Harpoon III Advanced Naval Warfare has to be the best overall computer naval sim that I've ever played and not only the manual, but the whole game itself is an EXCELLENT exercise in modern naval tactics. I can even say the same for the tabletop miniatures version of the game.
As a matter of fact, the manual for the miniatures tabletop version.. (Called Harpoon4 now) is such an educational read that I definitely reccomend it for learning about almost everything involved in modern naval warfare. It's funny because the manual is so long and intimidating looking. The game system is actually pretty simple, but they pack so much information about naval warfare into the manual that it appears more complicated than it is. I think it's actually a lot more informative than the videogame version's manual. I learned a lot more about modern naval warfare from reading that manual than almost everything else I've read on the subject. The game costs, but it's well worth it if you really want something educational to read and a good game as well. Harpoon4 is part of the Admiralty Series.. basically super accurate tabletop miniatures versions of naval warfare going from WWI to modern. All the manuals for the three games are fantastic educational studies in naval warfare of the periods covered.
http://www.clashofarms.com/miniatures.html
Even though these games rarely make it to my game table, I still found them to be excellent and educational reads.