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April 29, 2004
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Engineer believes the danger of icebergs is underestimated
Titanic’s lesson being forgotten

By Michelle Osmond
Iceberg near the Ocean Science Centre
Icebergs, like this piece lurking near the Ocean Science Centre, are still a great danger to ships.
The Titanic disaster is far enough in the past that people are forgetting the lessons of that tragedy, says Dr. Claude Daley, professor and chair of Ocean and Naval Architectural Engineering. Not only is the risk of a ship being destroyed by an iceberg still present, he said, but it may be even higher.

Dr. Daley, who is also the director of the Ocean Engineering Research Centre at Memorial, recently finished a report titled A Study of the Process-Spatial Link in Ice Pressure-Area Relationships for the Program on Energy Research and Development (managed by the National Research Council of Canada). He concludes that in large scale collisions the ice forces – the amount of pressure exerted by the ice on the hull of a ship, for example – are likely being significantly underestimated.

Dr. Daley says ships today are better built, but are still not strong enough to withstand a collision with a large iceberg.

“People believe shipbuilding has evolved to the point where it can't happen again,” he said. “Studies have suggested that Titanic’s steel was much weaker and more brittle than modern steel. But, of course, nobody measured the ice loads on the Titanic. We don't really know how strong the Titanic should have been to survive that iceberg collision.

“I doubt if any ship afloat today, even one the size of Titanic, would survive such a collision without major flooding.”

The increased risk, Dr. Daley noted, comes from an apparent trend that can be seen in all plots of ice load data. He says the trend has been normally interpreted to mean that the ice gets softer as a collision progresses. “We ice specialists have talked ourselves into the concept of ‘softening ice’ and I'm beginning to think we've made a gross error,” he explained. “When I examined the data more closely, looking at the internal trends in the data, a very different result emerged. In fact the ice seems to get stronger as the collision progresses. This would result in much higher force predictions for large collisions.”

Bruce Colbourne, senior research officer with the National Research Council of Canada Institute for Ocean Technology, disagrees with Dr. Daley’s theories, however. He admits that although the risk has not gone away he says it is not greater than it was in the time of the Titanic.

“The damage sustained in any collision depends on many factors – one of which is the strength of the object you hit. However, other things, such as the speed at which you hit it, are equally important. Both our knowledge of the important parameters and the technology available to deal with them has improved since 1912. Just the introduction of radar has
virtually eliminated ship collisions with large icebergs as they can now be detected, and avoided.” He says it would be too expensive to build a ship to withstand a collision unlikely to occur.

“This would be akin to designing all cars to withstand frontal impacts with transport trucks. Better to invest in technology to avoid the collision and operate the vessel prudently when in areas where ice may be present.”

Mr. Colborne agreed that knowledge of ice strength could be improved. “There is considerable scatter in the available data and many interpretations of why this is and what it means. Dr. Daley has an interpretation of a particular strength effect that may illuminate one important piece of the puzzle. However, if a 20,000 tonne ship runs square into a 100,000 tonne iceberg at 16 knots, it will make very little difference to the damage sustained by the vessel whether the ice gets a little harder or a little softer as the collision progresses. It will still be one heck of a collision.”

 


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Annika Haywood and Dr. Brian Stavely
Iceberg near the Ocean Science Centre
(L-R) Cynthia Caddigan and Deirdre Cooper

Next issue: May 20, 2004

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