Why age-of-sail crews kept working under fire

Did age-of-sail sailors take cover when incoming fire was heard?

Generally no; there was little useful cover, and leaving their stations meant surrendering the ship's ability to fight back.

Most gun crews were already working inside the ship's decks, where wooden structure offered limited protection from heavy shot. Sailors on the upper deck still had to preserve control of the ship and prevent an easy boarding. Leaving a station meant ceasing to fire, handle sails, or perform another essential task. An enemy allowed to shoot without reply gained far more than the crew gained from trying to hide.