Feature 2 | Diesel anD Gas technoloGy
Composite shafts press their case
Growing demand for carbon fibre drive shafts for ship and boat propulsion.
W
eight-saving composite the company says.
m at e r i a l s b e c a m e a CENTA points out that carbon fibre
commonplace feature of civil is around 70% lighter than conventional
aviation in the early 1980s. Since that time, steel, while the material also exhibits a
such materials have also been gaining long service life, extremely low thermal
ground in maritime applications, with the expansion, and excellent noise damping
need to increase vessel speeds by reducing characteristics.
their weight especially coming to the fore Moreover, composites allow longer
in the case of high-speed ferries. spans without additional intermediate
Endurance, stability, and low weight: shaft bearings. This, the company argues, CENTADISC carbon fibre shaft for the
these are all features which have rendered in turn, implies further weight savings, vessel Flying Cat.
carbon fibre applications interesting for reduced costs, less assembly work and
marine propulsion, according to a leading maintenance, and a further reduction of
supplier of drive components. noise and energy loss. experiences CENTA has obtained with
CENTA, of Haan (near Düsseldorf, Composite sections of up to 12m or more carbon fibre as composite material speak
Germany), reckons to have been one are possible and, by combining sections, for themselves: more than 150 ships have
of the pioneers among those using no limit has thus far been established to been equipped with carbon fibre shafts
composites for drive shafts, with research overall shaft lengths. Applicable torques during the last 10 years. Every single one
and development starting 12 years ago of 1000kNm have already been delivered, of them is working reliably. Market prices
in cooperation with the Technische while those of up to 2200kNm have been for the composite shafts are still higher
Universität Darmstadt (Germany) and designed. The biggest shaft ever supplied than those for steel, but including the
classification societies. by CENTA transmits 23MW from a gas overall service life of the shafts into the
Today the company’s portfolio includes turbine to a waterjet. cost-effectiveness evaluation quickly puts
over 20 elastic couplings, drive shafts, and The latest development from the things into perspective. The shafts show no
supplementary products, covering a torque company sees the introduction of the signs of material fatigue or corrosion, and
range of 1kNm up to 650kNm. Among ‘CENTADISC-C’ – a flexible shaft, they work maintenance-free. Furthermore,
these are drive shafts with a capacity of consisting of fibre-reinforced composite their lightweight construction meets
more than 25MW per shaft, while 600 of membranes and composite hollow the demands for greater velocities and
these shafts are already in service. shafts. Areas of application include: ship fuel economy. Comfort aboard a ship is
According to CENTA, demand for propulsion (namely waterjets), wind significantly increased by shafts running
composite drive shafts is constantly power plants, cooling towers, and general smoothly and evenly. Thus, it is merely
growing. ‘More and more high-speed engineering. The unit is extremely low in a matter of time before carbon fibres
ferries, cruise vessels, luxury yachts, weight, maintenance-free, and applicable will play as essential a role in maritime
tug boats, and rescue boats are being to torque ranges of up to 20kNm. applications as they are currently playing
equipped with lightweight shaft solutions’, According to the company: ‘The good in civil aviation.’ NA
Typical arrangement of CENTA couplings and carbon fibre shafts. The first sections behind the engines also comprise two CENTAX
torsional couplings each that tune the torsional vibrations of the system.
58 The Naval Architect March 2008
NA Mar 08 -
p58.indd 58 10/03/2008 12:04:40
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