Reddit mentions of Harbors and High Seas, 3rd Edition : An Atlas and Geographical Guide to the Complete Aubrey-Maturin Novels of Patrick O'Brian, Third Edition

You already have two of the books I own and BillWeld suggested the other! You could also pick up Musical Evenings with the Captain. It's a collection of cello and fiddle music which are all pieces that were mentioned in the series. I love listening to it while reading.

EDIT: I just realized, it's not the Illustrated Companion that I have. I've got Harbors and High Seas. They look a lot alike, so I'm not sure what the difference is. This book was great for checking maps while reading though.

If one starts reading those novels, I'd recommend getting some guides to aid in the lubber's understanding:

• A Sea of Words, lexical guide. Trust me, even if you're something of a sailor, you won't understand a good bit of what goes on in the books. Well, you'll probably get the general idea, but there's a lot of nautical nuance that will be utterly lost. Good even for seasoned fans of the series.
  
  
• Harbors and High Seas, geographical guide.
  
  C.S. Forester's Hornblower series is also great.
  
  I haven't tried the sci-fi RCN series, which was influenced by O'Brian, but I should give it a shot.

http://www.amazon.com/Sailing-Ships-War-1400-1860/dp/0831776560/ref=sr_1_1?ie=UTF8&qid=1405749703&sr=8-1&keywords=sailing+ships+of+war+1400-1860

http://www.amazon.com/Harbors-High-Seas-Edition-Aubrey-Maturin/dp/0805066144/ref=sr_1_2?ie=UTF8&qid=1405749730&sr=8-2&keywords=patrick+o%27brian+reference

http://www.amazon.com/Under-Black-Flag-Romance-Reality/dp/081297722X/ref=sr_1_1?ie=UTF8&qid=1405749757&sr=8-1&keywords=under+the+black+flag

all three good places to start. The second one is fantastic to have open and waiting while reading the O'Brian Books

Oh I envy you being able to read Patrick O'Brian for the first time. I firmly believe that the Aubrey/Maturin series is the greatest work of modern English literature.

I do know that the movie is actually based on the plot of The Far Side of the World, which is actually the tenth novel, and that the stole some of the best anecdotes from various novels. For example, the "lesser of two weevils" gag is from The Fortune of War, which is the sixth book.

Not sure what advice to give you before you embark on your journey but there's two major paths: using references to understand everything, and learning along with Maturin (PO'B uses Maturin to explain some of the more esoteric concepts and terms of square-rigged sailing). I wrote the following in a previous Reddit post:
>In Master and Commander, the first of Patrick O'Brian's brilliant Aubrey/Maturin series (which may very well be the best-written English-language books post-WWII), we are introduced to Stephen Maturin, the perpetual land-lubber who acts as a guide for the reader to the more obscure jargon used by sailors -- especially that of the Royal Navy during the heights of the Age of Sail.

>When Maturin is being given a tour of the HMS Sophie, his first ship deployment, he becomes perplexed by the language being tossed at him and asks, "You could not explain this maze of ropes and wood and canvas without using sea-terms, I suppose? No, it would not be possible. ... No; for it is by those names alone that they are known."

>And that is how it is with the language of sailing; like learning a foreign language, one must become familiar with its terms and jargon for there is no other language to define it.

As for references, there are two major ones: "A Sea of Words", which is a dictionary and general reference for sailing/nautical, naturalism, medicine, politics, and sometimes foreign-language dictionary, though sometimes it comes woefully short on obvious terms; and "Harbors and High Seas", an atlas which maps out the various locations and journeys of Aubrey's missions.

Enjoy! And feel free to ask me any questions regarding the series. I've got whole passages memorized lol

EDIT: I forgot to mention my favorite fact: Patrick O'Brian never stepped aboard a sailing vessel...