On O'Brien, I found that I could just relax into the nautical terminology and allow myself to not understand every word: just enjoy the texture. And after a couple of books you'll find you've picked most of it up. After a dozen books you can recognize the names of 20 different sails, and explain when they are used. I realize that doesn't sound like obvious fun, but it's embedded in great stories of adventure and friendship. I've read the whole sequence twice and it's one of the most enjoyable reads of my life.