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The desired goal in developing this procedure is to identify appropriate arrangements and layouts for
passenger Ro-Ro vessels, by considering specific safety and techno-economic targets. The various
characteristicdparameters to be considered are grouped in the following two categories:
0 -, for example L/B, flare, height of the main vehicle deck, shear, camber,
presence of a ducktail, etc.
and -, i.e. possible layouts below (for example, pure transverse
subdivision, combination of transverse and longitudinal subdivision, presence of a lower hold) and
above the main vehicle deck (for example, presence of centre and/or side casings, transverse or
longitudinal bulkheads. combinations).
The mathematical model to be considered utilises application of first-principles approaches for the
determination of the probability of survival following large scale flooding, Vassalos & Konovessis
(2001), within a QRA-based design framework. A comprehensive QRA framework for passenger Ro-
Ro vessels has been developed during the Joint Northwest European Project, Spouge (1996). The
various elements and the logical sequence of the procedure are illustrated in Figure 2. The procedure
comprises of the following steps:
(1) Selection of risk acceptance criteria, as well as other design criteria, to be applied.
(2) Estimation of the frequency (probability) of an incident/accident occurring.
(3) Estimation of the cost of consequences.
(4) Estimation of the implied risk level and categorisation according to the severity of the
consequences.
(5) Consideration of safety-enhancing measures to improve undesirable risk leveis (these include
both available risk control options as well as parametric studies).
(6) Setting-up of the optimisation problem and consideration of an objective function appropriate
to perform trade-offs among the specified societal and techno-economic targets (criteria).
(7) All necessary iterations.

4 CONCLUSIONS

The elements of a procedure for the integration of a rational approach to damage survivability
assessment within the ship design process have been described. A major conclusion is that classical
optimisation techniques cannot be applied in isolation to derive effective solutions, but rather as a
means to fine-tune an already developed solution that nearly satisfies the criteria. These should
combine with environments that support decomposed objective functions where the behaviour of the
various attributes can be readily assessed and decisions on design variations pcrfonned, which when
integrated in appropriate design architectures can provide the necessary Design for Safety support,
Duffy (1 999).

References

Duffy A.H.B. (1 999). Future Developments in Design for Safety Support. WEGEMT Design for Sufi@
Confirence, 25-28 October 1999, University of Strathclyde, Glasgow, UK.
Saary T.L. (1 980). The Anulytic Hierarchy Process: Ptanning Priority Setting9 Resource Allocution,
McGraw Hill Inc. New York, USA
Spouge J. (1996). Safety Assessment of Passenger Ro-Ro Vessels. RINA International Seminar on The
Safify of Passenger Ro-Ro Vessels, Paper No. 7,7 June 1996, London, UK.
Vassalos D., Oestvik I. and Konovessis D. (2000). Design for Safety: Development and Application of a
Formalised Methodology. The Seventh International Murine Design Conference (IMK 2000). 2 1 -24
May 2000. Kyongju, Korea, 151-165.
Vassalos D. and Konovessis D. (2001). Damage Survivability of Floating Marine Structures - A
Probabilistic Approach. 7'he Twentieth International Conference on Ojjjhore Mechanics and Arctic
Engineering (OMAE 2001), 3-8 June 2001, Rio de Janeiro, Brazil.