Section 5 Machinery requirements for light ice conditions – Ice Classes 1D and 1E

5.1 General

5.1.1 Where the notation Ice Class 1D or Ice Class 1E is desired, the requirements of this Section, in addition to those for open water service, are to be complied with.

5.1.2 The requirements need not be taken as greater than those for Ice Class 1C FS.

5.2 Engine power

5.2.1 The total engine output is to be not less than determined by the following formula:

0,72LB kW

where

Rule length, in metres, see Pt 3, Ch 1, 6.1 Principal particulars 6.1.1

moulded breadth of ship, in metres, see Pt 3, Ch 1, 6.1 Principal particulars 6.1.3.

5.3 Main engine shafting and propellers

5.3.1 The diameters of the shafting and propeller blade thickness as required by the Rules for open water service are to be increased by the percentages as given inTable 2.5.1 Increase for main engine shafting and propellers. No increase in the diameter of crankshafts, thrustshafts or intermediate shafts is required.

5.3.2 The screwshaft may be tapered at the forward end in accordance withPt 5, Ch 6, 3.5 Screwshafts and tube shafts 3.5.3 and Pt 5, Ch 6, 3.5 Screwshafts and tube shafts 3.5.4 subject to the increase in diameter of 5 per cent as required by Pt 8, Ch 2, 5.3 Main engine shafting and propellers 5.3.1.

Table 2.5.1 Increase for main engine shafting and propellers

Screwshaft, increase in diameter as required by Pt 5, Ch 6, 3.5 Screwshafts and tube shafts	5%
Propeller, increase in blade thickness at root and at 60 per cent radius as required by Pt 5, Ch 7, 3.1 Minimum blade thickness	8%
Keyless propeller fitting, increase in mean torque as defined in Pt 5, Ch 7, 3.2 Keyless propellers	15%

5.4 Minimum propeller blade tip thickness

5.4.1 The tip thickness, t, of the blade at 95 per cent radius is to be not less than that obtained by the following formula:

mm.

where

blade root thickness required by Pt 8, Ch 2, 5.3 Main engine shafting and propellers 5.3.1, in mm

σ_u

specified minimum tensile strength of material, in N/mm²

5.5 Blade edge thickness

5.5.1 The edges of the blades are to be suitably thickened for the operating conditions but are to be not less than 50 per cent of the required tip thickness, t, measured at 1,25 times tip thickness, t, from the edge. For controllable pitch propellers, this requirement need only be applied to the leading edges of the blades.

5.6 Cooling water lines

5.6.1 Connections are to be fitted between the cooling water overboard discharge lines and sea inlets for main and/or auxiliary engine cooling water systems so that warm water may be used to assist in maintaining the suction pipes free from ice.

5.6.2 Where the cooling water inlet valves are fitted to a common water box, the connections from the cooling water discharge lines may be led to the water box in a position as near as possible to the inlet valves.