High-expansion foam: a risk control option to increase passenger ship safety during flooding

In naval architecture, the standard way adopted to reduce the risk of potential loss of life for passenger ships after an accident is via regulations. In case of flooding, this explicitly implies the introduction of fixed watertight bulkheads, permanently modifying the internal ship's layout. Damage stability regulations constantly aim at higher safety standards; therefore, the layout reconfiguration of an existing vessel may be essential to meet new requirements, leading to higher costs for retrofitting. Furthermore, increasing fragmentation of the internal layout has a physical limit, neglecting the possibility to elevate standards above a particular upper limit. In this view, innovative solutions give the chance to exceed such a limit. The present work describes the advantages of high-expansion foam application for passive and active protection from flooding events. The possibility to have a material granting sufficient water tightness allows installing fixed or deployable barriers that increase the safety level of the ship. Here, besides the description of the foam characteristics, the application on a reference passenger ship highlights the advantages of passive and active foam barriers to limit flooding and drastically reduce the risk of loss of lives. The changes in the limiting stability margins required by regulations and the analysis of dynamic flooding simulations for specific damage cases demonstrate the benefits of foam installation onboard passenger ships as a risk control option.