40.1.1.1 Introduction

Ships whose missions take them into ice-covered waters must be designed to operate effectively in an environment distinguished by cold temperatures, often remote location, and the presence of sea ice. Sea ice can be from a few centimeters to several meters thick, take on a variety of morphological forms, and change on daily, seasonal, and annual bases.

The transportation requirements that drive conventional shipping demands also prevail in ice-covered waters. Consequently, the ship types and missions of many ice-capable vessels correspond essentially to conventional ships. Ice-breakers and ice-management vessels are unique ship types that are designed specifically to operate in ice, usually in support of transportation services or infrastructure.

Early ice-going ships were basically similar to conventional ships with the addition of some hull strengthening. Modern commercial requirements to extend the navigation into areas and seasons with greater ice thickness and coverage have led to a commensurate extension of vessels' ice navigation capabilities. The impact on hull form, structure, propulsion, and auxiliary systems that operating in ice will have on any particular vessel is a function of its mission.

To describe the mission of ice-capable ships, the approach taken here is to describe first the environment and then typical operational...