Structural Design Considerations Of High Speed Vessels

In conventional ships, which operate in any geometrical seas with appropriate speed, however, high speed vessels shall operate in particular sea state with its allowable service speed. In addition, because of lightweight construction and higher service speed, the dynamic effects is more pronounced in high speed vessels and that lead to higher dynamic loading which is significant in high speed vessels structural design. Therefore, structural design considerations are different between high speed vessels and conventional ships.This thesis presents the structural design considerations for high speed vessels. Due to the natures of the high speed vessels such as specific sea state operation and significant effects of dynamic loading, structural desiga considerations emphasized the environmental and limit operating conditions and design loads applications, which are important role in high speed vessel's structural scantlings determination.In structural design calculation procedure, global and local design loads are calculated according to service restrictions and limit operating conditions, and overall or hull girder and local strengths are evaluated from global and local design loads. Then scantlings are determined accordance with strength criteria. In this thesis, three Classification Societies (i.e. ABS, BV, and DNV) rules are applied for discussion of this procedure. Furthermore, because of the lightweight requirements, construction material consideration is required in high speed vessel's structural design and this is also discussed.Direct calculation is also presented in scantling determination, which required in larger or more complex vessels, to confirm the adequacy of the formula based scantlings, and to give reduced scantlings, especially when optimization routines are incorporated.In high speed vessel's structural design, fatigue is more important than conventional ships. Furthermore, if direct calculation is used for structure optimization, fatigue analysis will be required for fatigue criteria consideration. Therefore, fatigue strength assessment are discussed with two fatigue analysis approaches (i.e. fracture mechanics approach and SN - Miner-Palmgren approach).In addition to these, concepts of fabrication and quality assure are also discussed in this thesis, which are required in structural design considerations to improve and achieve adequate quality of structural design.