Abstract

During the last twenty years, Damen Shipyards, a multinational shipbuilding group with 6000 employees worldwide, has done extensive research on the development of hull designs for fast monohull vessels. In the 1990s the Enlarged Ship Concept was developed, leading to highly improved sea keeping capabilities and vessel behaviour in waves at high speed. This hull design concept was applied in the Damen SPa 4207 patrol vessel and has proven extremely successful, reducing vertical accelerations by 50% and, thus, allowing vessels to keep operating at high speed in waves. Over 25 units of the Damen SPa 4207 have been delivered so far. After the successful introduction of the Enlarged Ship Concept, Damen and Delft University continued developing the next generation hull form: the axebow design. Compared to the already good sea keeping capacities of the Enlarged Ship Concept, model tests indicated a further reduction of vertical accelerations. This was proven by real-time measurements on the first built axebow vessels in 2006 and 2007. In the last 3 years, over 30 axe bow supply vessels have been delivered to very satisfied operators. As a next step, Damen has applied the axe bow design to the latest patrol vessel design, the Damen SPa 5009. The first vessel of this design is currently under construction and its trials are scheduled by the end of 2011. The paper describes the background of the research done by Damen and Delft University, focusing on the mathematical and scientific aspects of the axebow design and its application on various ship types. The development and design of the latest Damen patrol vessel, SPa 5009, will be introduced, describing its seakeeping performance, operatability and crew ergonomics. Finally, the paper will mention the current and future research topics that Damen and Delft University are working on together, identifying the developments of the future generation patrol vessels.

Highlights

  • The combination of high forward speeds and waves of any significance has since considerable time been a serious challenge for designers and operators of fast ships

  • The possibility of a fast ship to maintain its intended high forward speed under those conditions is a serious measure for its operability

  • From full-scale experience, it is known for a long time that severe motions and, in particular, high vertical accelerations are the main reason for speed reduction of fast ships in a seaway

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Summary

Introduction

The combination of high forward speeds and waves of any significance has since considerable time been a serious challenge for designers and operators of fast ships. The emphasis in the design of fast ships has been put on the minimal obtainable resistance at the required maximum speed This had to be obtained under calm conditions. The focus on calm water performance has lead to particular trends in the fast ship designs, such as low deadrise, low length to beam ratios, and relatively short and heavy hulls, i.e., low length – displacement ratios. These trends, showed unfavourable for the behaviour of these fast ships in a seaway. Thereby, when these ships moved their operational areas from the more sheltered inland waters to the more exposed sea areas a new design philosophy had to be developed

Problem Definition
The development of new design concepts
Negative vertical acceleration
Development of new active controls
Nozzles only crests troughs
Findings
Conclusions
Full Text
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