Seventy - four ( ship ) The " seventy - four " was a type of two - decked sailing ship of the line nominally carrying 74 guns . Originally developed by the French Navy in the mid - 18th century , the design proved to be a good balance between firepower and sailing qualities , and was adopted by the British Royal Navy ( where the ships were classed as third rate s ) , as well as other navies . Seventy - fours were a mainstay of the world ' s fleets into the early decades of the 19th century , when they were supplanted by improved construction techniques allowing larger vessels and by the introduction of steam power . First 74 - gun designs . The classic 74 - gun ship was invented by the French as they rebuilt their navy during the early years of the reign of Louis XV . The new ship type was a very large two - decker big enough to carry the largest common type of gun ( 36 - pounders ) on the lower gun deck , something only three - decker s had done earlier . This great firepower was combined with very good sailing qualities compared to both the taller three - deckers and the shorter old - style 70 - gun two - deckers , making the 74 the perfect combination of the two . A disadvantage of the 74 was that it was relatively expensive to build and man compared to the older type of two - decker . The 74 - gun ship normally carried twenty - eight 32 - or 36 - pound guns on the lower gun deck , thirty 18 - pounders on the upper gun deck , and sixteen 9 - pounders on the upper works . A limited number of seventy - fours were built for 24 - pounders instead of 18 - pounders , but this was not common due to the increased cost and also tended to overload the hull . Crew size was around 500 to 750 men depending on circumstances and nationality , British ships tending to have smaller crews than comparable Continental ones . The French have large and small seventy - fours , called " grand modèle " and " petite modèle " , the waterline length of a " grand modèle " seventy - four could be up to 182 feet . This was copied by the Royal Navy in about two dozen such ships of their own , such as the HMS " Colossus " where they were known as Large , while the other seventy - fours built to be between 166 – 171 feet were known as Common . Given the construction techniques of the day , the seventy - four approached the limits of what was possible . Such long hulls made from wood had a tendency to flex and sag over time . Increased maintenance could counter this to some extent , but this was of course costly . This limited the success of the even bigger two - deck 80 - gun ships that were built in small numbers after the seventy - four had been introduced . Three - deckers did not have the same problem due to their additional deck giving more rigidity . The significance of the 74s however is hard to overstate , as a summary of the ships of the line for all nations that were in commission at any time during the Revolutionary / Napoleonic Wars period . 74s in the Royal Navy . The Royal Navy captured a number of the early French 74 - gun ships during the War of the Austrian Succession ( for example , " Invincible " , captured at the first battle of Cape Finisterre in 1747 ) and the Seven Years ' War and were greatly impressed by them compared to their own smallish 70 - gun ships . As a result they started building them in great numbers from about 1760 , as did most other European navies . Navies that were restricted by shallow waters , such as the Dutch and Scandinavian navies , at least early on tended to avoid the 74 - gun ship to a certain degree due to its size and draught , preferring smaller two - deckers instead . Even so , the seventy - four was a standard feature in all European navies around 1800 . Only a handful of 74 - gun ships were commissioned into the United States Navy ; the US Navy ' s early sea power concentrated on their powerfully - built frigate s . The type fell into disuse after the Napoleonic Wars , when improved building techniques made it possible to build even bigger two - deckers of 84 or even 90 guns without sacrificing hull rigidity . The last seventy - four , the French Trafalgar veteran " Duguay - Trouin " , was scuttled in 1949 . Her stern ornamentation is on display at the National Maritime Museum , Greenwich . In addition , dozens of ship model s exist , produced as part of constructing the real ships , and thus believed accurate both externally and internally .