The one annoyance about this book (for people like me, who came to Patrick O'Brian's stories through my own devices, at least) is that, by the time you hear tell off this book, you are several volumes into Mr O'Brian's exquisite series... by which time, you've generally muddled through (with whatever miscellaneous assortment of secondhand reference works you have inherited from elderly relatives) and figured out, by yourself, what a "futtock shroud" might be, or (through sheer perseverance) discovered what a "Greek pollacca" looks like, and much of what this gem of a book could have given you in a flash is already lost!
If you ever find yourself in the privilaged position of being able to recommend Patrick O'Brian's magnificant novels to anyone who is so benighted as to have not yet heard of them, don't leave them in the lurch - funish them with a copy of this most excellent tome, to help them on their way! After all, you will remember the number of times you felt compelled to run to your meagre collection of reference sources to find out what O'Brian writes about with such unswerving authority. Even if you cannot gain from it youself, you know that this is _the_ book to have.
I cannot write too highly of it (and I am an able to write too highly of many things when the spirit takes me :). But, To give a copy of "Master and Commander" to a new initiate of Mr O'Brian without also furishing them with a copy of this book is, quite frankly, to condemn your fellow potential Aubreyites to the same fate as yourself - Heck, even I didn't know what a Dutch Galliot looked like until I bought this book!