Anson's threshold and the 74-gun balance

Lord Anson declared in 1754 that ships with fewer than 64 guns should not stand in the line of battle. That judgement disrupted older boundaries in which fourth rates could still count as line-of-battle ships. It also gave designers a clearer floor for firepower while timber cost and hull complexity remained constraints. Continued refinement produced a two-deck ship carrying 74 guns as the practical balance. The type could deliver line-of-battle power without the extra wood and structure of a three-decker. This is the decision point where an administrative rating, an operational requirement, and an industrial limit converge.