Page 49 - Ship Construction.DJ Eyres 6Ed

Ch04-H8070.fm Page 38 Wednesday, October 18, 2006 6:52 AM
38 Ship Construction
and for operation in multi-year ice. First year ice notations are for addi-
tional strengthening where waters ice up in winter only and multi-year ice
for service in Artic and Antarctic waters.
The increasing maritime trading within Arctic waters in the past decade and
the desire to ship oil, gas and other commodities from there all year round
appears to have resulted in the class societies adopting to some extent the ice
strengthening requirements of the “Finnish-Swedish Ice Class Rules 1985”
--- ใช้เพื่อการศึกษาเท่านั้น---
developed for vessels trading in winter and for which the keel was laid after
1 November 1986. These requirements intended primarily for vessels operating
in the Northern Baltic in winter are given for four different ice classes.
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
Ice Class 1AA
Ice Class 1A
Ice Class 1B
Ice Class 1C

The hull scantling requirements determined under these rules are based
on certain assumptions concerning the nature of the ice load the ship’s
structure may be subjected to. These assumptions having been determined
from full scale observations made in the Northern Baltic.
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This increased trading in Artic waters has also created particular interest
in the establishment of universal requirements for ships operating in ice.
Both IMO and IACS have been involved in this work with IMO produc-
ing guidelines in December 2002 for ships operating in Arctic ice-covered
waters for which they prescribe seven ‘Polar Class’ descriptions. These
range from PC 1 for year -round operation in all Arctic ice covered waters
to PC 7 for summer/autumn operation in thin first-year ice which may
include old ice inclusions. Subsequently IACS set up a working group to
develop Unified Requirements for Polar Ships that would cover –

(a) Polar class descriptions and applications;
(b) Structural requirements for Polar class ships
(c) Machinery requirements for Polar class ships

It was intended that with the completion of these Uniform Requirements
for Polar Ships and their adoption by the IACS Council the IACS member
societies will have one year in which to implement these common standards
for ships operating in ice.

Structural Design Programs

In recent years the principal classification societies have developed software
packages for use by shipyards which incorporate dynamic-based criteria for the