JANUARY 28, 2013 — General Dynamics NASSCO reports that it has finalized a contract with Totem Ocean Trailer Express (TOTE) to design the conversion of the company's two existing Orca Class, diesel-electric trailerships to liquefied natural gas (LNG) propulsion.
In August last year TOTE received a permit providing a conditional waiver from the current Emissions Control Area (ECA) fuel sulfur content while it pursued conversion of the vessels to LNG (see earlier story).
The design contract reported today is in addition to the new-construction order that TOTE Shipholdings placed with NASSCO last month for the construction of two new LNG-powered containerships (see earlier story).
"We are very excited to be engaged in another LNG project with TOTE," said Fred Harris , president of NASSCO. "This project provides yet another sign that we are in the dawn of a new era of LNG propulsion. NASSCO will be a leader in the design, construction and conversion of ships to take advantage of the economic and environmental benefits of LNG."
The shipbuilder says that the TOTE conversion and new-construction projects validate its reputation as one of the nation's leading shipyards for commercial and government new construction. It says that the projects add to the engineering and construction capabilities the shipbuilder offers customers and leverages its design/procurement partnership with Daewoo Ship Engineering Company (DSEC), as well as its recent investments in people, facilities and equipment.
Conversion of the ships to LNG propulsion will significantly reduce or nearly eliminate the sulfur oxides, nitrogen oxides, carbon dioxide (SOx, NOx, and CO2) and particulate matter from ship emissions when compared to traditional diesel fuel. In recent years, there have been large increases in the cost of diesel fuel as well as stricter emission regulations. These factors, along with the environmental benefits made possible by the new technology, make LNG propulsion attractive for many new shipbuilding and conversion projects.
The 839 ft Orca Class ships - Midnight Sun and North Star - which operate between Tacoma, Wash., and Anchorage, Alaska, were designed and built by NASSCO. Both ships were delivered in 2003.
They are twin-screw diesel-electric with total installed power of 52.2 MW. The main engines are: 4 (each) MAN B&W 9L 58/64 and 2 (each) MAN B&W 9L 27/38 medium speed diesels at 400 and 720 rpm respectively
The diesel engines are designed to operate on both Heavy Fuel Oil, ISO 8217 Grade RMH 55 or Marine Diesel Oil, ISO 8217 Grade DMC
The electric propulsion plant is an Alstom 6.6 kV system; each motor is synchronous, variable speed, reversible, brushless, double-wound and rated at 19.75 mW at 125 rpm
Synchroconverters facilitate starting and speed control of main propulsion motors