ABSTRACT

Floating LNG Bunkering Terminal(FLBT) is a newly emerging offshore platform which can be regarded as a LNG station at sea. It has its own station-keeping system, while it is additionally moored with other vessels during LNG loading or unloading processes. The ship-to-ship mooring system is composed with a number of mooring ropes and fenders, which might trigger unexpected motions. In this study, eigenvalue analysis was conducted, which gives the resonant frequencies and modes of vessels induced by the ship-to-ship mooring system. These eigenvalues were drawn in the model test results. Finally, we figured out some notable characteristics induced by ship-to-ship mooring system.

INTRODUCTION

A demand on energy resources has been steadily increased according to the world population increasing. Among alternative resources which might supplement the present fossil fuels, a natural gas is considered as environmental-friendly as the emissions from this resource has almost no sulfur. Recently, a liquefied natural gas(LNG) has been studied as a marine fuel respond to the enhanced regulation on sulfur emission by International Maritime Organization(IMO).

In order to operate LNG fueled vessels frequently, the infrastructures shall be established properly. Since an onshore LNG supplying terminal has a potential danger of explosion, a new concept of offshore terminals have been considered. In Korea, a national R&D project has been conducted since 2014 in order to develop the core technologies of an floating type LNG bunkering terminal(FLBT). It aims to be moored at the certain target ocean sea, and receive LNG from LNG carrier(LNGC) and give LNG to LNG bunkering shuttles(LNG BSs) simultaneously.

FLBT is self-moored by the internal turret and catenary mooring lines, while LNGC and other LNG BSs are side-by-side(SBS) moored to FLBT with mooring ropes and fenders. As a number of ship-to-ship(STS) mooring lines or fenders are included in the LNG transfer process, it is necessary to figure out the effect of the STS mooring system precisely.

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