Visitors to the recent ITS 2014 Convention in Hamburg were
treated to demonstration trips and a close inspection of the tug. With the
exception of the hybrid propulsion system and some customisation required by
the owner, this tug is very little different to the standard diesel powered ASD
2810, of which over 170 have been sold around the world. Bernardus measures 28.67m in length overall with a maximum beam of
10.43m, a depth of 4.38m and draft aft of 5.15m. The design and construction
meets the requirements of Lloyds Register +100 A1 Escort Tug(*)LMC UMS IWS for
use under the Dutch flag.
Bernardus is powered by a ‘diesel
direct – diesel electric- battery’ hybrid propulsion system enabling the tug-master
to choose the mode of operation depending on the task in hand. At the heart of
this propulsion system is a pair of MTU 16v4000M63R diesel main engines capable
of generating a total of 3680 bkW (4936 bhp) at 1600 rev/min. Each main engine
is coupled to a Rolls Royce US 205 fully azimuthing propulsion unit.
Located in each shaft-line is an ABB M3LP459 250 bkW, water-cooled, electric motor/generator incorporating a main shaft capable
of transmitting the main engine’s full torque to the propulsion unit. This
arrangement enables the main engines to drive the propulsion units when high
power settings are needed, or the units to be powered by the motors using
current from the batteries or the main generator when less power is required.
A third MTU diesel, a 12v 2000 M41B, powers the main propulsion
generator rated at 800kVA 400v 60Hz to supply power for propulsion and battery
charging. When required this engine also powers a Jason 250x350 OGF centrifugal
fire pump delivering a maximum of 1200 cu/m/min of water to a pair of short
barrel monitors mounted forward of the wheelhouse. All three MTU engines are
fitted with: diesel oxidation catalyst (DOC) + diesel particulate filtration
(DPF) + selective catalytic reduction (SCR) exhaust gas treatment systems
meeting Tier III requirements.
The choice of MTU diesel engines in the new hybrid vessel is
significant. Bernardus is the first
Damen built tug to use MTU equipment but Damen is working closely with MTU on
engines for use in tugs and other vessels, including the possibility of using
an LNG fuelled variant at some time in the future.
Also located in the engineroom is a single Caterpillar
powered C4.4 generator for emergency and ‘stand-by’ use, rated 107 kVA at
230/400V–50 Hz, to supply the vessel systems and domestic loads.
Another critical component of the ‘hybrid’ propulsion system are
two Valence Lithium-Ion battery-pack each with a capacity of 120 kWh. The
batteries are housed in an air-conditioned compartment and can be charged by the
MTU diesel generator, the motor/generators in the shaft-line when the main
engines are running, or from shore power when alongside.
The tugmaster can choose the best mode of propulsion for the
task in hand by means of a simple ‘four-position’ selector switch marked;
Harbour – Free Sailing – Towing -- FiFi
(fire-fighting). This system results in a significant reduction in fuel
consumption of 10-30% and 20-60% lower emissions. The battery system makes it
possible to maintain position, manoeuvre travel at low speed between
assignments with the diesel engines closed down. When in fire-fighting mode the
main engines will start for position keeping.
On trials the tug could sail at 4 knots on batteries for up
to 1 hour and a speed of 8.5 knots was attained with only the MTU generator in
operation. With the main engines running in the normal way a free running speed
of 13.4 knots was achieved ahead and 13.0 knots astern. A maximum bollard pull
of 60.2 tonnes was recorded towing ahead and 55.3 tonnes astern, comparing
favourably with conventional ‘all diesel’ ASD 2810 tugs
Solar panels fitted to the deckhouse charge 24V batteries
supplying emergency power for radios, navigation lights and other essential
carried out for Iskes, includes the installation of double drum towing winches
fore and aft, timber protection on the after deck (for anchorhandling), an open
stern with MKB-86 tonnes SWL towing pins and chain stopper forks. A novel
feature is a removable aft bulwark to give a dry after deck during shiphandling
operations. When the tug is required for anchorhandling the bulwark can be
lifted out, exposing the stern roller.
towing winches are electrically powered two-speed machines with a maximum brake
holding load of 150 tonnes. The forward winch is equipped for shiphandling over
the bow and incorporates a windlass for the tug’s anchors. The aft winch is
equipped with spooling gear and configured for anchorhandling and towing over
The wheelhouse is of the
familiar Damen design with good all round vision. A normal inventory of
controls and instruments for the propulsion system and winches is supplemented
only by a few additional items required for the hybrid functions.
Fully air-conditioned accommodation
fitted out to a high standard is provided for up to seven persons, in single
cabins for the captain and chief engineer, one single and two double-berth
cabins. All of the normal facilities include a mess/day room, galley, dry store
and sanitary spaces.
Damen Shipyards have already
taken orders for three ASD 2810 Hybrids for the Dutch Navy and have plans to
build further examples for ‘stock’.
By Jack Gaston