Along with Paul Silverstone’s Warships of the Civil War Navies, this might be one of the most valuable source of technical specifications on the American Civil War naval era. Gun armaments, caliber, armor thickness, etc. are all specified. I would give it to Silverstone for focusing on the specific ACW era and providing more information on each hull, but also give credit to this book for the period directly after the war through the pre-dreadnought era, on which precious little has been written. Strongly recommend this one if you are interested in the technical side of the Civil War and afterwards.