Ice model tests in context of the investment value of an offshore vessel

Rüdiger Von Bock Und Polach*, Vinod Janardanan, Sören Ehlers

*Corresponding author for this work

    Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

    7 Citations (Scopus)

    Abstract

    Offshore activities and shipping in Arctic regions increased significantly in the past decade due to fossil resources. These areas hold about 15% of the worlds oil and gas. Exploration or transportation in such harsh Arctic environments possesses additional risks for the crew, the material and the environment. Hence, ships need to be able to handle low temperatures and ice impacts. Ice class certificates issued by classification societies reflect the ships level of ice capability. They are further required to be admitted to ice covered waters or particular regions in seasons with a certain probability of ice occurrence. In most cases, offshore operations are not continued in ice and ships need to transit through ice after abandoning a site upon ice arrival. However, the daily costs of such specialized vessels are high with up to 0.5M$ day that are not reimbursed in downtimes or transit. Therefore, in Northern Arctic regions a higher ice class can significantly enhance the ships workability and therewith its economic value. The lower Polar ice classes, respectively Baltic ice classes, can only be determined analytically with empirically validated formulae for common cargo ships. Other ship types and ships with low L/B ratios are typically required to prove their ice capability through ice model tests. Nevertheless, ice model tests determine only the ice class of the propulsion system, whereas the ice class of the hull structure is determined by calculations. Furthermore, ice model tests are typically conducted towards the end of the design phase where eventualmodifications are expensive and potentially threaten the construction schedule of the vessel. Often steel and equipment have already been procured and the manufacturing has begun. This paper presents an iterative procedure of ice model testing and design updates in order to enhance the performance of a particular offshore vessel to meet the requirements for a particular ice class. Thereby, it will be shown how an increase in investment costs for the design changes is compensated by the increasing value of the ships capabilities due to the higher ice class. Furthermore, the drop in value of the ship for the next lower ice class will be indicated as well as the economic consequences should the ship fail to reach the targeted ice class.

    Original languageEnglish
    Title of host publicationASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2012
    Pages545-554
    Number of pages10
    Volume6
    DOIs
    Publication statusPublished - 2012
    MoE publication typeA4 Article in a conference publication
    EventInternational Conference on Ocean, Offshore and Arctic Engineering - Rio de Janeiro, Brazil
    Duration: 1 Jul 20126 Jul 2012
    Conference number: 31

    Conference

    ConferenceInternational Conference on Ocean, Offshore and Arctic Engineering
    Abbreviated titleOMAE
    CountryBrazil
    CityRio de Janeiro
    Period01/07/201206/07/2012

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