The Behaviour of Tugs in Waves Assisting LNG Carriers During Berthing Along Offshore LNG Terminals

AuthorsBas Buchner, Pieter Dierx and Olaf Waals
Conference/JournalOMAE Conference, Halkidiki
DateJan 1, 2005

For future offshore LNG terminals tugs are planned to assist LNG carriers during berthing and offloading operations. A model test study was carried out to better understand the tug behaviour in waves and to make a first step in the quantification of the related weather limits. Scale 1:35 model tests were performed in the two important 'modes' of a tug during this type of operation: the 'push' mode and the 'pull' mode. Realistic weather conditions were used and the tugs were working at the unshielded and shielded sides of the LNG carrier. Based on the results presented in this paper, it can be concluded that the motions of tugs in waves are significant, even in wave conditions that are considered to be mild for the berthing and offloading LNG carriers. The resulting push or pull loads may hamper these tug operations significantly. Special measures are necessary to take this behaviour into account in tug design, LNG carrier design and development of operational procedures and equipment. The paper gives insight in the typical tug behaviour in different weather conditions. One should be careful, however, to generalize the present results: with an optimised tug design and operation the tugs can be used in more severe conditions.

manoeuvring and nautical studiesstability, seakeeping and ocean engineeringwaves, impacts and hydrostructuralcfd developmentcfd/simulation/desk studiesmeasurements and controldata sciencesafe operations and human factorstime-domain simulationsmanoeuvringnautical operationsrenewablesoil and gasinfrastructuremarine systemslife at seadefencepassengers and yachtingtransport and shippingmodel testingloads and responsesmotionsoperabilitysimulationoffshore engineering