Zhenyfer Ahrmahk-class

I'm trying to figure out why the Zhenyfer Ahrmahk-class was designed and built. Based on the number of guns and decks, the class is roughly equivalent to a British three-decker second-rate ship-of-the-line, but as Merlin would be well aware, for reasons of expense, maneuverability, and conservation of manpower, the Royal Navy was primarily focused during the Napoleonic Era on building two-decker third-rates, especially 74s, for its ships-of-the-line. Conversely, the larger first-rates were also three-deckers, but better sailers because they were longer. Second-rate ships basically were economy vessels, suitable for serving as flagships of colonial squadrons, but not nearly as good as either first-rates or third-rates when it came to sailing.

The only thing that makes any sense is that they were always intended to be razeed down to one-deck ironclads, but that begs the question of why any were ever built as designed. Even if one assumes they had laid down more hulls than needed as ironclad galleons in case the City-class was either delayed or disappointing, given the generally lackluster experience the Royal Navy had with second-rates, why not complete them as two-decker fourth-rates for less cost and manpower? (Razeed down to two decks, the Zhenyfer Ahrmahk-class would be either a large fourth-rate or a small third-rate in the RN rating system.

I presume RFC intended the Zhenyfer Ahrmahk-class to be equivalent to first-rates, but if so, it is undergunned. (Or perhaps the ICN overcompensated for the hogging problems suffered by the Empress of Charis and designed them like first-rates, but only gunned them like second-rates?)

I think the explanation comes down to Occam's Razor: They were built because they were the next size up in line.

Remember, Merlin wasn't in the habit of micro-managing what Charis was doing. He was providing guidance, yes, but also letting them make their own way. On what basis (especially considering when these ships were introduced) would Merlin have realistically stepped in to say "Wait, I've had a vision that says this ship design is not ideal because of x, y, and z and you should reconsider."

The ship class served a purpose, and part of that was Charis learning to think for itself. Bigger is not always better - more is not always better: As they learned about gun spacing on earlier ships. Building the ships were not going to cause serious problems for Charis - they would have some number of ships that were less than ideal for their role but still vastly superior to anything else anyone else was building. And by the time they became known as not ideal, they were obsolete (as any 3rd rate or 1st rate became) due to other advances.