Converted transport vessels can accommodate rigs, FPSO modules
“Our vessels have several big advantages over the converted tankers or bulk carriers,” says Kerssens. “First, we provide a totally unobstructed stern, unlike converted tankers which cannot roll on/roll off cargoes from the rear. Second, our vessels can berth at any shipyard, whereas others cannot as their hulls are too big. Third, we can have a huge amount of water above the deck, which means we can carry semisubs with their thrusters sticking out or jackups with large spud cans protruding. Only two other existing vessels can do that.”
Being self-propelled, Fairstar’s vessels can achieve a dry transport speed of 13 knots and a dry tow speed of 4 knots. In case of engine failure, both vessels also provide full redundancy in the form of three main engines and steerable thrusters, all supplied by Wartsila.
Generators power the hydraulic system for the ballast pumps and electrical equipment during submerging operations.
“Ballast control is provided by two rows of tanks and seven pumps,” says Kerssens. “The ballast control panel also overlooks the deck, which is handy because the operator can see the ship move as he presses the buttons.
“The pumps work with gravity as well as pressure, so they can serve the tanks in various ways. This is very sophisticated compared with converted tankers, which despite their newly built heavy-lift midship sections, the ballast tank arrangements can make ballasting and de-ballasting quite time-consuming. They cannot empty their tanks so delicately. We think we can adjust our operation better.”
Early in February, the Fjord underwent three days of tests in Malta on all aspects of its ballast system. These culminated in a complete submersion of the hull to a depth of 20 m (65.6 ft) below the water line, leaving around 11 m (36 ft) of water above the main deck, at an even keel. “We also found we could achieve 12 m (39 ft) of water at the stern, at a slight angle. This demonstrated that we could float onto the deck semisubs with their thrusters attached.”
Sea of Solutions performed basic design of both ships, while Babcock and Vuyk Engineering (now part of the IHC group) provided detailed design. The Fjord was lengthened by 12 m (39 ft) to give a better width/length ratio, Kerssens explains. Its main dimensions include an overall length of 159.24 m (522 ft), breadth of 45.5 m (149 ft), molded depth of 9 m (29.5 ft), and deadweight of 24,500 metric tons (27,006 tons). It provides a free deck space of 131.8 x 45.5 m (432 x 149 ft), and a deck load capacity of 25 metric tons (27.56 tons)/sq m (10.7 sq ft).
The Fjord can transport structures weighing up to 24,000 metric tons (26,455 tons), while the Fjell — being slightly smaller — has a maximum weight limit of 19,800 metric tons (21,825 tons). Fairstar expects the conversion process for the Fjell to be smoother, after the lessons learned from the previous program. The work has been entrusted to a less unionized part of Malta Shipyards.
C&M Group in Aberdeen awarded the contract for transportation of the Ice Maiden, which was brought to the UK for conversion into an Arctic DP-3 monohull flotel. “We thought we had a challenging conversion with the Fjord, but they had started this conversion in May 2006. The yard in Alabama had basically demolished the ship, but progress had been so slow that C&M decided it had to be moved to A&P Tyne.
Previous Page
|
Next Page
Page 2 of 3
Volume 68 Issue 8
August 2008
Add RSS Feed
