A Radar-Assisted Collision

Electronics — December 2004
By Ben Ellison

A Radar-Assisted Collision
Get a better grip on the realities of electronic navigation by learning from the mistakes of others.

 More of this Feature
• Part 1: Collision
• Part 2: Collision
• Electronics Q&A
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Some folks are not as enthusiastic about marine electronics as I am. Thus I get the occasional letter that goes something like this, “Now you listen up, sonny; back when we all knew how to get around with just a paper chart and a compass, we were better navigators. Those gizmos get people in trouble!” Do electronics sometimes lead to problems? Absolutely yes, but you’d better examine the details before you jump to conclusions.

Thus it’s useful that some nautical accidents are examined in astonishing detail. While not commonly done in the world of recreational boating, the commercial shipping authorities analyze mistakes with almost fetishistic intensity. The results are commonly called maritime casualty reports, and while they may sound a bit ghoulish, many professional mariners read them with the optimistic goal of learning from the mistakes of others. In fact, every issue of the fine magazine Professional Mariner includes extracts of current casualty reports.

We can learn, too, and these days many agencies like the U.K.’s Marine Accident Investigation Branch (MAIB) make its full reports conveniently available on the Web. That’s where I found an investigation of a collision in the English Channel that vividly illustrates some realities of modern radar usage. The 58-page report, published as an illustrated PDF file, describes every aspect of the incident, including each vessel’s equipment and crew, and then draws conclusions and makes recommendations. Though the writing style is “just the facts, ma’am” Sergeant Friday flat, it’s a compelling read.

The 47-foot British sailing yacht Wahkuna set off from France toward home one clear morning in May 2003, but soon found herself motoring in thick fog. The owner, who had 40 years’ recreational experience and Royal Yachting Association certificates of competency, was at the helm, which was equipped with a top-of-the-line Raymarine R70 radar. Four quite experienced crew were in the cockpit with him. At around 10:45 a large target appeared about six miles off the starboard bow. The illustrations on page 40 show each vessel’s track and how Wahkuna’s radar might have looked if the target echo was perfectly “trailed” for 15 minutes.

Actually, the Raymarine had features well beyond echo trails, like a Mini Automatic Radar Plotting Aid (MARPA) function, which might have plotted the target vessel’s true speed and course, and the all-important Closest Point of Approach (CPA). Wahkuna also had a R80 radar down below at the nav station that one of the crew might have been working simultaneously. “However,” MAIB notes, “during the events leading to the accident, only the display in the cockpit area was being monitored, and…neither the skipper nor the crew fully understood, or appreciated, the information that could have been provided by the equipment.”

Meanwhile, the captain of the 908-foot container ship Nedlloyd Vespucci, who had just jogged slightly right for another target, had his Atlas ARPA radar plotting Wahkuna and had determined that she would cross his track almost a mile ahead. This man had 20 years of professional training and service, including three as master of this particular vessel type, and was so conscientious about the Channel run that he’d been on the bridge for 14 hours. He maintained his 25-knot speed.

Next page > Part 2: A mere 15 minutes after the incident began, Wahkuna’s crew saw a wall of steel emerge from the fog. > Page 1, 2, 3, 4, 5, 6, 7

This article originally appeared in the November 2004 issue of Power & Motoryacht magazine.

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