Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
항해학항법은 배를 안전하게 운항하는 방법을 가르칩니다.hanghaehakhangbeobeun baereul anjeonhage unhanghaneun beobbeul galeuchimnida.Navigation teaches how to operate a ship safely.