The Global Maritime Distress and Safety System (GMDSS) - the maritime equivalent to the emergency services number - provides a fast and efficient way of calling for assistance at sea, whatever the size of craft or its location. Denise Brehaut explains the operation of the system as a whole and clearly outlines the procedures required to get help quickly, as well as covering the syllabi of the General Operator's Certificate (GOC), the Long Range Certificate (LRC) and the Restricted Operator's Certificate (ROC). Concise descriptions of channel usage, call signs, types of transmission and equipment allow novices as well as long-time users to thoroughly understand this life-saving communications system. The 6th edition of GMDSS incorporates all the changes to the regulations that came into force in 2009 as well as the 2016 system updates. GMDSS: A User's Handbook has proved an invaluable reference for exam candidates and equipment users alike for almost 20 years - it is the GMDSS bible. The clear and lucid text is supported with illustrations, handy Q&A sections and a quick-reference revision guide for GOC and LRC students. Since it was first published, this book has helped explain the system for anyone using GMDSS and has been excellent pre-course reading for students.