Hannay was an original member of the Navy Records Society on its formation in 1893, and two years later he edited one of the society's first volumes, "The Letters of Lord Hood." Perhaps the best known of his books was "A Short History of the Royal Navy," in two volumes, which appeared in 1898 and 1909. It is especially valuable for students and was largely the outcome of Hannay's work as a lecturer at the Royal Naval College, Greenwich. A later work (1912) was "The Sea Trader: His Friends and Enemies," written as a companion volume to Commander Robinson's "The British Tar in Fact and Fiction." In 1914 Hannay produced for the Cambridge University Press a volume on "Naval Courts-Martial," a representation of the old Navy down to the Napoleonic Wars as it is pictured in the Court-martial records. In 1926, he wrote "The Great Chartered Companies," a survey of their history from the Genoese establishment at Chios in the fourteenth century.