Thanks Dobbs that clarifies the issue very well for me. I should have remembered the lack of elevation available on guns of the period because of the inability of the carrage to take the strain. I think the Ares stats take into account the fewer number of guns but not the stronger hitting power of a fortress with its larger calibre and stable gun platforms. That factor will need consideration. I also like your idea about critical return hits from the ships being factored in. Also food for thought.
Rob.