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Arctic patrol ship could have double-
acting hullform
Canada’s proposed Arctic Offshore Patrol Ship (AOPS) could be the first
warship to be built with an icebreaking double-acting hullform of the type
successfully pioneered by STX Europe’s Aker Arctic.
peaking at an industry day event
towards the end of 2008, Dan
McGreer, Principal Engineer at
STX Canada Marine Inc provided an
update on the AOPS programme, and
an overview of the key elements of
the programme, including: the main
particulars; hullform; propulsion
machinery ; general arrangement
arrangements for landing craft and
boarding boat; aviation facilities; and
key mission systems.
One of the most interesting features
being examined in the current phase of
the programme, design definition, is the
use of a double-acting hullform, which,
if adopted, would make the icebreaking
AOPS the first warship with such
a hullform.
Simply put, when transiting waters AOPS could be the first warship with the double-acting hullform first developed by STX
with heavy ice conditions, a vessel Europe (Aker Arctic).
with a double-acting hullform moves
stern-first, to break its way through
ice; when returning to light ice main way of operating in heavy ice The other advantage of adopting
conditions or open waters, the vessel conditions have been pioneered by the double-acting hullform is that,
turns through 180 degrees and sails Aker Arctic in Finland (now part of traditionally, icebreaking vessels have
conventionally, bow-first. STX Europe). been quite poor in open water, typically
Most conventional icebreakers have The key to this development is the use having a total efficiency some 20-40%
had reasonable capability to run astern of azimuthing podded propulsors, which less than a good open water vessel.
in ice, even if not designed specifically gives a vessel the benefits of electric This has been mainly due to the bow
to do so. However, over the last decade propulsion and excellent manoeuvrability. forms, which have been developed
hullforms and propulsors that work In the double-acting hullform, these are to break thicker and thicker ice, and
together to make running astern the combined for the first time. icebreakers’ open water characteristics
have thus suffered.
Some icebreakers with bow-mounted
The double-acting
propellers have been developed,
hullform proposed
mainly for operation in the Baltic, but
for AOPS makes
experience with Arctic icebreakers has
use of azimuthing
reinforced the view that performance
propulsors, such
in severe ice tends to be better when
as the Azipod,
running astern. With the development
shown here.
in the last decade of electrically
driven podded propulsion devices,
such as the Azipod, and full-scale
testing and construction of a range
12 Warship Technology March 2009
WT_Mar09_p12+13+14.indd 12 3/5/09 5:21:21 PM
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