The Case of the Unwatched ZOCs


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The sea still holds many secrets,
some of them could sink you,
so watch your ZOCs .


Pacific Challenger is a German-flagged 148 metre long containership of almost 13,900 deadweight tonnes with a service speed of 19 knots and a crew of 19. Although she was built as recently as 2003 she isn’t equipped with an electronic chart display, or ECDIS. Even if she had been, her fate might not have been much different.

Pacific ChallengerAt the time of our story, the spring of 2008, Pacific Challenger has been chartered by Swire Shipping. Her first voyage under the charter will take her from the port of Rabaul on the northern tip of New Britain across the Solomon Sea to Oro Bay on the north east coast Papua New Guinea.

The Second Officer drew safety circles

The South Pacific, so redolent of Joseph Conrad and Jack London, so exotic, so unsurveyed. Strange though it may seem in this era when Google Earth can spot a bikini on a suburban rooftop there are actually parts of this globe that haven’t been surveyed since the days of Conrad and London, and in many cases since before they were born, if they ever were surveyed. Some of those places are not very deep, like parts of the Solomon and Coral Seas over which Pacific Challenger is scheduled to pass for the very first time.


Swire Shipping sent an email, with the help of Google Earth

Google Earth come into our story. Helpfully Swire Shipping, which operated the area with its own tonnage, emailed some pictures derived from Google Earth to Pacific Challenger. The distance between Rabaul and Oro Bay was at 394 nautical miles.

The second officer gets his charts and publications together and plots courses and waypoints. Carefully, he notes the reefs and shallows on the approaches to Oro Bay and draws safety circles to keep the ship clear of them. His route is fairly direct, but it isn’t the one recommended.


The planned route was direct, but not recommended

This produces a slightly longer voyage of 398.58 miles, slightly longer than the one estimated in the charterer’s emails. Next the second officer goes to the computer and puts the data into a spreadsheet and prints it out.

Pacific Challenger leaves the dock at Rabaul with a coastal pilot onboard. The Second Officer asks him if the planned route is okay and the pilot says it is. Later, the pilot disembarks and Pacific Challenger continues on to its unexpected fate.

Fast forward: Its now a little before 0900 on 9th April 2008. Pacific Challenger is heading 233 and the third officer is on watch. The master is on the port bridge wing, also on watch. A helm order is given to bring the ship a little more southerly to 221 at 15knots.

A little after 0600 the sunrise rises off her port beam glittering off the calm sea.

Suddenly, emerging from the glare of the sunlight on the clear blue Pacific is a narrow, ghostly thread of white coral straight across the ship’s course. There’s no possible way to avoid it.


Suddenly, across her bow, a ghostly white thread

There’s a shout of warning, the controllable pitch propeller is put astern but it’s too late to have much effect. At almost full speed, Pacific Challenger’s bulbous bow drives on to the white shape, the reef screeching and tearing at her double bottom for almost thirds thirds of a ship’s length, then stops. The vessel remains upright.

Cautiously, attempts are made to come free but the vessel is firmly grounded. It takes several hours before another vessel can come alongside and lighter-off some of the containers and, with the help of two tugs from Svitzer Australia, Pacific Challenger is pulled off the reef.

Fortunately, no-one was hurt and there was no pollution but the vessel needed extensive repairs including replacement of the double bottom up to about midships.

An uncharted reef, what else is there to say? Well, there is a preferred route further to the north and down the coast of Papua New Guinea which would have enabled the ship to reach ther destination without incident which is why it’s the preferred route.

Even if the area had been accurately surveyed, the chart may still not have been reliable. Earthquakes and volcanoes can suddenly change the profile of the seabed in this seismically active area, making a nonsense of any previous depth soundings.

Another good reason for taking the well travelled road.

This sort of incident is not particularly unusual and can be devastating.

A bulk carrier Sanko Harvest, grounded on an Australian reef in 1991, resulting in the country’s worse oil spill, under similar circumstances.

In 2004, a Dutch stone carrier, Rocknes, capsized with the loss of 18 of her 30 crew in part because of confusion about hydrographic information.

There are such places around the the world.

In 2006 the jack-up barge Octopus ground in the Stronsay Firth, Orkney Islands in an area that had not been surveyed for 140 years.

A year later the Louis Cruise liner Sea Diamond grounded on a Greek rock that was not properly located on the chart of the area.

In other words, in many places, charts and depth soundings are inaccurate. Many were taken by leadline using positions derived from equipment far less accurate than your GPS receiver.

ECDIS may not be any more accurate than paper charts, especially when using raster charts based on paper charts. Don’t assume that because it runs on a computer it’s more accurate. Over the next few years areas are being resurveyed to create electronic charts following International Hydrographic Organisation standards but they will only cover 800 of the busiest ports.

The chances are that such incidents will increase over the coming years as vessels, especially cruise ships, travel more and more marginal routes which are less and less well surveyed. There is a danger that growth in the use of ECDIS may also contribute to these incidents as the use of electronic charts may generate a false sense of security in the data on screen.

One solution is forward-looking sonar that can look ahead at the sea bottom but the chances are you won’t have that equipment aboard, so it’s back to basics.

Make sure you’re using the latest chart and that it is updated according to the latest notices. A failure to do that played a key role in the Joshua Slocum tragedy.

Make sure you’re using the right chart. It has been known for an OOW to skip one complete chart and not notice because the skipped chart covered one whole degree of longitude and he was using only the last figures on the GPS readout when plotting.

Make sure you’re using a chart of a scale appropriate to your speed and the area you’re in.

Take a look at the Zones of Confidence if you’re planning a course through an area you’re not familiar with, especially if it’s one that is lightly travelled. Even more so if it’s relatively shallow. and, area subject to earthquakes and volcanoes.

You might have to rummage around on your ECDIS menus to find zones of confidence and some ECDIS instruments aren’t programmed to show them at all.

If an area is unsurveyed, as it was in the case of the Pacific Challenger, then it’s certainly somewhere you should think twice about. If the survey is old and growing whiskers, then you need to think carefully about how much confidence you have in what the chart tells you.

Remember, the objective of the exercise is safe navigation. Always err on the side of safety.

In ancient times, cartographers put the warning “Here be dragons” on their maps when they really didn’t know what was there, that, too, was a sort of zone of confidence. How do you stay clear of dragons?

Watch your ZOCs.

This is Bob Couttie wishing you safe sailing.

BSU Investigation Report