Could a third British column have protected Nelson?

What realistic change might have saved Nelson at Trafalgar?

Keeping the ships detached shortly before battle could have supported a three-column attack and changed Nelson's exposure.

The playful rescue question is answered by changing the fleet rather than adding a fantasy warship. Retaining the second-rate and other vessels that left Nelson shortly before Trafalgar would give him more ships. Nelson could then attack in three columns instead of two. That formation might alter the pressure on Victory and Nelson, although the passage remains a tactical counterfactual rather than a claim of certain survival.