Visitors to coastal Maine expect to see the flotillas of lobster boats and fishing trawlers but are often surprised by the number of pleasure boats they encounter in the land of abbreviated, foggy summers. They notice that a majority of the pleasure boats are still traditional in design, displaying the lobster-boat DNA that's in their heritage. And finally, they also see something else: Nearly every boat big enough to support one has a gleaming-white radar antenna topside.

Once upon a time, radars were limited to ships and large yachts, and for a good reason: Radar systems weighed hundreds of pounds, contained a glowing forest of power-hungry vacuum tubes, and displayed their output on a little green screen that was so dim it had to be shaded from light in order to be seen. Later, "miniaturized" systems could be installed on somewhat smaller boats but remained heavy and still required the TV-sized display box with a hood over the screen. But soon technology came to the rescue.

Now, with flat-panel screens and integrated circuits, even the smallest center-console boat can be conveniently and inexpensively equipped with radar. Anyone who navigates at night or cruises in areas where fog is a frequent foe can enjoy the protection of radar. There's a great sense of security in being able to "see" other boats, nearby land, obstructions, buoys and other aids to navigation. Most modern systems are plug-and-play, which makes them easy to install, but it's not enough to just mount it to the display, bolt it on the radome and connect it. The components of a radar system must be carefully situated, properly installed and accurately aimed to provide the maximum benefits. 

Most radar systems are made up of a radome, which encloses the rotating antenna, and the transmitting and receiving circuitry. A cable connects the circuitry to the display, which houses the brains and controls of the system, and the monochrome or color viewing screen. Power and any GPS inputs are also connected to the display.

Choosing a position for the radar display can be tricky, but it's critical to the success and usefulness of the system. It can be tempting to put it into the first available space, but the positioning will serve you best if it's as close as possible
to your other navigation instruments. Putting it too close may have adverse effects, so be sure to read the manufacturer's instructions carefully before you start drilling any holes.

Some displays, especially the LCD screens, lose their readability if viewed from too great an angle, so face the display as directly as possible to the operator. If you're going to mount it overhead and you wear bifocal glasses, be aware that you'll be viewing the screen through the distance part of your lenses, and position it accordingly. In all cases, the distance from the operator is critical; you must be able to read the display easily from your normal position at the helm. Polarized sunglasses can enhance your vision in the fog, but remember that they can also make reading the LCD display tricky, so adjust its position with your shades on.

Mounting the radome is less tricky but still must be done with care and forethought. Whether you mount it on the top of the cabin, on an arch or atop a pole, the radome should be as far from your VHF antenna as possible to prevent interference between the two systems. Its field of forward "vision" shouldn't be obstructed by any substantial structure, especially a metallic one. 

The radome's rotating antenna provides 360-degree horizontal coverage. Vertical coverage, however, is restricted to about 25 degrees, which means that the belt line of the radome should be aimed no higher than the horizon while the boat is underway. Since many smaller boats assume a bow-up position while underway, the radome may have to be mounted so it's actually aimed downward while at rest. If it's aimed too high, it will fail to detect objects that are close to you. If it's set too low, it will miss objects that are farther away. It must be aimed to accommodate the angle of the boat when it's operated in restricted visibility at a slower speed. If the radome is mounted on a boat that assumes a higher angle when running in the 10- to 12-knot speed range, a larger correction will be necessary.  

In spite of their advertised coverage distances, most onboard radar systems are limited to just beyond the horizon, and even then, most skippers run them on one- to three-mile range settings, concentrating on objects that present a more immediate danger than those that are still 10 miles away. 

Wiring cables with pre-attached connectors to connect the display to the radome are usually supplied with the system, but routing the cable during installation must be done with care. Most manufacturers advise that the cable should be separated from VHF antenna wire, shore-power wiring and other conductors, which may interfere with the operation of the radar system. The wiring used to bring 12-volt power to the unit must be protected by a fuse or circuit breaker and rated for marine use. Both the wire and the fuse must be the proper size to carry its current requirements, which will be listed on the unit or in the manufacturer's literature.
 
The final step when equipping your boat with radar is to educate yourself about the product. The design of modern units has all but eliminated the problem of fussy tuning and setup the old ones required, but there's still a learning curve. The best approach is to read the manual, and follow up by using the radar during good weather to become familiar with its operation and its output. Learning to use it in conjunction with other navigation aids will give you a comfortable leg up the next time a fog descends out of the blue.

Quick Tips

1.  Position the radar display close to other navigation equipment.
2.  Face the display as directly as possible to the operator.
3.  Place the radome far from the VHF antenna to avoid interference.
4.  Protect wiring cable with a fuse or circuit that's rated for marine use.
5.  Use the radar during good weather to familiarize yourself with its operations.