Ice-induced global loads on USCGC Healy and CCGS Louis S. St-Laurent as determined from whole-ship motions.

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TypeTechnical Report
AbstractThis report provides documentation on the recently updated MOTAN system. The MOTAN uses measured whole-ship motions to obtain the global loads associated with transient ice impacts. Model-scale and full-scale data are used to demonstrate the feasibility of using the MOTAN system to provide reliable information on global loads. Whole-ship motions of the icebreakers HEALY and LOUIS, which have similar ship displacements, are used to determine ice-induced global loads for more than 200 impacts. Results show good agreement between global loads measured on the HEALY and LOUIS. Impacts with warm first-year ice at ship speeds up to 11 kt caused global loads from 1.7 to 7.0 MN. Impacts with medium to thick second-year and multi-year ice at speeds from 0.6 to 16.1 kt resulted in global loads from 1.9 to 17.3 MN. The three highest global loads on the LOUIS (15.7, 16.7 and 17.3 MN) resulted from ramming a rubbled multi-year floe at about 11 kt. The three impacts occurred in quick succession, over a period of about 5 seconds, as the ship slowed to 5 kt from 11 kt. Plotting the initial impact force (the first in a series) versus ship speed showed a clear trend of increasing global load with increasing ship speed, for the multi-year ice events. A lesser correlation was found for thick second-year ice impacts and no apparent correlation for thick first-year and medium second-year ice impacts.
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AffiliationNational Research Council Canada; NRC Canadian Hydraulics Centre
Peer reviewedNo
NRC numberCHC-TR-014
NPARC number12341004
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Record identifier341d8b91-4d2b-4f27-86cf-6778ec13264a
Record created2009-09-11
Record modified2016-10-03
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