Section 4 Hull requirements for light ice conditions – Ice Classes 1D and 1E

4.1.1 The requirements for strengthening the forward region for Ice Class 1C FS are applicable. See Pt 8, Ch 2, 6 Hull requirements for first-year ice conditions – Ice Classes 1AS FS, 1A FS, 1B FS, 1C FS and 1D.

4.2.1 These requirements apply to ships with length less than 150 m and which are intended to operate in very light first-year ice conditions. Where additional strengthening is fitted in accordance with the requirements of this sub-Section, the notation Ice Class 1E will be assigned.

4.2.2 The requirements for shell plating need only be applied in the shaded region shown in Figure 2.4.1 Extent of application of plating requirements. The requirements for framing need only be applied forward of the flat of side.

4.2.3 For longitudinally framed ships, the scantlings of shell plating and framing are to comply with the requirements of Ice Class 1C FS using 0,9 times the ice pressure.

4.2.4 For transversely framed ships, the requirements of Pt 8, Ch 2, 4.3 Shell plating are to be applied.

4.2.5 Where the structural requirements of Ice Class 1C FS give lesser scantlings than the requirements of this sub-Section, the lesser scantlings may be applied.

4.3.1 The shell plating thickness within the region shown in Figure 2.4.1 Extent of application of plating requirements is not to be less than:

where

4.4.1 The section modulus of main frames forward of the flat of side is not to be less than:

but need not be taken as greater than:

where

4.4.2 Intermediate ice frames are to be fitted in the region forward of the flat of side and are to extend from 0,62 m above the upper ice waterline to 1 m below the lower ice waterline.

4.4.3 Intermediate ice frames aft of the collision bulkhead are to have a section modulus not less than 65 per cent of that given in Pt 8, Ch 2, 4.4 Transverse framing 4.4.1.

4.4.4 Intermediate ice frames forward of the collision bulkhead are to have a section modulus not less than 40 per cent of that given in Pt 8, Ch 2, 4.4 Transverse framing 4.4.1.

4.5.1 Forward of the collision bulkhead, in single deck ships, an ice stringer is to be fitted approximately 0,25 m below the upper ice waterline and is to have scantlings in accordance with Table 5.4.4 Primary structure forward in Pt 3, Ch 5 Fore End Structure.

4.5.2 Aft of the collision bulkhead a series of tripping brackets are to be fitted at each main and intermediate frame at the same level as the ice stringer to a distance 0,1L aft of the flat of side.

4.6.1 The rudder and stern frame scantlings are to be in accordance with Pt 8, Ch 2, 6.7 Rudder and steering arrangements.

4.7.1 Weld connections to the shell plating forward of the collision bulkhead are to be double continuous.