Section 4 Guidance for ice environment

4.1.1 This section is intended to give guidance on the selection of a suitable ice class notation for the operation of naval ships in Arctic and Antarctic regions.

4.1.2 It is the responsibility of the Owner to determine which notation is most suitable for their requirements. Ultimately the responsibility rests with the commanding officer and their assessment of the ice and temperature conditions at the time.

4.1.3 The documentation supplied to the ship is to contain the ice class notation adopted, any operation limits for the ship and guidance on the type of ice that can be navigated for the nominated ice class.

4.2.1 The World Meteorological Organisation's, WMO, definitions for sea ice thickness are given in Table 2.4.1 WMO definition of ice conditions.

4.2.2  Table 2.4.2 Comparison ice standards defines the ice classes in relation to the Rules and the equivalent Internationally recognised Standards.

4.2.3 Extended periods are defined as those that involve the vessel remaining in air temperatures below 0^oC for more than one week.

4.3.1 For naval ships intended for extended periods of operation in Arctic and Antarctic areas the suggested ice class is 1C. For these operational limits, the materials used for hull construction are to be in accordance with Vol 1, Pt 6, Ch 6, 2 Materials. If a higher ice class is proposed, material requirements are to be specially considered using a specified design air temperature as defined in Vol 1, Pt 5, Ch 2, 3.2 Design air temperature.

4.3.2 For naval ships required to operate in multi year ice as defined by the Ice breaker region in Figure 2.4.1 Ice limits Arctic Winter without an ice breaker escort, the requirements for ice class will be specially considered. Material requirements are to be in accordance with Vol 1, Pt 6, Ch 6, 2 Materials using a specified design air temperature as defined in Vol 1, Pt 5, Ch 2, 3.2 Design air temperature.

4.3.3 The variable nature of ice conditions is such that the average limits of the conditions are not easily defined. However, it is possible to plot the probable limits of the ice flows and the ice edge for each season. Operation with Ice Class 1C may be possible up to 150 nm inside the 7/10 region shown depending on the severity of the winter. Operation with Ice Class 1A may be possible up to 150 nm inside the medium first year ice shown depending on the severity of the winter. Operation up to the multi year ice is possible most years with Ice Class 1AS.

4.3.4 Operation in the region between 7/10 and 1/10 in the arctic is possible with due care for ships with no ice class. For ships operating for extended periods in these areas it will be necessary to specify and design for a minimum temperature for the hull materials. To cover all situations for a non-ice class ship, the material requirements of Vol 1, Pt 6, Ch 6, 2 Materials are recommended.

4.4.1 Where the requirements of Vol 3, Pt 1, Ch 1 Ice Navigation - First-Year Ice Conditions are complied with, the ship will be eligible for a special features notation as defined in Vol 1, Pt 1, Ch 2, 3.9 Machinery and Engineering Systems notations

4.5.1 Certain areas of operation may require compliance or demonstration of equivalence with National Authority requirements. Table 2.4.2 Comparison ice standards gives the equivalence of National Authority requirements.

4.5.2 The standards of ice strengthening required by the Rules have been accepted by the Finnish and Swedish Boards of Navigation as being such as to warrant assignment of the Ice-Due Classes given in Table 2.4.2 Comparison ice standards. For definition of Ice-Due Classes, see Finnish-Swedish Ice Class Rules, 1985.

4.5.3 Ships intending to navigate in the Canadian Arctic must comply with the Canadian Arctic Shipping Pollution Prevention Regulations established by the Consolidated Regulations of Canada, 1978, Chapter 353, in respect of which LR is authorised to issue Arctic Pollution Prevention Certificates.

4.5.4 The Canadian Arctic areas have been divided into zones relative to the severity of the ice conditions experienced and, in addition to geographic boundaries, each zone has seasonal limits affecting the necessary ice class notation required to permit operations at a particular time of year. It is the responsibility of the Owner to determine which notation is most suitable for their requirements.

4.6.1 For ships intended to operate for extended periods in Arctic or Antarctic the build up of ice on exposed surfaces is to be considered. See Vol 1, Pt 5, Ch 3, 7 Ice loads and Vol 1, Pt 5, Ch 4, 2 Still water global loads.

4.6.2 As a minimum a full icing allowance is to be applied to vessels operating in the following areas, see Figure 2.4.5 Ice accretion limits Arctic:

• The area north of latitude 65^o30’N, between longitude 28^oW and the West coast of Iceland; north of the north coast of Iceland; north of the rhumb line running from latitude 66^oN, longitude 15^oW to latitude 73^o30’N, longitude 15^oE, north of latitude 73^o30’N between longitude 15^oE and 35^oE, and east of longitude 35^oE, as well as north of latitude 56^oN in the Baltic Sea.
• The area north of latitude 43^oN bounded in the west by the North American coast and the east by the rhumb line running from latitude 43^oN, longitude 48^oW to latitude 63^oN, longitude 28^oW and thence along longitude 28^oW.
• All sea areas north of the North American continent west of the areas defined in subparagraphs above.
• The Bering and Okhotsk Seas and the Tartary Strait during the icing season.
• South of latitude 60^oS.

4.6.3 A full icing allowance is defined as an additional pressure of 1 kN/m² (100 mm of ice) applied to all exposed horizontal or near horizontal surfaces and 0,25 kN/m² (25 mm of ice) applied to all exposed vertical surfaces. The volumetric centre of the ice is to be taken as that of an equivalent head of water. The density of the ice is assumed to be 1000 kg/m³.

4.6.4 As a minimum a half icing allowance is to be applied to vessels operating in the winter seasonal areas as defined in the international Load Line Convention.

4.6.5 A half icing allowance is defined as an additional pressure of 0,5 kN/m² (50 mm of ice) applied to all exposed horizontal or near horizontal surfaces and 0,18 kN/m² (18 mm of ice) applied to all exposed vertical surfaces. The volumetric centre of the ice is to be taken as that of an equivalent head of water. The density of the ice is assumed to be 1000 kg/m³.

4.6.6 The effects on stability of ice accretion are to be assessed in accordance with the specified subdivision and stability standard.

4.6.7 Where alternative icing allowances are specified and these allowances exceed that defined in Vol 1, Pt 5, Ch 2, 4.6 Ice accretion 4.6.3 and Vol 1, Pt 5, Ch 2, 4.6 Ice accretion 4.6.5 for the appropriate operational areas, these allowances shall be used in the assessment of the local and global structure.

4.7.1 Charts and images for the current and recent ice conditions in all areas of the world plus information on icebergs can be found from the National Ice Centre on the world wide web at

1. http//www.natice.noaa.gov/.

Information is supplied by regular assessment and survey by the naval ice centres patrols.

4.7.2 Daily ice information and consultation is available from the Canadian ice service which is part of the Canadian department of the environment. Their web site can be found at

1. http// www.ice-glaces.ec.gc.ca.