Heavy frigates and the razée answer

Heavy American frigates used unusually substantial timbers to gain an advantage in a one-on-one fight against ships in their own class. Their construction was still lighter than that of a ship of the line, while a razée retained more of the larger hull's toughness after losing a gun deck. A razée could meet a heavy frigate on equal terms, but converting ships of the line into such specialists usually sacrificed an asset with broader fleet value. The Royal Navy kept only a limited number for specialized work, including operations close to the French coast. A purpose-built heavy frigate and a cut-down battle-fleet hull therefore occupied different force-structure niches.