Ship and Offshore Structure Design in Climate Change Perspective

This book summarizes results of longstanding research and scientific contributions from many projects and relevant working groups. It collects and evaluates wind and wave climate projections under changing climate having design needs and marine safety in focus. Potential impact of projected climate change in met-ocean conditions on ships and offshore structures is discussed and illustrated by an example of the expected wave climate change on tanker design

SAFEDOR – the implementation of risk-based ship design and approval

The integrated project SAFEDOR has been completed in spring 2009 and this paper summarizes the achievements. SAFEDOR has been focusing work on the development of a risk-based regulatory framework, a risk-based design framework, advanced probabilistic simulation tools and their integration as well as a series of application examples. The paper outlines the elements of the risk-based regulatory framework incl. approval process, risk evaluation criteria, requirements for documentation and key personnel as well as onboard documentation. Novel risk-based simulation tools and their integration into a design environment are discussed. The paper also highlights the innovative ship designs developed within SAFEDOR and points towards possible future applications. Eventually, future research on risk-based approaches is outlined

Optimal Evasive Maneuver for a Ship in an Environment of Fixed Installations and Other Ships

Collision avoidance for encounters between several ships and installations in the open sea, is treated as a problem of optimal control, using the theory of differential games. Each ship is, in this idealized model, assumed to have two controls corresponding to rudder angle and engine setting. The objective function, which the shipmasters try to minimize in an optimal evasive manoeuvre, is defined as the collision risk. Numerical solutions for the M-ships and I-installations optimal evasive manoeuvre problem, can be found by the ping-pong algorithm. Numerical examples are given for up to five ships and two installations

Risk acceptance criterion for tanker oil spill risk reduction measures

This paper is aimed at investigating whether there is ample support for the view that the acceptance criterion for evaluating measures for prevention of oil spills from tankers should be based on cost-effectiveness considerations. One such criterion can be reflected by the Cost of Averting a Tonne of oil Spilt (CATS) whereas its target value is updated by elaborating the inherent uncertainties of oil spill costs and establishing a value for the criterion’s assurance factor. To this end, a value of $80,000/t is proposed as a sensible CATS criterion and the proposed value for the assurance factor F = 1.5 is supported by the retrieved Protection and Indemnity (P&I) Clubs’ Annual Reports. It is envisaged that this criterion would allow the conversion of direct and indirect costs into a non-market value for the optimal allocation of resources between the various parties investing in shipping. A review of previous cost estimation models on oil spills is presented and a probability distribution (log-normal) is fitted on the available oil spill cost data, where it should be made abundantly clear that the mean value of the distribution is used for deriving the updated CATS criterion value. However, the difference between the initial and the updated CATS criterion in the percentiles of the distribution is small. It is found through the current analysis that results are partly lower than the predicted values from the published estimation models. The costs are also found to depend on the type of accident, which is in agreement with the results of previous studies. Other proposals on acceptance criteria are reviewed and it is asserted that the CATS criterion can be considered as the best candidate. Evidence is provided that the CATS approach is practical and meaningful by including examples of successful applications in actual risk assessments. Finally, it is suggested that the criterion may be refined subject to more readily available cost data and experience gained from future decisions

Societal risk and societal benefits

Decisions based on risk analysis require some form of risk acceptance criteria. Presently the International Maritime Organisation (IMO) has initiated an activity on developing a risk-based approach to safety and environmental protection regulations. Explicit risk estimates are new to the organisation. A limited number of FSA trial apllications have been presented so far. Whilst giving increased general knowledge of the risk level in the industry, the debate about risk acceptance has just started.

Cost-effectiveness criteria for marine oil spill preventive measures

Oil tanker accidents resulting in large quantities of oil spills and severe pollution have occurred in the past, leading to major public attention and an international focus on finding solutions for minimising the risks related to such events. This paper proposes a novel approach for evaluating measures for prevention and control of marine oil spills, based on considerations of oil spill risk and cost effectiveness. A cost model that incorporates all costs of a shipping accident has been established and oil tanker spill accidents have been further elaborated as a special case of such accidents. Utilising this model, novel implementation criteria, in terms of the Cost of Averting a Tonne of oil Spilt (CATS), for risk control options aiming at mitigating the environmental risk of accidental oil spills, are proposed. The paper presents a review of previous studies on the costs associated with oil spills from shipping, which is a function of many factors such as location of spill, spill amount, type of oil, etc. However, ships are designed for global trade, transporting different oil qualities. Therefore, globally applicable criteria must average over most of these factors, and the spill amount is the remaining factor that will be used to measure cost effectiveness against. A weighted, global average cleanup cost of USD 16,000/tonne of oil spilt has been calculated, considering the distribution of oil tanker traffic densities. Finally, the criteria are compared with some existing regulations for oil spill prevention, response and compensation (OPA 90)