Abstract:In order to improve the seakeeping performance of traditional planing craft in waves, this article proposes a variable structure planing craft with both speedability and seakeeping performance, which realizes the free conversion between mono-hull state and trimaran state by rewind and release of two demihulls. In order to analyze the anti-roll effect of the demihull in inclined waves sailing, the numerical method is used to compare the seakeeping performance of the two states of planing craft in the inclined wave sailing. The results show that the demihull can reduce roll, and the anti-roll effect is most obvious in the resonance region of the mono-hull. When the βw=60°, the body can reduce roll amplitude by 70.45% at most.