Figure 3. Design evolution of Russian polar icebreakers (after Brigham 1991).
cessful "spoon-shaped" bow was first proposed
Recent history
Figure 2 shows a summary of significant ad-
and built by Ferdinand Steinhaus of Hamburg in
vances in the polar ship technology during the past
1871. In 1892, Weedermann invented and patented
four decades, as outlined by Brigham (1987), made
a device to be placed in front of a ship having a
by Finland and the former Soviet Union, and by
bow not suitable for icebreaking on its own. These
the U.S., Canada, Germany and Japan. Together, Fin-
devices are still used on Dutch rivers and canals.
land and the Soviet Union have made enormous
By 1900, it was well understood that, while ships
contributions to the development of polar ships.
with blunt bows are efficient in breaking level ice
The Soviet Union first used nuclear technology
in sheltered areas, such as rivers, lakes and other
to power the icebreaker Lenin, which was built in
protected areas, their performance in rubble ice is
1959 with a propulsive power of 29 MW (39,000
poor because they have a tendency to push bro-
hp). The Finnish shipbuilder, Wrtsil Shipyard
ken ice ahead of themselves. On the other hand,
(now Kvrner Masa-Yards), built many icebreak-
ships with wedge-shaped bows and sharp stems
ers for the Soviet Union and created extensive de-
did not have any tendency to push rubble ice. This
sign evolution during the years of the development
experience led to all sea-going ships built between
of conventionally powered icebreakers. Recently,
1901 and 1979 having a wedged-shaped bow and
these two technologies have merged, as shown in
a sharp stem (Johansson et al. 1994). Over the years,
Figure 3, to develop the Taymyr-class (Fig. 4), shal-
the wedge-shaped bows became known as "con-
low-draft polar icebreakers built in Helsinki with
ventional" bows, and the other shapes as "uncon-
Soviet nuclear propulsion systems installed in St.
ventional" bows.
Petersburg.
The development of the bow form remained
Similarly, developments in the U.S. and Canada
stagnant in the early and middle part of the 20th
have contributed to changes in key areas of ice-
century (Johansson et al. 1994). This can be attrib-
breaking technology (e.g., hull and bow form, gas
uted partly to other priorities caused by the two
turbines, and controllable-pitch propellers). In
World Wars and by the slowdown of economic
1969, the U.S. modified tanker Manhattan had ten-
acivity during the large-scale recession of the 1930s.
fold the displacement of earlier icebreakers, giv-
Despite this stagnancy in bow design, other inno-
ing her great ramming capability. In the early
vations were introduced during this time. The Rus-
1980's, modern hull and propulsion technologies
sian icebreaker Yermak, built in 1899 and fitted
were also applied to Antarctic ships (e.g., Japan's
with propulsive machinery of 7.46 MW (10,000
Shirase, and Germany's Polarstern). The bows of
hp), had considerable effect on the icebreaking
three icebreakers were converted to the newly de-
technology at the turn of this century by becom-
veloped Thyssen-Waas bow: Max Waldeck in 1980,
ing a pioneer in many untested offshore areas. In
Mudyug in 1986 and Kapitan Sorokin in 1991. The
1933, diesel-electric propulsion was introduced on
results of full-scale trials in open water and in ice
the Swedish icebreaker Ymer. In 1947, twin bow
indicate that this change in the bow of Mudyug
propellers were introduced on the Canadian ice-
has increased her icebreaking capability in level
breaking ferry Abgeweit. (However, the use of
ice at reduced power requirements (Milano 1987).
bow propellers has now been discontinued be-
However, there were problems with wave slam-
cause of their interference with ice.)
5
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