Was Bellona a 64-gun ship?

Was the Bellona class a 64-gun ship type in Royal Navy service, as labelled in Ultimate Admiral: Age of Sail?

No; the Royal Navy's Bellona class consisted of 74-gun ships and represented an early form of the 74.

Ultimate Admiral: Age of Sail labels a Bellona-class vessel as a 64-gun ship. Historically, the Royal Navy's Bellona class consisted of 74-gun ships and represented an early form of the 74. That places the class in a different line-of-battle category from a true 64-gun ship. The correction concerns the historical ship type and makes no claim about the game's balance or mechanics.