Hence why i'd test it and not just proclaim we solved the great carronade debate!
In all seriousness though, it would be rather different. Plus, how often do you really manage to make your ship stay perfectly still? Any movement will translate to damage, just not a fixed rate when you're sitting on the ground. A carronade would ram. LJ is usually accompanied with another gun (not my lumberfish) and even if not, they generally run support over kill. I think this ultimately hits the "gameplay vs realism" barrier though. The tactics sound fun at least.