Capability Plots of Dynamic Positioning in Ice

Abstract

Dynamic positioning (DP) capability plots in open water are essential tools both for ship design and operational risk assessment. Currently the capability plots are widely used by the whole ship sector. Furthermore, the calculations and representations of the capability plots have been standardized by the International Marine Contractors Association (IMCA). In a capability plot, the wind, current and wave loads are taken into account and the plots are given in polar coordinates [1]. Recent research and ice basin experiments have demonstrated the feasibility of DP operations in ice-covered waters [2]. However, the design of a similar analysis tool as the capability plot is complicated by both a large range of ice parameters and the lack of understanding of the ship/ice interaction physics at low relative velocities [3]. In this paper, the influence of several ice parameters is studied in order to identify the most important variables for DP in ice. The study comprises both ice basin experiments and numerical simulations. The ice basin test results are extracted from the trials carried out at the large ice tank of Hamburg Ship Model Basin (HSVA) within the scope of the European research and development project DYPIC [2]. The numerical modelling is based on a novel high-fidelity simulation approach which is discussed in the paper. Finally, “ice capability plots” are drawn under certain hypothesis and assumptions.

A Software Framework for Simulating Stationkeeping of a Vessel in Discontinuous Ice

“…Metrikin et al (2013b) used the first version of the model for simulating dynamic positioning of an Arctic drillship in managed ice and compared the modelling results with model testing data. Later, Kerkeni et al (2013a) used the model to compare the DP control laws in open water and ice, and to establish DP capability plots of a vessel in managed ice (Kerkeni et al, 2013b). Metrikin and Løset (2013) simulated an oblique towing test of an Arctic drillship in managed ice and compared simulation results to experimental data.…”

The Arctic DP Research Project: Effective Stationkeeping in Ice

“…The thrust prioritizing allocation algorithm that was used for the DP-Ice Capability Plot analysis is presented in and . Another simulation-based procedure to generate a DP-Ice Capability plot, based on the DYPIC project, was presented by Kerkeni et al (2013), where the influence of several ice parameters for such an analysis were extensively studied.…”