NEWS

Hamburg-based Ship Manager plays major LNG role

Hamburg is normally thought of as a maritime centre with container-ship, ship management and finance expertise, but one of the city's leading ship operators PRONAV Ship Management GmbH & Co., KG (PRONAV) have broken the mould by taking a major role in the burgeoning market for large LNG carriers of over 200,000 cubic metres in capacity.


PRONAV chosen by QartarGas

PRONAV is one of two ship operators to be chosen by the QatarGas consortium for the first train of large LNG carriers to be built in Korean yards. PRONAV currently has four 210,100 cubic metre GTT No 96 membrane-type LNG carriers on order to Lloyd's Register class from Daewoo Shipbuilding and Marine Engineering & Co., Ltd, to be delivered in 2007 und 2008. The ships will carry mainly gas from Qatar to the UK and occasionally to the US, and the full train of eight ships is expected to transport 8 million tons of LNG per year for the next 25 years.


New innovative LNG carriers

The QatarGas ships represent a major step forward in terms of LNG carrier size, an innovation driven by the increasing demand for LNG and the need to reduce long-haul transport costs from the Middle East to the US. Several technical factors have been considered in the design of these ships, including tank size and configuration and propulsion.

There are two options for a larger ship - five tanks of conventional size, or four larger tanks. The five-tank configuration is inherently less 'risky' as knowledge of the ability of a containment membrane to withstand sloshing loads is based on tanks of conventional size. Further, model testing demonstrates that the highest fluid pressures are associated with diagonal tank motion - lengthening the tank and hence the diagonal could result in more pressure on the tank membrane. The PRONAV ships will have 5 tanks each.

New propulsion options have also come to the fore for large LNG carriers, with traditional steam turbine propulsion becoming less attractive due to the sheer size of the proposed vessels. The sheer size of the vessels has led to the development of twin-skeg, twin-screw arrangements as a means of maintaining normal trading speeds. Further, the draught limitation imposed on the new generation of LNG tankers makes it difficult to design an efficient propeller or hull form for a single-screw vessel. The industry has therefore turned towards a number of new propulsion options: These are:

         • dual-fuel diesel electric
         • gas turbine
         • twin slow-speed diesel with reliquefaction.

QatarGas and PRONAV have opted for the latter, making these ships the first of their type to utilise slow-speed diesel propulsion with reliquefaction.

"These ships are highly innovative, taking a number of major steps forward in several key areas of LNG ship technology, all at the same time," says Gerhard Thies, Head of Marine Services in Lloyd's Register EMEA's Hamburg Office. "As the leading classification society for LNG ships. Lloyd's Register is committed to providing PRONAV with the correct level of support it requires during construction and during service life."