the next century. The ship will have an overall
for the Northwest Passage is slightly bigger in size
length of 103.6 m, waterline length of 93.9 m, maxi-
and displacement than Yamal, but the designed in-
mum beam of 27.1 m, depth of 12.2 m, draft of 9.1
stalled power (from diesel engines with a mechani-
m and a displacement of 11,684 tons. The vessel
cal transmission to two controllable-pitch propel-
will have a flat bow with a ridge in the middle to
lers in nozzles) is less than that of Yamal, which is
break ice in bending and to clear it on the side,
equipped with three propellers driven by nuclear
and a double hull to comply with the CASPPR
power through an electrical transmission. Auxil-
guidelines. The propulsion system will include die-
iary systems for the Northwest Passage icebreaker
sel engines of 15 MW (20,000 hp) and two-ducted
include water wash and heeling tanks, as well as a
4.1-m-diameter controllable-pitch propellers.
stainless steel belt with Inerta coating elsewhere.
As mentioned earlier, it is well within known
Figure 25 is a sketch of an "iceraker," as pro-
and proven technology and experience to design,
posed by Johansson et al. (1994). The proposed
build and operate an icebreaker year-round inde-
iceraker has a vertical-sided, 50-m-wide hull that
pendently in the Arctic. Keinonen (1994) has set
also has a submerged cantilever in front of and on
down the performance criteria of a proposed ice-
each side of the vertical, wedge-shaped bow. At
breaker for the Northwest Passage, as given in
the edge of this cantilever, air is introduced into
Table 4. The design parameters of the icebreaker
the water at a depth of about 15 m. Seven spurs
are given in Table 5, in which the values of those
are located on top of the cantilever at a transverse
parameters for Yamal are also given for compari-
spacing of about 20 m. The spurs create a 120-m-
son. It can be seen that the icebreaker proposed
wide channel of broken ice by deflecting a floating
Table 4. Performance criteria for a Northwest Passage icebreaker (after Keinonen 1994).
Performance
Criteria/measure
Requirements
Level ice
2 knots at continuous speed
3m
Multi-year ice
Thickest broken ice on first ram
8m
Backing
Thickest level ice ice broken in a continuous motion
2m
Thickest ice below which turning circle is smaller than 10Lwl
Turning
2m
Extraction
Wind speed in which able to extract (also needs to be able to
15.4 m/s
extract after any ram)
(30 knots)
Table 5. Comparison of design parameters of proposed Northwest Passage icebreaker (Keinonen 1994) with
those of the Russian icebreaker Yamal.
Proposed values for a
Northwest Passage
Values for the Russian
Parameter
Unit
icebreaker
icebreaker Yamal
Displacement
ton
30,000
23,460
Water line length
m
140
136
Length of parallel mid body
m
70
no data
Beam at water line
m
30
28
Draft
m
14
11
Hull design concept
type
four-section bow
conventional, straight
wedge shaped, double
Stem/buttock angle
degrees
17
17
Flare/frame opening angle
degrees
60
--
Shaft power
MW
40
56
Propellers
number/type
2CP in nozzles
3FP
Drive system
engine/transmission
diesel/mechanical
nuclear/steam turbine/
electrical
Reamers
type--width m
two way--2 m
none
Appendages
names
stern pods, shilling
ice horn
rudders, bottom wedge
Auxiliary systems
types
water wash, heeling
air bubbler
Hull coating
types
Stainless and Inerta
polymer coating
coating with cathodic
protection
29
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