PLAIN SAILING: COOL SOLUTION TO NAVY OVERHEATING PROBLEM
More than $250,000 in annual fuel savings for two of the Royal New Zealand Navy’s (RNZN) fleet
will be possible, thanks to a unique engineering solution developed by the RNZN and its fleet
Offshore patrol vessels HMNZS
Otago and HMNZS Wellington
were designed to run mostly
using just one of their two
main engines and propeller shafts.
The speed generated by one
engine is generally enough for their
operational requirements.
But the issue with this, RNZN
Logistics Commander Maritime
Captain Andrew Nuttall says, was
that the trailing shaft, even though
not powered by an engine, still
turned because of the wind-milling
effect of the propeller through
HMNZS Otago
the water, which subsequently
generated heat in the gearbox.
“The pump to supply coolant to
remove the heat was driven by
the engine,” Captain Nuttall says.
“But because this was shut down
in the case of the trailing shaft, the
result was that various components
began overheating.
“To avoid that, both engines were
required to be running most of the
time, even though only one was
technically required to power the
vessel.”
This meant that $200,000 of
essentially wasted fuel was
required for every 1,000 hours
of running. Having both engines
operational also required increased
maintenance and It also meant
that marine technicians had to
manually adjust the cooling system
at all hours of the day and night to
ensure the ship’s safety.
The RNZN and Babcock combined
engineering design team
developed a unique solution that
cross-connected the cooling
system, so that when an engine
was shut down the propeller could
still rotate, while the heat generated
was cooled through diversion of
coolant.
The solution developed by the team
would result in significant financial
benefits, Captain Nuttall says.
“The saving in fuel alone is
impressive. Combine that with
the reduced maintenance costs
and this solution represents an
excellent example of the value our
engineering team can add.”
maintenance partner Babcock (NZ).
PREVENTATIVE MAINTENANCE