Some 50,000 islands and thousands of narrow fjords cut into the mountainous countryside along Norway’s jagged coastline. Diesel-fueled ferries have transported people and goods between the islands and across the fjords for decades, but a new fleet of natural gas-powered ferries is now improving mobility without emitting noxious fumes that pollute the marine environment.
Designed by LMG Marin AS of Bergen, Norway, and built by Aker Yards ASA at two of its world-famous shipyards, the five ferries are powered by Rolls-Royce engines that use liquid natural gas (LNG). Norwegian authorities decided to build the LNG-fueled ferries following the success of the world’s first ferry to run on natural gas: prototype vessel “Glutra,” which began service in January 2000. LNG is an attractive alternative fuel not only because it is relatively clean, but also because Norway has an ample supply.
{sidebar id=273 align=right} The gas is transported as a liquid, then warmed and evaporated before being fed into the engines. The fuel burns cleaner than diesel — reducing CO2 emissions by about 20 percent, NOx emissions by about 90 percent, and sulphur oxide emissions by nearly 100 percent, according to Rolls-Royce plc. Though a major exporter of natural gas, Norway has a relatively low domestic consumption rate. Officials note that an LNG-fueled fleet will consume enough gas to justify building out the country’s natural gas distribution infrastructure.
With experience designing more than 1,000 vessels of various types, LMG Marin easily met the unique design specifications for the ferries. Each 129-meter-long-vessel is doubled-ended, with one enclosed and one open vehicle deck shielded by high sides and bow visors, and passenger decks and wheelhouse located amid ships. Each vessel can carry about 212 cars and 584 passengers.
The ferries operate at various service speeds depending upon their departure frequencies and total transport capacities. Three vessels on a busy service route south of Bergen operate at 21 knots; the other two vessels on a service route farther south operate at 17 knots. Owned and operated by the transportation group Fjord1, the fleet represents a $235 million investment.
{sidebar id=274 align=right}LMG Marin engaged about 20 engineers in the design project, which was commissioned in December 2004. To prepare detailed production design drawings as quickly as possible, LMG Marin deployed MicroStation and AutoPLANT to make accurate 3D models of the vessel components, from the hull to the superstructure. Designing the engine rooms was simplified by the ability to copy parts from one vessel to the next, and AutoPLANT Piping expedited the ISO extraction process, which required about 800 ISOs per vessel type.
“Without the auto-ISO routines of AutoPLANT, we would still be struggling to deliver the 1,600 ISO drawings,” said Steinar Ingvaldsen, senior pipe designer at LMG Marin. “The time saved by using AutoPLANT can be roughly calculated to be 3,200 hours, compared to making manual drawings. With the added benefit of copying parts from one vessel to another, I estimate that we saved in total about 5,000 hours.”
Based on an engineering man-hour cost valued at $100 an hour, Ingvaldsen estimated that the Bentley solutions produced a return on investment of roughly eight times the cost of software licensing, training, and customization. The 3D design models also helped the owner-operator visualize and approve the equipment layout and pipe design, speeding delivery of detail construction drawings to the shipyards. Ship hulls and superstructures were constructed in Romania, where severe weather caused some delays. When the hulls arrived at the shipyards in Norway, they were quickly outfitted with the prefabricated parts.
By early January 2007, all five vessels were in service, shuttling passengers and vehicles along the second and third most frequently used ferry routes in Norway — burning clean natural gas to reduce pollution.
