Can You See Me Now?

Many cruisers believe it’s best to locate a radar reflector as high as possible, perhaps even at the top of the mast, for better detection. However, the key issue for a radar reflector is the water-surface reflection, which affects the strength of the reflected signal. When the reflection is increased, the reflector is more apt to be seen. If reflection is reduced, a reflector could become
Author:
Publish date:

Many cruisers believe it’s best to locate a radar reflector as high as possible, perhaps even at the top of the mast, for better detection. However, the key issue for a radar reflector is the water-surface reflection, which affects the strength of the reflected signal. When the reflection is increased, the reflector is more apt to be seen. If reflection is reduced, a reflector could become invisible to radar.

How large a reflector appears to a marine radar depends on three things: the height of the radar antenna, the height of the reflector, and the distance between the two. For example, a 40-foot sailboat with no reflector should be detected by a low-power radar on a small powerboat at 0.7 mile, by a mast-mounted low-power radar on a sailboat at 2 miles, and by a ship with high-power radar at 6 miles. A typical reflector mounted 16 feet above the water increases these detection ranges to 1.7 miles, 4.6 miles, and 11.5 miles, respectively.

When approaching the small powerboat, the target sailboat passes through alternating zones in which it is visible or invisible to the low-power radar. If the target’s reflector is mounted at the masthead—say, 50 feet above the surface of the water—the detection range increases from 3.5 miles to 5.4 miles. But the reflector can become invisible at a range between 2.2 and 2.7 miles. The high-power radar on the ship would first see the target sailboat at about 15 miles, but not between 9.5 and 11 miles out or between 6.6 and 7 miles out. Both blind spots, or zones, would be eliminated if the target’s reflector was just 16 feet above the water.

While a masthead-mounted reflector does increase maximum detection range, it can also make a boat invisible to a high-power radar over 25 percent of the total detection area created by a reflector mounted 16 feet above the water. In other words, mounting a reflector higher increases the maximum range at which it can be detected, but the reflector will be invisible to a radar in significantly wide areas. Being detected at long range for a short period of time is nice, but being invisible periodically at shorter ranges might be detrimental in a closing situation. This is why mounting a reflector 16 feet above the water produces the best combination of maximum detection range and minimum blind zones. Phillip Gallman

Related

190205BeneteauFirst18

Beneteau’s new First 18

Beneteau’s new First 18 is a boat born to introduce you to the joys of sailing. This meticulously crafted sailboat is mellow enough for a great afternoon of cruising even in the lightest breeze. And when the wind picks up, she is also capable of thrilling speeds while delivering ...read more

Corsica

Charter Directory

Broker/Worldwide A2A YACHTING – Yacht Charter Worldwide A2A YACHTING +44 (0) 121 285 9009 Bajor Yacht Charters 800-524 8292 BoatBureau Charters +44(0)2033 933 878 Charter Sailing Unlimited 888-856-8310 CharterWorld world.reservations@charterworld.com Dream Yacht Charter 866-469 ...read more

Nathan-Bates-San-Diego,-CA

SAIL 2018: Reader's Photographs

Are you out there sailing, cruising and living the sailing life? If so, we’d love to see it. Send your sailing photos to sailmail@sailmagazine.com And don’t forget to sign up for our free eNewsletter. Check back for updates! We pulled out the drone to take this shot while ...read more

shutterstock_1158262783

A Catamaran Takes on the American Great Loop

After completing the European Great Loop on our 1987 40ft Catalac catamaran, Angel Louise, my wife, Sue, and I sailed home to the States and spent two years sailing up and down East coast between Maine and Florida, like migratory waterfowl. Eventually, though, we decided to ...read more

01-LEAD_Alex_Irwin

Mirabaud Yacht Racing Image Competition

The Mirabaud Yacht Racing Image competition once again captures the excitement that is sailing from around the world An impressive 109 photographers from 25 countries took part in last year’s Mirabaud Yacht Racing Image 2018 competition. And while Portuguese photographer Ricarado ...read more

judges2-1024x319-0219-600x

2019 Pittman Innovation Awards

For the past couple of decades, the digital side of sailing has become increasingly important, to the point where it’s now almost inconceivable going offshore, even aboard a daysailer, without at least a modicum of electronics onboard—a trend that has been very much in evidence ...read more