Sloop of War by Alexander Kent

The Year is 1778, the ship is the 18-gun HMS Sparrow, England's finest sloop of war, and the captain is Richard Bolitho, sailing his command into the fury of battle. The American Revolution has turned the Atlantic Coast into a refuge for privateers and marauding French warships. It is up to young Bolitho to fight the colonial rebels, to stave off the treachery of a beautiful woman, and to overcome the dangerous incompetence of a senior officer before it is too late.