The constraints for the determination of the project characteristics of ship for navigation in freezing seas could be the specified main equipment in accordance with ship assignment and could be the special systems intended for ice forcing, etc. To the set constraints the specified functions of ship would be methodologically attributed, also, such functions, as the ship ability of ice of the certain thickness forcing, with these features to be evaluated as the increment of load and displacement in the optimization algorithm of ship design.
For ships of high ice category, in particular for ships ice-classes as follows: Arc4, 5 … 9 and icebreakers designed for operation in solid ice field of certain thickness, the critical factors in cross ice run are the next characteristics and particulars: the load line displacement, the power plant capacity, the hull shell thickness, structural elements of framing and floors, such particular as the spacing for transverse framing system, the structures of ship hull peaks and protruding parts, the special systems such as trimming system, etc.
For ships of specified Arctic categories suitable for cross of continues solid ice field of specified thickness, while retaining strength of the hull considering ice compression, it can be assumed that in this way the hull is as strong as sufficient from the point of view of safety in a collision with floating ice floes, if also, safety is ensured with navigational instruments and with the choice of safe speed based on a realistic evaluation of ice conditions, and the power required to force solid ice field would be sufficient for propulsion and maneuverability in ice.
Assumed the hierarchy of strength and propulsion in ice criteria, which means that the specified criteria are met performing the most severe constraints with sufficient engine power and hull strength of ship for navigation to cross continuous solid ice field of certain thickness.