# Numerical Simulation of Seakeeping Performance on the Preliminary Design of a Semi-Planing Craft
## 5 Conclusions  
This study established a seakeeping program combining two-dimensional strip theory with the two-dimensional Green function based on the potential theory to solve boundary values and motion responses of a semi-planing craft. The simulation results can be used to help examine the seakeeping performance of high-speed crafts and to create a database for further route planning. By comparing the calculation results with those measured from on-board measurements, the reliability of the calculation results was confirmed. The findings are as follows:  
1. The swaying motion was strongly affected by beam waves at low sailing speeds and by quartering waves and increases in trim angle at medium and high speeds. The swaying motion was strongly affected by increases in sailing speed and worsening of the sea state.
2. The heaving motion was strongly affected by beam waves at low sailing speeds and by bow and head waves at medium and high speeds. The heaving motion was not affected by the trim angle for any sea state but was strongly affected by increases in sailing speed and worsening of the sea state.
3. In beam waves, the rolling motion decreased as the sailing speed and trim angle increased. The rolling motion was strongly affected by worsening of the sea state, particularly in beam waves.
4. The pitching motion was evidently influenced by head seas at low or high sailing speeds, and by worsening of the sea state at medium sailing speed or in following seas. The pitching motion was relatively unaffected by trim angles for all sea states.
5. In beam waves the yawing motion decreased as the sailing speed increased, and increased when the trim increased. When the wave heading angle ranged from quartering to beam waves, the yawing motion was considerably dominated by worsening of the sea state.  
The simulation results were within an acceptable range, verifying the reliability of the methods introduced in this study for assessing the seakeeping performance of high-speed semi-planing craft in comparison with full-scale on-board measurements. Although the crafts usually have different trim angles at high speeds due to dynamic lift under various loading and draft conditions, this study only investigated the trim angles of 0\({}^{\circ}\) (even keel), 1\({}^{\circ}\) by the stern, and 2\({}^{\circ}\) by the stern. No predictions could be made for the trim angles at any sailing speed during the transition or planing modes. Thus, when analyzing the seakeeping performance of high-speed crafts in the future, the trim angles under various sailing speeds, loading and draft conditions should be considered to enable the prediction of seakeeping performance and improve the accuracy of simulations. Such information can provide designers with preliminary seakeeping performance information for high-speed crafts.  
[PERSON] is the principal researcher of this study, and [PERSON] conducts the numerical simulation and data analysis.  
This research was funded by Ministry of Science and Technology (Taiwan), grant number MOST 107-2218-E-006-052 and MOST 107-2221-E-006-229.  
The authors would like to express their thanks to the Ministry of Science and Technology for a grant under Contract No. MOST 107-2218-E-006-052. The authors also thank [PERSON] for his advice on this study.  
The authors declare no conflict of interest.