Maximum ice force on the Molikpaq during the April 12, 1986 event

On April 12, 1986, the Molikpaq, a caisson-type offshore drilling structure, experienced a series of loading events when second-year and multi-year ice moved against the structure. The highest loads that the Molikpaq experienced during the 1985–86 season were during this day. Extensive ice thickness measurements had been taken in the ice around the Molikpaq prior to April 12. Thickness of up to 6 m were measured and 8 to 12 m estimated for a multi-year hummock. MEDOF panels on the outer face of the caisson and strain gauges on inner bulkheads of the structure were the primary instrumentation used to calculate forces on the faces. Detailed analysis of strain gauge and extensometer data indicated that the maximum global force on the Molikpaq was no more than 420 MN and most likely was 380 MN. This is in contrast to higher and lower values quoted in the literature for the April 12th event. Other loading events during the day when multiple strain gauges and MEDOF panels were being recorded produced global loads of the order 250 MN. Global ice pressures for the 8 to 12 m thick multi-year hummock crushing on the 59 m long east face were not greater than 0.8 MPa.