Master and Commander by Patrick O'Brien, 1970.
Both the accusations of "Tom Clancy on the high seas" and the hyperbole of "great literature" seem off the mark. The depth of characterization too well-done for the former, the tinge of "look how much research I've done!" too striking for the latter. I was also left with an impression of disjointedness overall.
Brian said this doesn't hold a candle to C.S. Forester, whom I don't recall ever reading. I found Commodore Hornblower in my collection, so I'll put that in the "read pretty soon" pile. I remember enjoying Mr. Midshipman Easy (Marryat), and the Swallows and Amazons series (Ransom) were favorites at one time, but I'm not that familair with sea stories as a genre.