Master and Commander by Patrick O'Brian

As the Royal Navy takes part in the wars against Napoleonic France, young Jack Aubrey receives his first command, the small, old, and slow HMS Sophie . Accompanied by his eccentric new friend, the physician and naturalist Stephen Maturin, Aubrey does battle with the naval hierarchy, with his own tendency to make social blunders, and with the challenges of forging an effective crew -- before ultimately taking on enemy ships in a vivid, intricately detailed series of sea battles.