Reference Story
fjord – a barge converted into
a self-powered vessel
Vacon AC drives control 4.5-MW main propulsion
Time is money, also at sea, so the demand for rapid, heavy,
long-distance shipping transport is growing. For this reason,
Fairstar* decided to convert Fjord, a former barge, into a
semi-submersible heavy transport vessel with propulsion
of its own. In cooperation with Imtech Marine & Offshore**,
Vacon has supplied AC drives to control the 4.5-MW main
propulsion.
Self-propelled vessels are faster and operationally more
flexible than barges reliant on tugs. The average transit speed
of a ship is 12-14 knots versus 4-7 knots for a towed barge.
“Semi-submersible loading ships with their own forward
propulsion are more manoeuvrable and flexible and can be
deployed without tugboats,” explains Cor van Miltenburg,
Business Unit Director, Special Vessels & Offshore at Imtech
Marine & Offshore, Vacon’s system integrator partner since
2002.
The Fjord will primarily be employed to transport offshore
equipment such as jack-up and semi-submersible drilling
rigs and floating production units for the offshore oil and
gas industry. With a semi-submersible vessel, the cargo is
loaded and unloaded while the vessel is ballasted down and
semi-submerged. The cargo is then floated on and off the
vessel’s large open cargo deck. Equipped with one of the
most sophisticated ballast control and loading systems in the
world, the Fjord is capable of carrying 20,000-25,000-tonne
loads.
Consortium responsible for total solution
The conversion of the Fjord was carried out by a consortium
comprising Imtech Marine & Offshore, Radio Holland (also
part of Imtech) and Wärtsilä. Together these three parties
provided the total solution for all the electro-technical
components and the diesel-electric propulsion, including
power generation, an integrated bridge, and all the navigation
and communication equipment on board.
Imtech was responsible for project management, engineering
and delivery of the main electrical equipment, and for
commissioning the electrical systems on the vessel. Imtech
delivered the two 4500-kW variable speed drive systems for
the steerable thrusters fitted with a fixed-pitch propeller.
Wärtsilä delivered three diesel generating sets, with a
maximum continuous power output of 3840 kW at 720 rpm, to
supply electrical power. Wärtsilä also supplied the 1500-kW
bow thruster.
Vacon DriveSynch for redundancy at sea
As Imtech’s partner, Vacon supplied the AC drives needed for
the diesel-electric propulsion. The 4.5 MW main propulsion
system of the Fjord uses Vacon DriveSynch, a new control
concept for paralleling high-power liquid-cooled Vacon AC
drives. Vacon DriveSynch allows a motor to be controlled
by two to four power units each of 100 – 1500 kW. The Vacon
DriveSynch is suitable for controlling single- and multiwinding AC motors. Vacon DriveSynch is especially suitable
for marine and offshore applications, providing a high degree
of redundancy and system safety.
Christening with holy water and champagne
For the conversion, the Fjord was in dry dock at Malta
Shipyards located on beautiful Malta in the heart of the
Mediterranean. The christening took place in Malta in August
2007 in accordance with local traditions. The Fjord was
christened both by the archbishop of Malta and subsequently,
in a more profane manner, with champagne. Ship christening
is one of the few rites still in use today that have a tradition
going back some 4,000 years.
Thorough sea trials a complete success
The conversion, including an extension by 20 meters, was
almost as extensive as a new construction project. Careful,
precise testing was needed before the Fjord was ready to enter
into service. In December 2007 – January 2008, three days of
extensive sea trials were carried out to test all aspects of the
Fjord’s ballast system, culminating in a complete submersion
of the vessel’s hull to a depth of approximately 20 metres
below the surface, giving about 11 metres of water above the
main deck.
“The submersion test was a complete success. All systems
were checked by our technical team and were put to a
rigorous inspection before, during and after the submersion.
The submersion was smooth, controlled, and the stability
profile of the Fjord was exceptional. We are very pleased with
the vessel’s performance,” says Dave Hangoor, Operations
Manager, Fairstar.
Sister vessel to follow
The experience gained in the conversion process of the Fjord
will be of great benefit in the current project, the conversion
of Fjell, the Fjord’s sister vessel. Overall the work is similar
to that carried out on the Fjord, with the exception that no
lengthening is required. As on the Fjord, Vacon AC drives will
control the main propulsion on the Fjell.
The Fjord during submersion off the coast of Malta. After
a 20-metre lengthening, the Fjord is 164.3 m between
perpendiculars, with a breadth of 45.5 m and depth of 9
m. The Fjell is slightly smaller.
The Fjord at the sea. Originally the Fjord and the Fjell were
semi-submersible barges. After conversion, these selfpropelled heavy-lift transport vessels will be primarily
employed in the transport of offshore equipment such as
jack-up and semi-submersible drilling rigs and floating
production units for the offshore oil and gas industry,
worldwide.
Photos: Courtesy of Fairstar and Imtech.
* Fairstar Heavy Transport NV (formerly Fairmount Heavy
Transport) was founded in 2005 to be the partner of choice for
clients seeking high-end ocean transportation services for
the largest floating and non-floating cargoes.
** Imtech Marine & Offshore is the one-stop shop for
electrical, platform and integrated bridge automation, HVAC,
and electrical propulsion technology for naval vessels,
commercial ships and working platforms.
Tel. +358 (0)201 2121
Fax +358 (0)201 212 205
www.vacon.com
[email protected]
RS00088A
Vacon Group
Runsorintie 7, 65380 Vaasa, Finland