Second rates fit missions and yards that first rates could not

Why build second-rate ships of the line if first rates were more powerful?

First rates cost much more and required rarer building and maintenance facilities, while second rates still provided a three-decked flagship or battle-line ship where local missions and yards did not justify the largest type.

First rates were not a small incremental upgrade over second rates. They consumed substantially more material, labour, money, and dockyard capacity. A second rate could provide three decks and flagship presence in a distant station without demanding facilities sized for the largest ships. HMS Victory nearly being too broad for her dock gate illustrates how physical infrastructure constrained what could be built and maintained, even when the larger ship was tactically superior.