OAL would be my suspicion... somehow when we were researching Constitution a wire got crossed and she was scaled to 190' for main deck rather than OAL. Bad news for Old Ironsides accuracy, good news is you have a Razee USS Independence right out of the box. (Too bad she's 20 years too late for the game...)

Most of this discussion is oriented more at casual folks than Plank Counters, though... I'm actually considering replacing all of my Ares Meregildos and Nepomuceno models with Henry's because even though Purisima Concepcion has some subtle differences from Meregildos it's close enough in size and engineering that Rif Winfield referred to the taken San Josef and Salvador del Mundo as near-sisters.