HANSA 03-2018

Schiffstechnik | Ship Technology
»Dynamic Biofilm
Protection« for more
propeller efficiency
When confronted with marine growth, a propeller’s
efficiency can drop considerably. In order to avoid
the formation of biofilm, German Hasytec Group
has developed a »Dynamic Biofilm Protection«
system
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It is a marine growth preventing
system developed and produced
in Germany which avoids the formation
of biofilm, the initial step
of all kinds of marine growth and
fouling.
The efficiency of a vessel’s propeller
which is confronted with a layer
of marine growth drops by 1,5%
up to 5% after approximately six
months, even if the vessel is operated
and not being laid up for a longer
period. As a result, fuel consumption
is increased, leading to a higher
impact on the environment. Hasytec
designed its system to protect
liquid carrying surfaces against biofilm
and therefore against marine
growth and fouling.
Biofilm does not occur during operation
of the propeller. »When the
propeller is not in operation as for
example at anchorage, in port or
during being idle for any reason,
the biofilm starts building up immediately
after seconds,« the company’s
experts say. After a short period
of time, the biofilm layer shows
a thickness which can’t be wiped off
anymore through propeller operation
only. Divers’ cleaning operation
becomes necessary after a while.
Hasytec relies on the ultrasonic
based »Hasytec BDP«, which emits
ultrasonic waves carried throughout
the stern tube sealing into the
prop shaft and along this way into
the prop blades. On the blades and
even on the rope guard the ultrasound
is transmitted to prevent biofilm
in its initial steps, keeping the
surfaces free of fouling and marine
growth permanently.
The transducers are installed in
a circular arrangement on the forward
stern tube sealing. Same as
on all other DBP installations, the
transducers are glued metal to metal
and get connected with high quality
plugs and protected, shielded cables
to the modular control unit.
To ease the operation, the system
can and shall be switched on permanently.
According to the developer,
the DBP has already proved its efficiency
in 2017 on different kinds
of vessels. »By using DBP, propeller
cleaning isn’t required anymore and
the vessel’s fuel consumption is not
impacted by the propeller on a general
base,« it is said, adding »as the
costs for an installation are very reasonable,
the return will be after six to
twelve months.«ED
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The pictures show the comparison of a Suezmax Tanker’s 8,5 m diameter propeller
Without DBP it had to be cleaned by divers approx. every six months
Pictures 1–3 show the usual situation after six months
»With DBP the propeller is as clean as directly after leaving dry dock, even during the
tip«, Hasytec emphasizes. Propeller maker’s stamp clearly visible
Pictures 4–5 show it after seven months
Pictures 6–8: Installation of DBP transducers on forward stern tube sealing
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Photos: Hasytec
HANSA International Maritime Journal – 155. Jahrgang – 2018 – Nr. 3 71