to ensure that they remained primed. They also should
be equipped with a strainer. Internal strainers are easily
serviced and are desirable; however, in the case of
stabilizer cooling systems, it’s also valuable to install an
external, forward-facing hull scoop strainer. This serves
two purposes. First, it prevents large debris from entering
the intake. Second, it maintains positive water pressure
on the intake, ensuring that it remains primed even in
heavy weather, when air frequently makes its way under
the hull. To the extent possible, the intake should be
located forward of the fins, since turbulence created by
fin actuation may increase the likelihood of air entering
Whichever cooling method is chosen, the heat
exchanger’s size is inversely related to the water flow.
High-volume pumps require smaller heat exchangers,
while smaller, lower volume pumps require additional
heat exchanger surface area and overall volume. These
components cannot be chosen independently.
Well-engineered, properly installed hydraulic systems
are known for their rugged reliability. In fact, in my
experience, there are but two primary causes for failures
in hydraulic systems such as those used in stabilizers.
The first involves improper installation or improper
specifications for components used in the system. As
mentioned above, this may include the size of the heat
exchanger, the size or location of the fins, or the location
of the seawater cooling intake. The second involves
a culprit that is responsible for the failure of many
lubricated systems, such as engines, transmissions, and
hydraulic systems: dirt. Real, honest-to-goodness dirt is
often silica or sand based, and it can be more abrasive
than broken hardened metal components. The results are
predictable: parts wear out and fail much more quickly
than they should. Fortunately, there’s not a lot of silica
floating around at sea or in the bilges of your boat. Dirt
in the generic sense, however, often includes pieces of
hose in chunk or dust form. This is much more common
and often finds its way into the system during assembly
or repair; thus, this type of dirt failure is completely
avoidable. Every hydraulic hose that’s cut and made up
for the system must be thoroughly cleaned by flushing
with fluid prior to installation.
The fluid inside the hydraulic stabilizer system should
be analyzed annually, along with the coolant and oil
from your engines, transmissions, and generators.
Through fluid analysis, potentially serious problems
such as water contamination or hydraulic pump wear
can be identified before a failure occurs. Most stabilizer
manufacturers provide recommended fluid replacement
intervals, typically every three years or after 2,000– 3,000
hours of use. (If your stabilizer system doesn’t include
an hour meter, one can be easily added, although most
recreational users never approach the hourly figure
before the three-year mark.) Keep a supply of
oil on board (the type varies from manufacturer to
manufacturer, from ISO 46 to 10w40) and a full
replacement quantity if you are cruising to remote
locations where it may be difficult to obtain.
Stabilizer hydraulic systems include spin-on filters,
which must also be replaced periodically, typically more
often than the oil. Most systems include an indicator
gauge that alerts the user as to when the filter requires
replacement. Continuing on the subject of lubrication,
nearly every stabilizer manufacturer offers clear details
about what components need to be externally lubricated
with grease or oil. Follow these guidelines to ensure
minimal wear and maximum reliability.
The stabilizer system’s heat exchanger, like any heat
exchanger, requires periodic inspection, cleaning, and
anode replacement. If a dedicated pump is used, it too
will require inspection and service from time to time.
Like running gear anodes, those used on fin shafts should
be inspected regularly and replaced when necessary.
The final component worthy of mention where
service and maintenance are concerned involves seals.
Most fin stabilizer manufacturers rely on a dual lip seal
arrangement that keeps sea water on the right side of the
hull. The seals do wear out and therefore must be
serviced. Typically, the interval is every two or three
years, and a haulout and fin removal are required. Most
stabilizers I encounter are well past due for this service,
and there’s a reason why. Most of the time, failing to
service the seals results in few obvious side effects.
Unfortunately, if the seals do leak, it leads to other costly
damage, like bearing corrosion and failure. At least one
seal manufacturer does not use ferrous bearings and thus
if the seal fails, it will not compromise this component.
A final note on service: If your fins utilize a locking pin
arrangement (a pin that is manually inserted into a set of
holes to immobilize the fin for repair or haulout), never
place your finger or anything else you value into that
hole. It’s designed to accept the pin alone. The slightest
movement of the fin could result in injury or amputation.
Fin stabilizer systems fall squarely into the category of
tried and proven marine equipment. They’ve been
serving boat owners and crews admirably for decades,
and it’s likely they will continue to do so for years to
come. Select your system wisely, be sure that it’s
properly installed, and provide it with the necessary
maintenance, and it will make life at sea more enjoyable.
It may even save you a few dollars at the fuel dock.