Since Electronic Chart Display and Information System (ECDIS) is a very important navigator for the safety of seafaring, a cadet of Seafaring Polytechnic should learn it at class. Cadet should master how to use it properly to improve effectiveness and efficiency in seafaring. But, ECDIS only in the ship and training fee is very expensive. Seafaring Polytechnic need simulator like ECDIS, but can easily use in the class. This study reports the development of simulator that applying spherical triangle concept to determine distance and direction of the ship. RnD has chosen in this research. To ensure accuracy, we will compare the result of measuring with simulator and ECDIS. 51 cadets of deck department were asked to respond trial sessions of simulator. This investigation points out that the performance of this simulator tends to ECDIS with 0.072% error in measuring distance and 0.16% error in determining the direction of the ship. For the trial sessions, 85% cadets give a positive response and 87% pass the passing grade. These findings suggest that this simulator can be integrated into the marine learning process in the class. For the next research can be developed a simulator that used the map with marine traffic.