The increase in world trade has largely contributed to the enormous growth in sea traffic. As a result, the market demand is leading to Ultra Large Container Ships ('ULCS'). These have a capacity up to 14 000 TEU, lengths up to 400 meters and similar operational requirements (speed around 27 knots).
The structural design of such ULCS container ships, with open midship sections, will result in an increased sensitivity to torsional and horizontal bending loads. At the same time, due to larger dimensions, the structural natural frequencies of ULCS become significantly lower. Thus, hydro elastic structural responses (springing & whipping) can become a critical issue in ship design and should be properly modelled by simulation tools.
However, it appears that existing simulation tools do not provide the definite answer to all these design issues. There is a clear need for their improvement. The importance of whipping and the insufficient knowledge in its modelling, is clearly reflected in the recent MAIB (Marine Accident Investigation Branch) report, following the loss of the MSC Napoli container ship.
The goal of the TULCS project was to deliver clearly validated design tools and guidelines, capable of analysing all hydro-structure interaction problems relevant to ULCS.
It is likely that the hull of the MSC Napoli was subjected to additional loads due to whipping. Furthermore, it is apparent that the whipping effect is currently very difficult to calculate or model in a reliable way.
In view of the potential increase in wave loading due to whipping effect, further research is required to ensure that the effect is adequately accounted for in ship design and structural analyses, and that sufficient allowance is made for the effect when determining design margins. The final goal of the project is to deliver clearly validated design tools and guidelines, capable of analysing all hydro-structure interaction problems relevant to ULCS.
The main results can be summarised as follows:
- In particular all the model test campaigns were successfully performed and useful databases for validation of the numerical tools were produced. In that respect, it is important to mention that the test matrix for hydro-elastic model of the Rigoletto container vessel was significantly extended, thanks to cooperation with EU project EXTREMESEAS.
- The analysis of the model test results is finished. Comparisons with numerical tools are continuing. In addition to the complex model tests campaign on Rigoletto, which was performed by CEHIPAR, an additional model test campaign devoted to slamming impact problems, was also performed. This campaign showed to be very useful for validation of the slamming modules which are the critical part of the whole physical problem.
- On the numerical side, most of the developments with respect to hydrodynamic, structural and hydro-structural tools have been finalised successfully. Verifications have been performed and different numerical tools can be used independently as stand-alone codes.
An efficient and integrated mobility system:
- Secure Transport
- Acting on Transport safety (saving thousands of lives)