Unlike the British Navy, the US Governement felt no need for so called Ships of the line. In 1791, the Government was strapped for cash and probably couldn't have afforded to develop a navy of such ships even if it wanted to. For this reason the US Navy ignored the conventional wisdom of the day and created a Navy consisting of six rather large Frigates.
The British consider this "bastard navy" laughable to say the least. However the US Government felt their motives were practical. They could build possibly twice as many frigates as ships and thus better patrol their coast. The frigates were also more manueverable and if working in tandem would be more than a match even if out gunned against a ship of the line. Furthermore, the loss of frigate would not be as costly as the loss of a ship.
In the end, the British would learn a valuable lesson about fighting strategy and would no longer laugh at this bastard navy.
What the Constitution lacked in size and gun power was made up for in the quality of its construction. It was nick named "Old Ironsides" after being attacked by The British Ship Guerriere. The cannon balls from the Guerriere bounced off the side of Constitutuion and a Britsh sailor exclaimed "her sides are made of Iron". In reality it was top quality white oak planking.
As Frigates go, the Constitution was a big one, 204 feet long but just 175 feet at the waterline. This reduction in size helped to make her a fast ship. Frigates typically carried twenty to forty guns arranged on one and half decks. The Constitution carried fifty guns almost filling two whole decks. The guns were also larger than those normally carried on a frigate. While a frigate would normally carry guns ranging from 12-24 pounders. The Constitution has two 24 pounder (chasers), thirty-two 24 pounders (long guns)and twenty 32 pounders (carronades) which equalled the caliber of guns carried on Ships of the line. With its acre of sail and her slim underbody, she had a remarkable top speed of 14 knots. This made her faster than any ship of the line and most frigates.
Her first mission...What else, subdue the Barbary Corsairs as well as protect merchant ships from West Indian pirates. The Constitution was never defeated in battle.
If you get the chance, you should visit the USS Constitution site and view the virtual tour. It will give you a good idea of life aboard a Frigate