Probabilistic Concept of Ship Subdivision Applied to Tankers Oil Outflow Assessment

Ferreira, Sergio Paulo Alves (1999) Probabilistic Concept of Ship Subdivision Applied to Tankers Oil Outflow Assessment. MSc(R) thesis, University of Glasgow.

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The oil tanker designs have suffered significant changes during the last few years. These forced modifications were a result of the introduction of recent international (IMO, 1995) and domestic (OPA '90) regulatory actions. Intensification in the research work was also noted during this last decade, giving special attention to the prediction of tanker environmental performance in collisions and groundings. Agreeing that the probabilistic concept is the only rational tool that enables a true comparison of different tanker designs, the mathematical basis for the probabilistic concept is described with references to the most important authors and their contribution to the development of probabilistic based regulations. A review on the development of international regulations for control of oil pollution from tankers is presented, with statistics of the most important accidents, in terms of oil spills. A mathematical model was developed, integrating the latest IMO regulations, using a direct probabilistic methodology. This methodology incorporates distributions of damage location and damage penetration as derived by several Classification Societies and compiled by IMO. The method was enhanced with the characteristic of not assuming total width extent of damage in case of groundings, enabling this way the assessment of the influence of longitudinal subdivision in the cargo space and in the double-bottom. Expected oil outflow calculations were performed for 107 different tankers, including Pre-MARPOL, MARPOL, Double-Hull and Mid-Deck designs. Initial oil losses following impact and oil retention in the double-hull space were taken into consideration, as well as tidal drop and dynamic effects. The work carried out include: parametric studies, varying double sides width, double-bottom heights, number and location of longitudinal bulkheads, number and location of transversal bulkheads and location of horizontal bulkheads; double-hulls comparison; different design types comparison and environmental performance ranking. A discussion of the resulting probabilistic oil outflows is presented with comparisons of the environmental characteristics of the sample tankers. These sample tankers include both variations of internal subdivision within the same ship type and also among different design types. From the analysis it was found that, in general, the mid-deck tanker designs have lower oil outflow rates, when compared with the other designs, including double-hulls. It was also concluded that the subdivision of the cargo block region has a determinant influence on the calculated expected oil outflows. A short description of new design concepts is made, presenting the different characteristics of each and the advantages claimed by each author.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Additional Information: Adviser: Ian Winkle
Keywords: Naval engineering
Date of Award: 1999
Depositing User: Enlighten Team
Unique ID: glathesis:1999-75716
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 18:32
Last Modified: 19 Nov 2019 18:32

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