Ship Technology
Finally, the performance study also included an analysis of the shipboard
science spaces and equipment onboard both ships, based on observations and
interviews with the scientists. The trafficability and performance data will
contribute to the knowledge base available for the design of future icebreakers
in terms of ship resistance and powering and in terms of a realistic mix of ice
conditions and operating modes for high-Arctic transit. Since the expedition
completed a full transect of the Arctic Ocean from the Pacific to the Atlantic
via the North Pole, the data recorded on ice conditions and environmental
conditions will be extremely valuable in planning future high-Arctic icebreaker
expeditions.
The ice impact loads portion of the program is part of an ongoing joint
effort between the Canadian and U.S. Coast Guards to improve ice load impact
criteria for ice-going ships. Collaborative work between the two governments
to measure the pressure distribution on the hull of an icebreaker during ice
impact incidents started in 1982 with a bow measurement panel on the Polar
Sea. Since then data have been collected and analyzed from five deployments
of the Polar Sea in both the Arctic and the Antarctic, one extended deploy-
ment of the Swedish icebreaker Oden to the Arctic Ocean, and one deploy-
ment of the Nathaniel B. Palmer to the Weddell Sea in Antarctica in winter.
The measurements have provided the first insight into the magnitudes of local
ice impact pressures and how they vary with time, contact areas and ice condi-
tions. The data collected on the Louis S. St-Laurent during AOS-94 focused
on the relative magnitude of forces and pressures on three areas of the hull
structure: the bow, the shoulders and the bottom. Additionally, vessel maneu-
vering and powering data were collected for characterizing the vessel opera-
tions during the recorded hullice impact events. Data were also gathered on
the environmental and ice conditions during the events.
Data for 3217 impact events were recorded on the data acquisition system.
The system was configured such that an impact on any single measurement
area could trigger an event. In some cases, simultaneous impacts were recorded
on two or all three of the measurement areas. The greatest number of impacts
were recorded at the bow, as would be expected. Side impacts were the next
most frequent, followed by bottom impacts. If the multiple-impact cases are
taken into account, the total number of recorded impacts is 4037. Prelimin-
ary analysis has shown that the magnitude of the forces and pressures is consis-
tent with previous measurements in multiyear ice. Ongoing data analysis will
determine data trends and correlate impacts with ship operating and ice condi-
tions. Extreme load profiles will then be developed and relationships estab-
lished for the frequency, magnitude and pattern of the loads on the three
instrumented hull areas. The relationships will then be compared with those
specified in the Revised Canadian Hull Construction standards, and recom-
mendations will be made as appropriate.
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