I found this book to be a wonderful aid to all seamanship skills. However certain sections are difficult to read and they require deep concentration(therfore the 4 star rating). This book is extremely useful in supporting work in college and at sea, throughout cadetship in the merchant navy.It not only aids the professional sailor, but has information for all private users as well.It is a comprehensive guide to all things nautical. A reference for a career minded individual, or a general aid to all pleasure sailors.