From January 1862 to March 1863, Fisher returned to the payroll at the navy's principal gunnery school aboard , a three-decker moored in Portsmouth harbour. During this time, "Excellent" was evaluating the performance of the "revolutionary" Armstrong breech-loading guns against the conventional Whitworth muzzle-loading type. During free afternoons Fisher would walk the downs, shouting to practice his command voice. He spent 15 of the next 25 years in four tours of duty at Portsmouth concerned with development of gunnery and torpedoes.