The influence of ice classification on design of an offshore supply vessel

Abstract

It is estimated that 22% of the worlds remaining petroleum resources are located in the Arctic region and 88% are located offshore. To produce these resources is it needed with equipment that can handle the environmental conditions in the Arctic, since it can be really harsh and very vulnerable at the same time. With increasing activity in this area new concepts and designs of vessels are needed. This and the fact that there are developed new rule requirements for ships for operation in ice-infested waters, increase the necessity of comparison of different ice classes and the identification of the most optimum structural arrangement regarding weight for the different ice classes for ships that are going to operate in the Arctic. In this thesis has it been developed a tool that utilizes a Particle Swarm Optimization algorithm in the search after the optimum structural arrangement for different ice classes. The tool compares ice classes for the two different rule sets DNV Vessels for Arctic and Icebreaking Service and IACS unified requirement (URI1-URI3) Polar Class and in the same time identifies the most optimum structural arrangement for each class. The tool has been used to do a comparison on both a platform supply vessel and an oil tanker to be able to see if there are any differences in ice classification between different types of vessels and in the choice of ice class and to show that the tool can be used for any type of vessel. The results for each comparison have been presented and compared, and the results show that the sensitivity in the choice of structural arrangement for an ice class and what ice class that is the lightest will differ from the type of the vessel and to what ice class that is chosen.It is in example shown that for the oil tanker that ice class PC-5 will be heavier than ICE-10, but for the platform supply vessel is it shown that ICE-10 are heavier than PC-5. This means that the necessity of a tool that can do a quick and accurate comparison of ice classes like the tool developed in this thesis are important. Especially in the early phase in development of a new design that needs a quick and accurate estimation of the hull structural weight and an indication of what the most optimum structural arrangement would be.