Evacuation in Ice: Field Trials of a Conventional Lifeboat in Pack and Level Ice

Abstract

Abstract Offshore exploration and production operations in sea ice conditions mustface the challenges of working in frontier environments. In the context of thecorresponding regulatory environment, operators will be expected to show thatnew technical and operational challenges have been addressed. Emergencyresponse in sea ice conditions is a case in point. In the event that marineevacuation of an installation is necessary, the lifeboat will have to becapable of being launched safely into ice, propelling itself away from thehazard area to some safe distance, and then affording a haven until personnelcan be recovered. Some ideas are presented in this paper for improving the capabilities oflifeboats and for meeting the expectations embodied in regulations. The designand operational elements contemplated here are broadly based on model scaleexperiments and full-scale trials with conventional TEMPSC lifeboats that havebeen done over the course of a multi-year test program. Design considerationsinclude powering and propulsion, maneuvering, structural resistance to iceloads, and arrangement of the coxswain's cockpit (visibility). Operationalconsiderations include the coxswain's tactics in ice, simulator training forcoxswains, and ice management of evacuation routes. Finally, the use oftraining simulators for evaluating and demonstrating the efficacy of these andother improvements is discussed. Approach A program of model scale experiments and full-scale field trials has beenunderway for a period of several years to investigate the performancecapabilities and limitations of evacuation craft in sea ice. This paper focuseson a series of field trials with a small, conventional totally enclosed motorpropelled survival craft (TEMPSC). The lifeboat was tested in pack iceconditions in an ice channel cut in landfast ice on a freshwater lake. Thechannel was about 55m long and 32m wide and the ice was between 300mm and 400mmthick (with an average measured thickness of 340mm). The ice that was cut outof the level ice sheet to make the channel was further cut into floes of twobasic sizes, the smaller about 1.65m×2m and the larger about 3.2×2m. Thesecorresponded to floes that were about 30% and 50% the mass of the lifeboatitself. The ice concentration in the channel was controlled by removing some ofthe ice floes from the channel. Several ice channel transit tests werecompleted, starting with a pack concentration of 9/10ths. At the end of thetests in those conditions, more ice was removed from the channel until thegross concentration was 8/10ths and another set of transit trials was done. This process was repeated for consecutive concentrations of 7/10ths, 6/10ths,5/10ths, and 4/10ths. The same procedure was used in model scale tests reportedby the same authors (Simões Ré & Veitch 2003, Simões Ré et al. 2006). Indeed, the field tests replicated the model scale experiment conditions to theextent practicable. The field trials were done over a five-day period in March2010.