Gun-deck height, stability, and seakeeping

Why did frigates acquire an empty deck below the gun deck, and how did designers balance gun height against stability?

The extra deck subdivided a deeper hull and raised the battery for rough-water use, but designers still had to keep the guns low enough to avoid dangerous topweight.

The deck below the battery was a practical subdivision of an enlarged hold that also created room for crew and stores. Raising the gun deck helped keep ports clear of North Atlantic seas, while mounting heavy guns too high could make a maneuvering ship unstable. French mathematical standardization is contrasted with a British pattern of smaller experimental classes and experience-led adaptation, especially for ships expected to remain effective far from home.