival and a number of other useful readouts. With the ability to store up to 100 named waypoints in memory, anglers can use the waypoint database to record their favorite fishing spots, underwater structure and other locations. For example, a saltwater angler can confidently head offshore to his favorite fishing grounds and using a GPS receiver return to the same spot time and time again. In the event of bad weather, you can safely and quickly find your way to home port.

Fresh-water fishermen can identify the location of fish-holding structures on their favorite lakes and follow their electronic bread crumbs back to these top producing spots, day or night.

Some of the more sophisticated units have huge memory banks of NOAA charts that provide detailed information on marinas, depth contours and navigational aids in thousands of areas throughout the world.

With a cursor key, you easily could home in on great upper bay fishing locations, plot a course to them, and if it's connected to an auto-pilot, sit back and relax while the system takes you to your destination. It only takes the push of a button for the captain to display routes, track progress and safely maneuver in and out of harbors, across oceans and between known points.

While the features and benefits of this new generation of GPS receivers have dramatically increased, the receivers have become more affordable. Prices currently range from about $500 to about $1,500, depending on available features.

Loran-C has been around for a while.

Unlike the satellite-based GPS navigation system, Loran-C uses a series of land-based, low-frequency radio beacons. The waveform of each station is plotted and the time it takes for the signal to be transmitted and then received is measured. Three stations are received simultaneously by your Loran-C.

The signals then are processed by the systems onboard computer, and the difference in time is converted to either latitude and longitude or Lines of Position (LOP). The accuracy of Loran-C is approximately 1/100th of a nautical mile (60 feet). The accuracy of most GPS systems used by boaters is plus or minus 100 feet.

Competition has forced the price of Loran-C navigational systems to an all-time low. Compact units not much larger than a pack of cigarettes sell for as little as $249 while more sophisticated models go for $750, substantially less than GPS.

The main difference between GPS and Loran-C is interference. Because GPS receives its signals from orbiting satellites operating on very high frequencies, interference from other broadcast systems is negligible. On the other hand, Loran-C operates at low AM frequencies, thus it's subject to interference from thunderstorms and low-frequency transmission by the U.S. NTC Navy. In fact, most lorans can not function within sight of the radio towers at Annapolis or Solomons.

How does this all relate to boaters in Harford County? If you launched your boat at Tydings Park in Havre de Grace, and wanted to go fishing at Fairlee Creek, without these navigational devices, the trip would involve running from buoy to buoy in a zigzag course.

Had you been able to travel in a straight line from point A to point B, the distance would've been about 30 percent less. Fuel savings alone during one season likely would be sufficient to pay for the device.

Freshwater anglers also benefit from these devices. If you were looking for a particular piece of underwater structure at Conowingo Lake, and the only electronics onboard was a depth finder, the task could take all day. With a hand-held GPS or Loran-C, the angler merely inputs the coordinates with the keyboard and the built-in computer tells them exactly where the structure is located.

Baltimore Sun Articles
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.