Motion Response Calculation Of Trimaran In Wave

In recent years, the high speed trimaran, as a kind of high speed ship, caughtwide attention among the shipbuilding industry. Compared to a mono-hull ship, thetrimaran has many advantages, such as broader deck increasing bearing capacity,better seaworthiness, smaller running resistance, better stealth performance, lowerconstruction cost and much easier to be transformed. There has been extensiveresearch work on the resistance performance of high-speed trimaran, but the researchof seakeeping has just begun and needs further research and testing work. Theultimate purpose of research work is to optimize the ship type and improve theseaworthiness of trimaran.At present, we are familiar with the parameters which have main effects on theresistance performance of trimaran. They are the length of main body, the ship width,draft, prismatic coefficient, the longitudinal position of buoyancy center, speed, wavedirection and layout of side bodies, etc. To seek a ship form with better seakeeping,the high-speed trimaran designers should find out the factors influencing on themotion of trimaran at the beginning of design and use the favorable factors ofseakeeping during the design process. In previous research on seeking influencingfactors, the researchers generally did a large number of series model tests and madecomparison between the main influencing factors. Ossers with his team did modeltests on series60. D. Bailey et al. did series model test on NPL high speed round bilgetype model. Nowadays, model tests which cost a lot of manpower and materialresources, replaced by hull form optimization software gradually. Xiang Jiuyang[52]write a ship form transformation program, by which when change a parameter, byadjusting the another parameter, other parameters remain unchanged, one can realizethe systematic calculation for the series of ship form and get motion and load underdifferent parameters, which greatly simplifies the optimization process of the ship.Previous research of trimaran is in view of the three body ship with small sidebody. In this paper, a trimaran which’s side body has the same principal dimensionswith main body is on research. Side body can be adjusted horizontally or verticallyaccording to the need, so it’s called length adjustable high-speed trimaran. In thispaper, we use Wasim, a hydrodynamic analysis software, basing on three-dimensionaltime domain theory and the Rankine source method, to calculate the RAO of trimaranunder different speed, different wave direction and different layout of side body.According to the calculation results, the paper analyzes the seakeeping characteristicsof the high-speed trimaran and illustrates effect on ship wave resistance with different layout of side body, and thus find out the best layout of side body that under differentwave direction and speed.