The term "rig for silent" is a naval military expression often used in the context of submarine operations. It is an order to minimize noise levels within the submarine in order to reduce the chances of being detected by enemy sonar or other listening devices. This can involve shutting down non-essential systems, restricting movement of personnel, limiting loud activities, and taking other measures to minimize sound emanations from the vessel.

This command is critical during covert or stealth operations, where a submarine must remain undetected while it navigates through potentially hostile waters. The idea is to make the vessel as quiet as possible so that it is more difficult for enemies to locate it using acoustic detection methods.

The term is often dramatized in films and literature about naval warfare, but it is rooted in actual practices designed to enhance the stealth capabilities of a submarine.