The Steam warship classification system used during the 19th century was a classification scheme for the comparison of steam warships, including steam frigates and steam sloops. The system originally classified steam warships according to the thrown weight of their broadsides, then rated them by tonnage, using separate standards for ironclad and non-ironclad ships, with allowances for sailing ships still in commission. It was used in the United States and United Kingdom, officially and unofficially. The United States Navy adopted the system by 1875.
Ratings First system (Civil War-at least 1870) Source:
(Weights given are representative)
TypeShot weight (lbs)First Rate2,606 Second Rate1,220 Third Rate434 Fourth Rate210 / 294
Second system (by 1875) Source: TypeTonnage (non-ironclad)Tonnage (ironclad)First Rate (also sailing ships-of-the-line) 4000 + 8000 + Second Rate (also sailing frigates) 2000 - 4000 2000 - 8000 Third Rate (also sailing sloops of war) 900 - 2000 1200 - 2000 Fourth Rate (also dispatch vessels and store ships) 0 - 800 0 - 800
References