航程計畫的大洋航行，大圈航法之計算程序始終是首要工作，對資淺航海者而言，其在計算時，存在過多人工判斷以及因繁瑣的計算過程，使得計算程序不符實務要求；另外，多數現有的大圈航法之計算程式欠缺完整性及彈性，此引發了本文的研究動機。因此，本文提出一套整合大圈方程式法及直角球三的納皮爾法則等相關公式之計算程序，繼而採用 MATLAB®內建的圖形使用者介面，成功地開發出具有人性化且航海者導向的大圈航法之計算程式，並命名為CS_Departure；最後該自行開發之程式均透過實際的例題確認無誤。

The computation procedures of great circle sailings (GCS) are always the
primary task in open sea sailings of voyage plan. Many artificial judgments needed in calculation and the tedious process make these computation procedures impractical for inexperienced navigators. Besides, most relevant GCS computational programs are lack of completeness and flexibility. It leads to the motivation of this article. Therefore, an integral computation procedure combining the great circle equation method (GCEM) and Napier's rules of rightangled triangles is proposed and then, the Graphical User Interface (GUI) built in the MATLAB® is adopted to develop friendly navigator-oriented GCS program, namely the GCS_Departure. This self-developed program is verified with several examples presented in currently available books.