The necessary techniques for safe navigation are described in the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (hereinafter, STCW) of the International Maritime Organization (IMO). The techniques included in the STCW range from those necessary for safe navigation to those necessary when working in teams. This book focuses on ship handling techniques by plural seafarers and the necessity of bridge team management (BTM). BTM is intended to ensure safety. Therefore, first, the conditions necessary for realizing safe navigation are discussed.