Designing an age-of-sail ship to repel boarders

How could an age-of-sail warship be designed to repel boarders and let the crew below reach the main deck safely?

Use protected stairways opening into prepared defensive positions, supported by small guns loaded with grapeshot.

Stair-like access routes at both ends of the ship would be safer than relying only on exposed ladders. Each route would emerge behind a door into a prepared defensive position, giving men below a protected place to assemble. Small cannon loaded with grapeshot could sweep a deck already occupied by boarders. The layout turns internal circulation into a damage-control and counter-boarding system instead of leaving reinforcements vulnerable as they climb.