# High-Expansion Foam: A Risk Control Option to Increase Passenger Ship Safety during Flooding
## 5 Conclusions  
The present work provides an overview of the possible advantages in terms of safety given by the installation of active and passive risk control options against flooding. Two solutions based on the application of high expansion foam were described, being part of the AREST system, a technology developed at the University of Strathclyde in collaboration with worldwide industrial partners. The focus on both passive (AREST P1) and active (AREST A2) countermeasures also concerns the mechanical properties of the foam, necessary to grant adequate permeability, adhesion, and cohesion characteristics to be efficiently employed onboard ships. The application on a reference cruise ship highlights the potential benefits in terms of increased stability margins provided by the system. These advantages can be evaluated by means of conventional static calculations, easily implementable by naval architects, providing results of clear interpretation by designers and cruise ship operators. However, it was demonstrated that, by adopting more advanced and higher fidelity time domain simulations in waves, more insight in the flooding process can be achieved, detecting design weaknesses in the ship's internal layout invisible to conventional calculations. The proposed approach to investigate the application of the AREST risk control option onboard passenger ships need to be further refined, studying a better synergy between static and dynamic analyses, which, in the present work, remains fully dissociated. The development of an integrated static-dynamic process will increase the advantages of using a dynamic damaged ship simulation in the ship design. Furthermore, the applications of deployable barriers, as in the case of the AREST A2 system, require a proper study of ship evacuation, in such a way to prevent the interruption of principal escape routes crucial for ship evacuation. Nonetheless, the present work clearly indicates that the application of modern technologies employing foam materials, as the AREST system, is the right way to further increase ship safety against flooding, without employing drastic changes in the internal layout of the vessel, thus decreasing the earning capacity of the ship. \begin{table}
\begin{tabular}{l c c c c c c c} \hline  & & \multicolumn{2}{c}{**Existing**} & \multicolumn{2}{c}{**AREST P1**} & \multicolumn{2}{c}{**AREST P1+A2**} \\ \hline
**ID** & **GM (m)** & **GM Rag. (m)** & **GM Margin (m)** & **GM Rag. (m)** & **GM Margin (m)** & **GM Rag. (m)** & **GM Margin (m)** \\ \hline LC1 & 2.83 & 2.65 & 0.18 & 2.49 & 0.34 (+5.65\% GM) & 2.40 & 0.43 (+8.83\% GM) \\ LC2 & 2.64 & 2.50 & 0.14 & 2.29 & 0.35 (+7.95\% GM) & 2.21 & 0.43 (+10.98\% GM) \\ LC3 & 2.56 & 2.51 & 0.05 & 2.31 & 0.25 (+7.81\% GM) & 2.23 & 0.33 (+10.94\% GM) \\ LC4 & 2.56 & 2.53 & 0.03 & 2.34 & 0.23 (+7.81\% GM) & 2.24 & 0.32 (+11.33\% GM) \\ LC5 & 2.55 & 2.54 & 0.01 & 2.35 & 0.20 (+7.45\% GM) & 2.26 & 0.30 (+11.37\% GM) \\ LC6 & 2.94 & 2.62 & 0.32 & 2.46 & 0.48 (+5.44\% GM) & 2.38 & 0.57 (+8.51\% GM) \\ LC7 & 2.66 & 2.55 & 0.11 & 2.36 & 0.30 (+7.15\% GM) & 2.27 & 0.39 (+10.53\% GM) \\ LC8 & 2.68 & 2.51 & 0.17 & 2.30 & 0.38 (+7.84\% GM) & 2.22 & 0.46 (+10.82\% GM) \\ \hline \end{tabular}
\end{table} 
Table 10: Loading conditions and GM margins for cruise ship C1 with AREST systems. **Author Contributions:** Conceptualization, D.V., F.M. and D.P. ; methodology, D.V., F.M. and D.P. ; formal analysis, D.P., G.A., P.A., A.J. and F.M. ; investigation, D.P., G.A., P.A., A.J. and F.M. ; data curation, D.P. and F.M. ; writing--original draft preparation, F.M., D.V. and D.P. ; writing--review and editing, D.V., D.P. and F.M. ; visualization, D.P. and F.M. ; supervision, D.V. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by the Scottish Government, grant number SA1256, Royal Caribbean Cruises, MINOVA, and Maritime Safety Innovations, Ltd. (Glasgow, UK). **Informed Consent Statement:** Not applicable. **Data Availability Statement:** Not applicable.