Explosive shells make Trafalgar far more lethal

What if both fleets had explosive shells at the Battle of Trafalgar?

Casualties would rise sharply on both sides, but Britain's greater sea practice and better gunnery would still tell once the fleets reached broadside range.

The immediate answer is carnage: explosive shells would magnify the human cost far beyond solid shot. Both fleets would suffer much more severely once broadsides began to land. British ships had more opportunity to practise gunnery at sea than their French opponents. The counterfactual therefore changes the lethality of Trafalgar without erasing that Royal Navy training advantage.