Book excerpt: Terrestrial Navigation: A Primer for Deck Officers and Officer of the Watch Exams prepares the reader for the Officer of the Watch and Master/Mate certificates required by all officers on commercial seagoing vessels. Revision and self-test guide to all navigation-related elements contained within the Officer of the Watch exams are included. Top tips are highlighted throughout the book. The case studies and checklists have been designed to add context and aid recall. From basic trigonometry and plane sailings plotting, right through to practice questions with answers, and mock exam papers, this book will provide you with all the reference material you need to pass your exams.