The original six frigates of the US Navy were ahead of their time in design. Though ships have changed dramatically, we still hearken to the days of USS CONSTITUTION and her five sister ships before we were a major naval power. It wasn’t possible for our fledgling nation to build a fleet which could surpass the Royal Navy’s ships of the line. So a design was required which could both outfight anything it couldn’t out sail, and out sail anything it couldn’t outfight. A Philadelphia ship designer by the name of Joshua Humphries was hired to design the new ships.
To achieve the required speed and gunnery advantage, several advances were required in the design of the Humphries’ frigates. First, was a problem of carrying a superior number of guns per displacement. When too many guns were loaded, ships’ keels could become overstressed causing a dangerous condition known as “hogging”, where the middle of the keel is slowly bent upward over time. In addition to negatively affecting the sailing characteristics of the ship, this condition could eventually make the ship unusable.
The solution to this problem was installation of pre-stressed diagonal riders rising from the keelson to major deck beams; effectively distributing the load across the entire keel. Further assisting with the distribution of the weight of guns was lock-scarphed planking, which “hooked together” thick planks, providing significant longitudinal strength. Another innovation involved the use of live oak, which was plentiful in the Americas, in the hull. Live Oak is much denser than the White Oak, which was widely used for hull construction at that time. To further enhance hull ruggedness, the gap between framing was reduced to only two inches, compared with two to four times that for other frigates of the day.
The capability of this new class of heavy frigates came as a surprise to the Royal Navy. After the battle of USS CONSTITUTION vs. HMS JAVA, British frigates were prohibited from engaging the American heavy frigates in single combat. Instead they were required to have a numerical advantage before they were allowed to offer combat.