Quarterly December 2011 - Odfjell

NR.04/ 11
7
Picking the low hanging fruits:
– New hull cleaning and propeller polishing schemes
give important fuel and emission savings
By Svend Foyn-Bruun and Erik Hjortland
Equipment for hull cleaning
The recent trial of a new hull cleaning and
propeller polishing scheme on a ship has
showed very promising results. The fuel efficiency
increased significantly compared to
previous measurements.
Although hull cleaning and propeller
polishing are normal part of ordinary drydocking
work, the remarkable result may
lead to a new practice by which all our ships,
both time chartered and owned, will be more
closely monitored and the cleaning intervals
shortened.
Fuel and emission savings
We estimate that on this particular trial ship,
the new and advanced hull cleaning and
propeller polishing scheme will reduce the
CO 2
emissions by 5,000 mt in one year.
It would be hard to make an individual underwater
cleaning programme for each ship, but
a scheme that introduces a shorter interval
compared to todays practice combined with
a closer performance evaluation seem to be
optimal both from an environmental and a
financial viewpoint.
New techniques
The underwater hull cleaning and propeller
techniques have improved over the last
couple of years. Today it is possible to carry
out the cleaning during a normal port stay
without arranging for the vessel to be off hire.
The ‘robotized’ hull cleaning may take place
at anchorage or at cargo berths without any
significant release of antifouling residues.
The whole operation can be completed within
12 hours. The result is a significant reduction
of consumption and emissions of CO 2
, NOx
and SOx.
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