ARCHIVED - Testing lifeboats in icy waters
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June 08, 2010
NRC and Memorial University of Newfoundland (MUN) are studying the performance and safety of lifeboats in icy conditions to improve marine evacuation procedures in northern waters.
"Ten years ago, we started looking at how lifeboats perform in open water and then moved on to see how they perform further north in conditions of waves and ice," says António Simões Ré, a researcher at the NRC Institute for Ocean Technology in St. John's. "We thought this was an important issue to investigate because existing regulations mostly apply to big ships rather than small craft."
Since 2007, the research team has conducted a variety of field tests involving a covered lifeboat, called a totally enclosed motor propelled survival craft (TEMPSC). The researchers have looked at the performance of the lifeboat in ice conditions, the loads on its structure and propulsion system, its manoeuvring ability, and human factors involved in its operation.
During field trials, there are several issues to consider, says Simões Ré. "On the engineering side, how strong is a TEMPSC? Is the hull strong enough to absorb impacts with pack ice?" To investigate this, the researchers used a range of instruments and cameras to measure the loads impacting a boat. In addition, the research team has conducted laboratory experiments to assess both the tensile strength and limiting loads of typical TEMPSC laminates. The team is currently investigating if there are better alternatives to the current laminates.
In other work, the researchers have found that a TEMPSC lacks enough power to adequately move through some conditions, especially ice-covered waters, and "its propulsion and steering systems are not optimized," says Simões Ré. In response, the team has re-designed the TEMPSC's propeller, nozzle and engine to increase its thrust and manoeuvrability. A new engine was also installed to provide additional power. "Some of these increments aren't very expensive," he adds. "For example, a new propeller nozzle requires an investment of only $2500."
"At certain speeds, the boat will probably hit ice and get pitched if the pack ice moves," he adds. "Our lifeboats were direct drive, so we were concerned that people might jam their hands or even break a wrist from the impact on steering when ice hits the boat. To improve their safety, we installed a hydraulic steering system. But we found that coxswains now drive the boats more aggressively, which can cause serious damage to the lifeboat's steering system, so there needs to be a balance."
Manoeuvring ability and human factors
In terms of manoeuvring ability, visibility is vital, says Simões Ré. "But once you close the hatches, the coxswain has a poor view from inside the cockpit. And in some enclosed lifeboats, the cockpit is located near the stern of the boat. This is like asking a St. John's bus driver to drive through the city from the back of the bus."
Other problems they identified include a lack of windshield wipers and defrosters in covered lifeboats, so condensation can quickly build up on the windows. "It's also hard to understand today why lifeboats wouldn't have a GPS because everybody has a GPS," he says.
More disturbingly, the NRC-MUN team has identified potential health risks for passengers due to the build up of carbon monoxide and carbon dioxide levels inside a TEMPSC. "If you rely on natural ventilation, CO2 levels will be excessive for people for a long period of time," says Simões Ré. "We've also foun that noise levels can reach 100 decibels in some, but not all, lifeboats. And if you do an ergonomic assessment of these lifeboats, they fail."
This summer, Simões Ré and his colleagues are planning an open water trial to evaluate an enclosed lifeboat's manoeuvring and seakeeping capabilities using the new propeller, nozzle and engine they designed. And in a parallel project, the researchers are investigating whether a lifeboat simulator developed by St. John's-based Virtual Marine Technology can improve people's ability to steer the craft in real-world conditions.
Any recommendations from these studies will ultimately be shared with lifeboat designers, public agencies and government regulators, says Simões Ré. "In fact, some oil companies are now asking us to evaluate their own evacuation craft under real-world operating conditions."
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