A methodology for designing light hull structure of ice class vessels

Resumen

Polar navigation requires more powerful ships with increased hull strengthening capable of overcoming the additional resistance presented by sea ice and able to withstand the impacts of the many ice formations that might appear. The increase in capability of a ship to overcome the resistance whilst moving through ice infested waters, plus the extra weight of its structure due to the higher strengthening, requires greater power. Consequently, the added requirements needed by ice-going vessels entail higher emissions of pollutants into the atmosphere, greater initial investment for shipbuilding and huge operational costs. Hull strengthening of ice class vessels is defined by a proper Classification Society in their rules, which trend towards conservative equations (TRAFI,2016). This work describes a methodology to obtain lighter hull structures of polar vessels by using an impact model of a ship against an ice floe,based on energy methods, and focused on early stages of design (Popov et al.1967;Daley 2001;Jumeau & Riska2018). The hull structure of the bow region of an ice class ship is designed according to the Finnish-Swedish IceClass Rules (TRAFI,2016) and both results of the ship’s bow weight calculated through direct calculation and current regulations are compared. Finally, some conclusions related with weight reduction are shown.