A Study On Optimize Design Of The Fin Stabilizer For SWATH Ship

SWATH ship has better seakeeping performance, less resistance at middle and high speed, and larger deck area than any traditional ships. It can meet with various kinds of conditions, and be paid more and more attentions by many countries. But the trimming counter moment of SWATH is always reduced, especially in high speed, because of small waterplane area. Furthermore, as the speed increases, the destabilizing 'Munk' moment increases rapidly as the square of speed, hence, that makes the ship easily to lose its stability, even lose its navigating ability. To overcome this problem, fin stabilizer is the most effective equipment.After introducing the structure characteristic and performance of SWATH ship, the developing course in the worldwide area during the past 50 years is reviewed. Then, the coupled heave and pitch equations of SWATH is established, where hydrodynamic coefficients associated with the motion equations are obtained according as strip theory method that developed by Lee.C.M. And the Routh stability criterion e > 0 is used to study SWATH stability. From which, there are three performance parameters: the nature period, damping ratio and half-decay time be derived. After that, factors such as the size and the location of the fin stabilizers and their combination are studied to grasp rules of these factors influencing motion performance and stabilizing characteristics of the SWATH ship. Finally, basing on the method, a full size SWATH ship is studied, and its fin stabilizer is designed in the paper.