Measured ice loads and design ice loads

摘要

The number of marine operations in ice infested waters has been increasing significantly in the past two decades. However, the level of knowledge on how ice affects the performance and safety of ships has still not been sufficiently explored. To increase the knowledge in this field more full scale ice measurements are required. In this context the Finnish Funding Agency for Technology and Innovation (Tekes) launched the PSRV full scale ice trial project in September 2011. The project aims to create a scientific basis for the design of ice-going ships. Within the project, a full scale ice trial in the Baltic Sea was conducted with PSRV S.A. Agulhas II during March 2012. During the ice trial the consortium conducted measurements on ice loads on the ship hull and propulsion system, ice induced vibration and noise, ship motions in ice, global ice loads, underwater noise, and mechanical and physical sea ice properties. For the ice load measurements three areas of the ship hull were instrumented: the bow, bow shoulder, and stern shoulder. This paper focuses on the ice loading measurements on the ship hull and a comparison to existing load prediction approaches. The load prediction methods presented here are based on the Finnish-Swedish Ice Class Rules (FSICR) and the International Association of Classification Societies' (IACS) Unified Requirements for Polar Ships. The ice loads measured during the ice trial are put into context with the design ice loads in design ice conditions. The comparison of the measurements and calculations shows a good compliance of the design line load based on FSICR ice class 1A super and IACS PC 6 on the bow area with the line load. However, at the stern shoulder the measured line load is significantly greater than the design load proposed by FSICR and IACS Polar Class 6.