The hull plate of a trimaran cross-deck bottom is often subjected to slamming loads under high-level sea conditions, potentially causing severe structural damage. The objective of this study is to analyze the influence of the air cushion effect on the impact load of a trimaran cross-deck plate and propose a new type of hull plate for the cross-deck bottom in order to reduce the slamming load.

The two-phase flow problem of a trimaran ship section is simulated using the computational fluid dynamics (CFD) method. First, the accuracy of the numerical model is verified by comparing the predicted results with the experimental measurements. The influence of the air cushion on the slamming load of the trimaran cross-deck structure is then obtained by analyzing the evolution of the flow field. Finally, the influence of the air cushion is analyzed and the effects of different shapes and sizes of the proposed hull plate are evaluated.

The numerical results show two slamming peaks that appear during the process of a trimaran entering the water. The rectangular shaped plate reduces the slamming load by around 20% compared with the flat plate bottom.

The air cushion has a significant effect on the slamming load. A rectangular shaped hull plate can be used to cover the trimaran cross-deck bottom.