Canadian Yachting December 2015 - (Page 32)
Pinging the Unknown
A look at the technologies that
support modern marine radar
By David Schmidt
unshine flooded the waters separating California's
Catalina Island from Channel Islands Harbor, and
Capt. Tom Petersen, skipper of the well-equipped
Sea Ray 55 Sundancer Valkyrie, was leading a small flotilla
when an unexpected fog bank quashed visibility. While
Valkyrie carries the latest Raymarine kit (Petersen is a
Raymarine Pro Ambassador), including a 12 kW, six-foot,
open-array high-definition radar, Petersen's companions
weren't electronically fortified.
"I sat behind the other boats, watching them on my radar and
maintaining radio contact," said Petersen. One boat didn't have
radar or autopilot, and the skipper was ignoring his compass. "I
told him to keep [maintaining] a certain angle, but he picked up
speed and went in the wrong direction. Then, he got scared."
Staying calm, Petersen advised the panicked skipper to cut
his speed, and he expertly used his radar to wend Valkyrie alongside. "Without radar this would have been dangerous," advised
Petersen, who shepherded the fog-tossed vessel back to the
flotilla. "Your eyes can only do so much in the fog."
Raytheon delivered the world's first commercial/recreational
radar after WWII, and other systems followed, including nowgeneration systems that use high-definition (HD), broadband
and Wi-Fi technologies to improve both radar imagery and the
user interface. Still, these latest-and-greatest offerings use traditional radar technology as their basic foundation.
C a n a d i a n Ya c h t i n g
Furuno's new DRS4W 1st Watch Wireless Radar sends radar
imagery to Apple wireless devices such as iPads and iPhones
via the vessel's Wi-Fi rout.
Traditional or "pulse-modulated" radars emit extremely short
(typically, one microsecond or less) pulses of radio-frequency
(RF) energy that are generated by the system's magnetron and
transmitted via a fixed-mount, rotating directional antenna.
These pulses move at the speed of light in a narrow, horizontal
band before bouncing off targets and boomeranging as an echo.
Once received, the radar determines the range to a target by precisely measuring the elapsed time between a transmission and
an echo's return; bearing is calculated by measuring the radar
antenna's angle when the echo is received. Finally, the system
applies filters to sift-out signal noise (e.g. breaking waves or rain)
before presenting this imagery on an electronic display.
Table of Contents for the Digital Edition of Canadian Yachting December 2015
Vantage Point: The Wave of New Boaters is Starting!
Waterfront: What’s your Watermark? Seafaring Santa holiday gift ideas.
Club Profile: Stony Lake Yacht Club
CPS: Seamanship Courses
Feature: Binoculars - Everything you could possibly want to know about understanding, using and buying binoculars for marine use. By Rob Macleod
Electronics Feature: Pinging the Unknown - A look at technologies that support modern marine radar. By David Schmidt
Destination: La Marina, Casa de Campo, Dominican Republic - Luxuriate in this profile of the Casa de Campo, a 7,000-acre resort located in La Romana on the southeast coast of the island and boasting a port, a heliport and an airstrip and home of one of the best billfishing spots in the world. By Elizabeth Kerr
Destination: St John River - Offering cruising areas that are as inviting as any protected inland lake or river, the 75 miles between Saint John and Fredericton make for any easy weekend cruise but there are also many side trips which can occupy you for as much time as you have available. By Glen Cairns
Galley Guys: Krates
Power Review: Neptunus 62
Crossing the Line: The 6th Great Lake
Canadian Yachting December 2015