Fin Stabilizers
Courtesy of Arcturus Marine
There are a number of hydraulic system plumbing options that may be used for most fin stabilizer installations. Many twin- screw
vessels take advantage of the redundancy offered by dual-pump installations.
FIN STABILIZERS: HOW THEY WORK
Active fin stabilization has been around for many years,
with the first military and commercial systems seeing
action as early as the 1920s. There is an advantage to
using a tried and true concept: most of the faults and
bugs have been worked out, leaving room for innovation
and for fine-tuning an already viable idea. Today, fin
stabilizers are used on everything from recreational
vessels as small as 30 feet to commercial vessels of 350
feet or more. The icebreaker I cruised to Antarctica in
2002 while on assignment for PMM (see “The Mother of
All Passages,” June ’03) was equipped with retractable fin
stabilizers, which enabled it to navigate among icebergs
without fear of damaging the fins. Although the run
between the Falkland Islands and the Antarctic continent
was anything but smooth, the stabilizers reduced the
ship’s roll and improved her seakeeping characteristics as
she transited the storm-tossed waters of Drake Passage.
Every vessel has a roll period, or roll frequency, defined
as the time it takes to roll from starboard to port and
back again. When the wave period (the time it takes
for a wave to pass, from crest to crest) approaches or
equals a vessel’s roll period, the rolling motion of the
vessel will increase, often to sickening levels.
Although the exact details of how a particular
manufacturer’s fin stabilization system operates may vary,
what follows is an overview of how fins work to mitigate
undesirable vessel movement. Typically, two fins—one on
