You NEED this book if you have a boat, if you are planning to work at sea, if you are going to do the Yachtmaster exam (theroy and practical), if you are a crew member, if you are going to do an OOW (officer of the watch) oral exam or simply just because you living by the Sea !! Good book to review all the coastal navigation. Always buy together with the Navigation Exercises book to test your skills. One of the MUST have book.