## Background
### Polar Code and POLARIS  
The Polar Code was developed, in part, to address the demands associated with the operation and navigation of ships in Polar regions that are not sufficiently captured in the existing requirements outlined in SOLAS and MARPOL. The Polar Code covers the full range of design, construction, equipment, operations, training, search and rescue, and environmental protection matters relevant to ships operating in the inhospitable waters surrounding the two poles. Vessels being designed for operation under the Polar Code are required to undergo an operational assessment to establish the vessels' operational capabilities and limitations. The operational assessment follows the risk-based IMO Formal Safety Assessment [19], which forms the basis for a vessel's Polar Ship Certificate and Polar Waters Operational Manual (PWOM), and implicitly incorporates crew and environmental safety. In this regard, the Polar Code works well for vessel design and class selection. For voyage planning and real-time decision making on the bridge, the POLARIS methodology assesses the operational limitations of an ice class vessel. POLARIS was developed, in part, from experiences gained through use of Canada's Arctic Ice Regime Shipping Systems (AIRSS) and the Russian Ice Certificate. POLARIS evaluates the risks posed to a ship operating in ice based on assigned ice class and the ice regime. The ice regime may be historic or forecasted in the case of voyage planning, or it may be observed from the bridge of the ship in the case of real-time decision-making. For a given vessel class, POLARIS assigns Risk Index Values (RIVs) corresponding to each ice type, where a given ice regime can be comprised of several different ice types. The total Risk Index Outcome (RIO) is determined by the summation of the RIVs for each ice type present in the ice regime multiplied by the corresponding concentration of that ice type (expressed in tenths), as shown in Equation (1):  
\[\text{RIO}=(\text{C1}\times\text{RIV1})+(\text{C2}\times\text{RIV2})+\dots+( \text{Cn}\times\text{RIVn}) \tag{1}\]  
where C1... Cn = concentration (in tenths) of each ice type within the ice regime and RIV1... RIVn = the corresponding RIVs for each ice type. The calculated RIO governs the operational criteria for the vessel: 'Normal operation' (RIO \(\geq\) 0), 'elevated operational risk' (\(-10\leq\text{RIO}\leq 0\)), or 'operation subject to special consideration' (RIO \(<-10\)). Response measures for 'elevated operational risk' include reducing speed, additional watch keeping, or icebreaker escort, while 'operation subject to special consideration' measures include further reduction of speed, course alteration, or other special measures to reduce risk. Guidance on procedures for operational criteria should be documented in the vessel's PWOM. The POLARIS methodology was recently validated as a suitable means for assessing the risk of structural damage of ice-going vessels [12]. Two vessels were instrumented to record full-scale ice-induced hull loads and ice concentrations during their voyages. POLARIS was used to determine the optimal ice class to allow navigation in both scenarios. Optimal ice class was also evaluated based on the required hull strength to mitigate the risk of structural damage. For each scenario, POLARIS identified the same optimal ice class as the structural risk analysis. Despite the Polar Code promoting a holistic approach to risk management, POLARIS is not a single solution for operational risk management; it only accounts for the risk of structural damage. There is no consideration for the potential consequences of a ship damaged by ice. Operators require complementary tools and additional data to support a more holistic, risk-based decision-making process [20]. The intent of POLARIS is that the operational criteria for a vessel in a given ice regime corresponds to the operational capabilities of the vessel's ice class.