Section 3 Strengthening for navigation in ice
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Inland Waterways Ships, July 2022 - Part 3 Ship Structures (General) - Chapter 9 Special Features - Section 3 Strengthening for navigation in ice

Section 3 Strengthening for navigation in ice

Parent topic: Chapter 9 Special Features

3.1 General

3.1.1 This Section applies to all ships for which the class notation ‘ICE’ is desired. The class notation ‘ICE’ is intended for ships navigating in light ice conditions. The requirements of this Section are to be complied with in addition to the Rule requirements so far as applicable for the particular type of ship.

3.1.2 The Regulations for classification and the assignment of class notations are given in Pt 1, Ch 2 Classification Regulations to which reference should be made on the survey request form.

3.1.3 The requirements of this Section are applicable when transverse side shell framing is adopted. Special consideration will be given to proposals for longitudinal framing.

3.1.4 Ships specially designed for ice breaking duties will be individually considered.

3.2 Definitions

3.2.1 Ice belt is that part of the shell structure in the forward region which has to be reinforced. The longitudinal extent aft of this ice belt is the greater of the following:

  1. From the forward perpendicular to aft for a length equal to the breadth of the ship.

  2. From the forward perpendicular to aft where the ship reaches its greatest breadth plus 10 per cent of that distance.

The vertical extent of this ice belt is from 300 mm below the light waterline to 300 mm above the load waterline. Swim ends forward are part of the ice belt over their full vertical extent.

3.2.2 Light waterline is the lowest waterline, on which the ship is expected to navigate, taking account of trim.

3.2.3 Load waterline is the deepest waterline on which the ship is expected to navigate.

3.3 Shell plating and framing

3.3.1 The thickness of the shell plating in way of the ice belt is to be as required by Table 9.3.1 Ice strengthening.

Table 9.3.1 Ice strengthening

Item Parameter Requirements

(1) Shell plating and swim end plating (in way of ice belt)

Plating thickness ti = 1,5t r mm

(2) Intermediate ice frames

 Section modulus Zi = 0,75Z r cm3

(3) Side stringer

 Section modulus Zs = 2Z r cm3

(4) Bar stem

 Area A = 0,75L cm2

(5) Plate stem

 Thickness The greater of:

ts = 0,10L + 5 mm

ts = 12 mm

(6) Rudder stock and pintles

 Diameter δi = 1,15δr mm, see Note

(7) Rudder plating and webs

 Thickness tw = 1,25t rs mm

(8) Solepiece

 Transverse section modulus Zsp = 1,15Z rs cm3
Symbols
t i = thickness of shell plating in way of ice belt, in mm
t r = Rule thickness of shell plating, or swim end plating, in mm
t rs = Rule thickness of rudder plating or web plating, in mm
t s = thickness of plate stem in way of ice belt, in mm
t w = thickness of rudder plating or web plating, increased for navigation in ice, in mm
A = area of bar stem in way of ice belt, in cm2
L = length of ship, in metres, see Pt 3, Ch 1, 6.1 Principal particulars
Z i = section modulus of intermediate ice frames, in cm3
Z r = section modulus of the Rule main frames, in cm3
Z rs = Rule transverse section modulus of solepiece, in cm3
Z s = section modulus of side stringer in way of ice belt, in cm3
Z sp = transverse section modulus of solepiece increased for navigation in ice, in cm3
δi = diameter of rudder stock or pintle increased for navigation in ice, in mm
δr = Rule diameter of rudder stock or pintle, in mm

Note The gudgeons, rudder couplings and steering gear are to be based on the rudder stock diameter increased for navigation in ice.

3.3.2 Intermediate ice frames are to be fitted over the extent of the ice belt; and their scantlings are to comply with the requirements of Table 9.3.1 Ice strengthening. The ends of these frames may be sniped.

3.3.3 A side stringer is to be fitted over the longitudinal extent of the ice belt a position about half way between light and load waterlines and efficiently connected to frames and shell. The scantlings of this stringer are to be as required by Table 9.3.1 Ice strengthening.

3.4 Stem

3.4.1 A bar stem or plate stem is to comply with Table 9.3.1 Ice strengthening. Bar and plate stems, and their adjoining shell plating, are to be supported by horizontal webs, with a thickness equal to the shell plating in way, connected to the first frame, and spaced not more than 0,5 m apart. Furthermore, a centreline stiffener is required inside a plate stem. This centreline stiffener may be of the same scantlings as the fore peak frames.

3.5 Rudder and sternframe

3.5.1 The rudder stock diameter, pintle diameter and rudder plating and webs are to be as required by Table 9.3.1 Ice strengthening. The gudgeons, coupling, main piece and steering gear are to be based on the increased diameter of the rudder stock required for navigation in ice.

3.5.2 The solepiece section modulus for transverse bending is to be as required by Table 9.3.1 Ice strengthening.

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