Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Ships, July 2022 - Part 8 Rules for
Ice and Cold Operations - Chapter 2 Ice Operations - Ice Class - Section 9 Machinery requirements for first-year ice conditions
- Ice classes 1AS FS(+), IAS FS, 1A FS(+), 1A FS, 1B FS(+), 1B FS, 1C FS(+) and 1C FS
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Section
9 Machinery requirements for first-year ice conditions - Ice classes
1AS FS(+), IAS FS, 1A FS(+), 1A FS, 1B FS(+), 1B FS, 1C FS(+) and 1C FS
9.1 Powering of ice strengthened ships
9.1.1 For
ships that require additional strengthening in ice, the total shaft
power installed is to be calculated using the following Sections,
but is not to be less than required by the Finnish-Swedish Ice
Class Rules in force at the time of contract.
9.1.2 Ice
strengthened ships which are to be considered to have an icebreaking
capability are to be able to develop sufficient thrust to permit continuous
mode icebreaking at a speed of at least five knots in ice having a
thickness equal to the nominal value for the desired Ice Class and
a snow cover of at least 0,3 m.
9.1.3 The
shaft power necessary to provide an icebreaking capability can be
determined by the equation:
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P
1
|
= |
 kW
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where
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Δ |
= |
displacement,
in tonnes, see Pt 3, Ch 9,7.2.1
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C
1
|
= |
 |
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C
2
|
= |
0,9 if the ship is fitted with a controllable pitch propeller,
otherwise 1,0 |
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C
3
|
= |
0,9 if the rake of the stem is 45° or less, otherwise 1,0.
The product C2 C3 is not to be taken as less
than 0,85
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C
4
|
= |
1,1 if the ship is fitted with a bulbous bow, otherwise 1,0 |
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h
|
= |
ice
thickness |
| = |
1,0 for Ice Class 1AS FS(+)
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| = |
0,8 for Ice Class 1A FS(+)
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| = |
0,6 for Ice Class 1B FS(+)
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| = |
0,4 for Ice Class 1C FS(+)
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S
c
|
= |
depth of snow cover |
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v
|
= |
ship
speed, in knots, when breaking ice of thickness h.
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9.2 Materials for shafting
9.2.1 For screwshafts in ships intended for the following notations: Ice Class
1AS FS(+) IAS FS, 1A FS(+), 1A FS, 1B FS(+), 1B FS, 1C FS(+), 1C FS; and where
the connection between the propeller and the screwshaft is by means of a key, Charpy
impact tests are to be made in accordance with the requirements of the Rules for the
Manufacture, Testing and Certification of Materials, Ch 5, 3.4
Table 5.3.2 Mechanical properties for acceptance purposes: carbon, carbon-manganese and
alloy steel forgings for machinery and shafting.
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