Here's some advice about that. I can't tell a spar from a jib boom and I get sea sick more than 10 feet out to sea from the surf line. I never tried to master a lot of the really nautical talk in the books, it was too distracting from the story line and the characters. The real meat and bones of those novels are Aubrey and especially the ship's surgeon and intelligence operative Maturin. The other characters sometimes pass into and then out the novels over the course of 2-5 of them, so the cast of characters while changing a little is much easier to keep track of than say all them damn rooskies in War and Peace.
If you like the genre, I also highly recommend Dewey Lambdin's books. Captain Lewrie is a regular Harry Flashman at sea and he portrays a much wider view of the ship's operations and crew than O'Brian does.