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:
Updated:
Original:

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

pirate-marlin-logo

Pirate’s Cove Billfish Tournament

This Spring has felt a bit like a slow day of fishing but it’s almost time to time to Bait…and Switch. The Pirate’s Cove Billfish Tournaments offer something for every member of your crew. Exceptional fishing, fun times with family, old friends and new. Our run is short, our ...read more

Tusk.00_00_16_21.Still001

Tusk by Spyderco

Spyderco's Tusk knife combines a blade and marlinspike to create a multitool perfect for marine use. Made with corrosion resistant materials like titanium and LC200N steel, a nitrogen alloyed steel, and Spyderco-exclusive locking mechanisms, this knife is one of the toughest ...read more

IY11.98_fTaccola©DJI_0200

Italia 11.98 Performance-cruiser

This past winter, SAIL principal editor, Adam Cort, check out the new Italia Yachts’ new 11.98 performance-cruiser at the boot Dusseldorf show in German, and says he can attest to the fact it’s a boat more than worthy of the attention of North American sailors. Available in ...read more

01-LEAD-2017_IDALEWIS_0219

Racing: Doublehanded

I was born in 1955, and although I was a tad young to actually follow the first Observer Single-Handed Transatlantic Race, I grew up in the age of the pioneers of solo offshore sailing—Francis Chichester, Robin Knox-Johnson, Alec Rose, all Knighted for their singlehanded ...read more

newport-400c-updated

Spectra Watermakers

The world's quietest and most energy-efficient watermakers. Our product line ranges from hand operated desalinators that can make 6 gallons a day to our largest system that produces 20,000 gallons of fresh, potable water per day. Spectra Watermakers has the complete package: ...read more

CAPE-COD---Under-sails

Boat Review: Cape Cod

The concept of “daysailer” has grown ever broader over the years. These days the label can be pasted on a boat as small and simple as a Sunfish, as fancy as a 40-footer with a nice big cockpit and plenty of brightwork, or any number of concoctions in between. This Cape Cod ...read more

C-1002-600px

Sirius Signal

Be seen with the brightest SOS Distress Lights Available C-1002 Two Color Distress Light Flag & Whistle The Sirius Signal model C-1002 SOS eVDSD (electronic visual distress signal device) is the first product to be engineered to the new RTCM standard 13200.0 — accepted as ...read more