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ABSTRACT

At shipyards, for ships' production, repairing and launching facility, the floating dock units are currently used. In any design and service stage, the following floating dock main capabilities have to be assessed: floatability, trim, stability and global loads. This paper presents the own developed FDOCK software package that integrates five modules: hydrostatics and draught survey (with dock deflection), sinkage and trim according to the lifting case, transversal stability with trim updated according to heeling angle, still water vertical bending moments and shear forces, having also the option to add small equivalent quasi-static wave loads that can occur in the shipyard basin or at relocation. The floating dock and water system balance in all the computational modules is obtained by iterative non-linear procedures, using a double definition of the off-set lines, external and internal between the two side wing tanks. As numerical study case is considered a floating dock with 60 m length, 20 m breadth, 2 m pontoon height, 8 m height, two constructive versions. Several operation scenarios are analyzed, testing all the software modules. Based on the numerical results, the operation capabilities of the floating dock unit are assessed.

Keywords: development of design software, floating dock unit, operation capabilities analysis.

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1.INTRODUCTION

One of the most versatile production unit in a shipyard is the floating dock unit, that requires reduced facilities on land and ensures also the docking and launching operations of the working ship [13], [31], [35].

The floating dock operating capabilities and safety must be assessed at any design and service stages for each working ship project by several criteria, according to the shipbuilding classification society's rules [1], [9], [10], [22]. For this purpose we have developed an own software package FDOCK, making possible to assess the following: the freeboard criterion corresponding to the floating and trim condition, the vertical global strength criteria by yielding stress and ultimate strength limits (global buckling), the general and weather transversal intact stability criteria.

As study case we consider a floating dock unit Dock60 with non-continuous (NWT) and continuous (CWT) side wing tanks [10], [31], overall length 60 m and maximum lifting capacity 828 t. The main operation scenarios are analyzed and the capabilities of the floating dock are obtained. The...

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