How many destroyers can screen a capital ship?

How many destroyers are too many when escorting a capital ship?

He suggests that more than roughly nine destroyers per capital ship can become counterproductive because the screen starts to crowd the capital ship's movement.

Escort numbers involve a tactical balance rather than a simple case of more ships being better. A very dense screen can obstruct a battleship's movement and increase the risk of collisions, while a smaller screen may leave gaps in protection. The rough ceiling of nine destroyers per capital ship is therefore a handling judgement, not a universal mathematical rule. Fleet screening depends on sea room, formation control, and ship handling as well as firepower.